SynDEx v7 User Manual

Julien Forget, Christophe Gensoul, Maxence Guesdon
Christophe Lavarenne, Christophe Macabiau,
Yves Sorel, Cécile Stentzel

Contents

Introduction

This manual uses some writing conventions:

Chapter 1  Overview

1.1  The AAA methodology

SynDEx is based on the AAA methodology (cf. chapter 12).

A SynDEx application is made of:

Performing an adequation means to execute heuristics, seeking for an optimized implementation of a given algorithm onto a given architecture.
An implementation consists in:

1.2  SynDEx distributions

SynDEx runs under Linux, Windows, and Mac OS X platforms. SynDEx is written in Objective Caml. The Graphical User Interface is written in Tcl/Tk with the OCaml library CamlTk. See chapter 12 for web links.

Chapter 2  Getting started

2.1  Application workspace

2.1.1  Launching SynDEx 

SynDEx is launched by running the SynDEx executable, located in the directory bin of your installation directory. Some options can be specified on the command line, for example :

The complete list of options can be obtained by running the SynDEx executable with the --help option.
For example write the command line:
> /syndex-7.0.x/bin/syndex-7.0.x -libs /syndex-7.0.x/libs -html /usr/bin/firefox appli.sdx
In this example the libraries directory and the web browser used to display the manuals are specified on the command line. In addition, the name of an application to open is also specified, otherwise only the principal window is opened.

2.1.2  SynDEx principal window

Figure 2.1: SynDEx principal window

To create an application workspace, run the SynDEx executable without the name of an application. It opens the principal window of SynDEx (cf. figure 2.1).

2.1.3  Load a SynDEx application

Figure 2.2: Open a file

To load an existing application in the workspace, from the File menu, choose the Open option and select a SynDEx file (cf. figure 2.2). For example load the /syndex-7.0.x/examples/basic/basic.sdx example.

2.1.4  Algorithm and architecture windows

Figure 2.3: Algorithm window in examples/basic/basic.sdx
Figure 2.4: Main architecture window in examples/basic/basic.sdx

Loading a SynDEx application will open:

Opening another application will replace the current one by the new one in the workspace.
Warning: some application may require libraries (cf. Chapter 3).

2.2  Modes

In the algorithm window, the adress bar displays AlgorithmMain (main) meaning that the main algorithm is viewed in the main mode (cf. section 5.1.2). Double left click on AlgorithmMain in the Definition list. The algorithm is now viewed in its definition mode and the adress bar displays [Function] AlgorithmMain. See section 5.1.2 for more information.

Note that you can create several algorithms and architectures but only one main algorithm and one main architecture on which the adequation will be applied.

2.3  Adequation and code generation

To launch the adequation of the main algorithm (cf. Main mode in section 5.1.2) onto the main architecture (cf. section 6.3.2), from the Adequation menu of the principal window, choose the Launch Adequation option. To save the result of the adequation, from the Options menu, check Save Adequation with Application. Then save your application. To view the computed schedule, from the Adequation menu, choose the Display Schedule option. See chapter 9 for more information.

To generate the code of the application, from the Code menu, choose the Generate Executive(s) option. The generated .m4 files are saved in the example’s directory. To view theses files from the SynDEx workspace, from the Code menu, choose the Display Executive(s) option. See chapter 10 for more information.

2.4  Save, Close, Quit

To save the current application, from the File menu, choose the Save option. To save it with a new name, choose the Save as option and type the new name in the dialog window. The file will be suffixed by .sdx.

To close the current application, from the File menu, choose the Close option. It closes all the application windows and leaves the workspace empty.

To quit SynDEx from the File menu, choose the Quit option.

Chapter 3  Libraries

3.1  To use libraries

To create a new application you may want to use pre-defined algorithm or architecture definitions contained in libraries. These definitions are called global definitions (vs. local definitions from the current application).
From the File menu of the principal window, choose the Specify Library Directories option. Then left click on the Add button of the dialog window and select the target directory. For example, specify the SynDEx libs directory and the examples/basic_with_library/basicLibraries directory.
To include a library in an application in order to make references to the objects it contains, from the File menu of the principal window, choose the Included Libraries option. Then check the target library. Uncheck an already included library to un-include it, provided there are no references in your application on definitions from this library.

3.2  To create a library

To create a library of algorithm or architecture definitions, you must create a .sdx file containing the definitions you need. Libraries may be located in the libs directory, at the root of your installation directory. Or you will have to specify their location to the SynDEx application (cf. section 3.1).

Chapter 4  Using the interface

4.1  Selection

Selection may be applied to vertices or edges of both algorithm or architecture graphs.
Left click on a vertex (resp. an edge). Red squares appear on its borders, meaning that the vertex (resp. the edge) is selected. To select multiple vertices and/or edges, use the shift key. To select a set of vertices and/or edges, use the left button of the mouse while dragging it, in order to draw a square when the button is released. Vertices inside or intersecting the square are selected.
To move a selection, left click on a vertex of the selection. Then drag it until the target position and release the mouse. To cancel a selection left click outside the selection.
Contextuals menus are available on selections (cf. section 4.3).

4.2  Zoom

Zoom may be applied to architecture (cf. chapter 6) and schedule windows (cf. section 9.6) by moving the zoom cursor on the border of these windows.

4.3  Contextual menus

Some contextual menus are available in SynDEx. Contextual menus mainly include edition commands (Copy, Cut, Paste, Delete).

Algorithm window

In the algorithm window, right click on the background of an algorithm definition window. It opens a contextual menu on the target definition. Left click on a vertex (function, delay, sensor, actuator, constant) of an algorithm graph. Red squares appear. Then right click the mouse. It opens a contextual menu on the target reference.

The Activate Info Bubbles option displays additionnal information when pointing the cursor at a vertex of any algorithm graph.

Architecture window

In an architecture window, right click on the background or left click on the Edit menu. It opens a contextual menu on the target definition. Left click on a vertex (operator, communication medium) of an architecture graph. Red squares appear. Then right click the mouse. It opens a contextual menu on the target reference.

4.4  Contextual information

When the cursor points at an object of an algorithm (cf. chapter 5), an architecture (cf. chapter 6) or a schedule window (cf. section 9.6), information is displayed in the principal window.
By default information is not kept when switching between objects. The new information overwrites the older one. To change this behaviour and keep all the information, from the Options menu of the principal window, check Keep Information in the Principal Window. This is for instance useful when the information displayed does not fit in the window, which requires to scroll the principal window.

4.5  To find an object

Looking for a vertex, from which you now the name, in a complex graph can become rather tedious.

Architecture window

In the architecture window (cf. chapter 6), from the Edit menu, choose the Find Operator Reference or Find Medium Reference option to locate a vertex of your graph by its name. It opens a window listing all the vertices of your graph. Double left clicking on one of them will select it.

Schedule window

In the schedule window (cf. section 9.6), from the Edit menu, choose the Find Operation option to locate an operation of your graph by its name. It opens a window listing all the operations of your graph. Double left clicking on one of them will select it.

4.6  Refresh

To refresh an architecture window, from its Window menu, choose the Refresh option. If necessary, re-open the algorithm window (cf. Algorithm window in chapter 5) to refresh it.

Chapter 5  Algorithm

AAA methodology

In the AAA methodology, an algorithm is specified as a directed acyclic graph (DAG) infinitely repeated. Directed means that for each edge representing a relation between vertices, the vertices tuple is ordered, i.e. its first element is the source vertex and the other one(s) is(are) the destination vertex(vertices). A vertex is an operation corresponding to a sequence of instructions which starts after all its input data are available and produces all its output data at the end of the sequence. An edge is a dependence between two vertices corresponding to a data transfer and an execution precedence, or to an execution precedence only. Note that some vertices may be independent, i.e. may not be connected by dependences.

Definition vs. reference

In SynDEx there is a distinction between algorithm definition and algorithm reference. A definition preexists to a reference that corresponds to one an only one definition. On the contrary, to a given definition may correspond several references. That allows for referencing, with different names, a unique definition. Therefore, an algorithm is described by a definition, which is a DAG similar to those in AAA, where vertices are references or ports, and edges are dependences between references, or between references and ports.

Atomic or hierarchical definitions

To a given reference contained in a definition corresponds a definition which may contain itself several references, and so on. That corresponds to hierarchy. A definition is said hierarchical when it defines an algorithm which contains at least one dependence connecting an input port to an output port, and possibly one or several references connected by dependences, otherwise it is said atomic.

There are five types of atomic definitions: functions read data on input ports, execute instructions without any side-effect, write data on output ports, sensors are input vertices of the DAG producing data from a physical sensor, actuators are output vertices of the DAG consuming data for a physical actuator, constants are input vertices of the DAG, with null execution time, delays memorize data during one or several infinite repetition of the DAG, for use in next repetitions. These types are detailed in section 5.1.1.

A definition is said explicitly hierarchical when the algorithm contains at least one dependence (and possibly references). This includes conditioning (cf. section 5.2), repetitions (cf. section 5.3) of hierarchical definitions, and more generally definitions defined through several levels of hierarchy. Only a function may be defined through explicit hierarchy.

A definition is said implicitly hierarchical when the algorithm does not contain any dependence and yet will be transformed by SynDEx, for the adequation, into a graph which contains dependences. This happens only with repetitions (cf. section 5.3) of atomic definitions.
Warning: A hierarchical definition does not have to wait for all its input data to be available before starting some computations. Indeed, parts of the algorithm graph of a hierarchical algorithm definition may only require parts of the input data of the definition and therefore can start as soon as this part is available (and not all the data). In the same way, some data may be produced before the end of the complete sequence of computations.

Dependences

There are two types of dependences:

A data dependence imposes that the reference at the source of the dependence, produces data and is executed before the reference at the destination of the dependence, which consumes the data. A precedence dependence only imposes an execution order between references, no data is produced or consumed.

Algorithm window

Definitions and references are managed through analgorithm window. If necessary it is possible to open several algorithm windows.

Figure 5.1: Algorithm / New Algorithm Window
Figure 5.2: Algorithm Window

From the Algorithm menu, choose the New Algorithm Window option (cf. figure 5.1). It opens an algorithm window for algorithm definitions (cf. figure 5.2). Left click on the background of a definition window: the algorithm window shows its Definition Properties. Left click on a reference in this definition window: the algorithm window shows its Reference Properties. These definition or reference properties appear in the left bottom part of the algorithm window (cf. figure 5.4 for definition properties and figure 5.5 for reference properties).

5.1  To create an algorithm definition

5.1.1  To create a definition

Types of definitions

SynDEx distinguishes five types of definitions with different edition rules:

New definition

Figure 5.3: Definition of a sensor

To create a new definition, in the algorithm window, left click on the + green button. It opens a dialog window in which you can select the definition’s type. For example check Sensor (cf. figure 5.3). Type the name of the new sensor and optionally parameters. For example type input. Then left click OK. It creates a definition of sensor named input.

Definition with parameters

Parameters are local to the scope of a definition. Often, parameters are used to create more generic definitions. For example, the increment of an incrementer can be given as a parameter of the incrementer definition. Parameters of a definition are names (not values) separated by semi-colon between < and > following the name of the definition, according to the following syntax:

  parameters ::= "<" { parameter ";" } parameter ">"
  parameter ::= name

where curly brackets {...} represent zero, one or several repetitions of the enclosed element, and keywords are quoted.

You can also edit the parameters of a definition directly in its Definition Properties (cf. figure 5.8) using the same syntax. The parameters will be instanciated (values given to names) when the definition will be referenced (cf. section 5.1.4). The only definition whose parameters can be instanciated, is the main algorithm (cf. section 5.1.2) only through its field Values in its Definition Properties (cf. figure 5.8).

5.1.2  Definition mode and main mode

This section refers to section 2.2.

Definition mode

Figure 5.4: C definition in examples/hierarchy/hierarchy.sdx
Figure 5.5: Opening B1 reference in examples/hierarchy/hierarchy.sdx
Figure 5.6: B definition in examples/hierarchy/hierarchy.sdx

Double left click on a definition name in the Definition list (e.g. open the examples/hierarchy/hierarchy.sdx application and double left click on C in the Definition list). You are now in a definition mode (cf. figure 5.4). From a definition mode, to open the definition corresponding to a reference in order to inspect and possibly modify its content, left click on the target reference to select it. Red squares appear on its borders (cf. figure 5.5). Then double left click on it. It displays the definition of the target reference (cf. figure 5.6).

Note that as soon as you have included an algorithm library (cf. section 3.1), all its definitions appear in the definition list. The Definition list in figure 5.4 shows some local definitions (e.g. A, B, C, Main) and global definitions (e.g. int/Arit_add, int/Arit_div, etc.) since the integer library was included.

Main mode

Figure 5.7: Set Main definition as main algorithm in examples/hierarchy/hierarchy.sdx
Figure 5.8: Main mode in examples/hierarchy/hierarchy.sdx

To define an algorithm as main, right click on the background of the target definition window. Choose the Set As Main Definition option (cf. figure 5.7). The color of the background changes and the adress is changed from a [Function] to a (main), meaning that you are now in the main mode on the main algorithm (cf. figure 5.8). Note that the main algorithm must be at the root level of a hierarchy; it can not contain unconnected ports. Only the main algorithm can instanciate (give values to names) its parameters (cf. section 5.1.1) thanks to its field Values in its Definition Properties (cf. figure 5.8).
Left click on the Main button of the algorithm window. It displays the main algorithm in the main mode. Left click on a hierarchical reference to browse down the main algorithm (e.g. left click on the C reference of Main then left click on the B2 reference of C). Then left click on Up In Main to browse up the main algorithm.

Hierarchy

Now you may construct a graph with references to constants, sensors, actuators, delays and functions. If this definition is intended to be referenced in an explicit hierarchy, i.e. this reference will belong to a certain level of hierarchy (possibly a leaf), you must use input and output ports. If this definition is intended to be referenced at the root level of the hierarchy, input ports are replaced by sensors and output ports are replaced by actuators.
References to an explicitly hierarchical definition are displayed with a double-border (in the figure 5.4 B1 is a reference on an explicitly hierarchical definition contrary to add).

5.1.3  To create a port in a definition

Ports are communication interface of a definition with the outside world.

Direction of ports

SynDEx distinguishes three directions for ports:

New port

Figure 5.9: Contextual menu → Create port
Figure 5.10: Name of the new port
Figure 5.11: A definition after port creation

To create a port in an atomic definition (cf. chapter 5):

You can undo and redo this action, right click on the background and choose the Undo, Redo options.

A port definition has the following syntax:

  port_definition ::= direction type [ "[" size "]" ] name
  direction ::= "?" | "!" | "&"

where:

square brackets [...] represent optional elements, pipes ∣ represent alternatives, and keywords are quoted.
Hint: you can create several ports in one breath by simply putting several port definitions in a row in the dialog window, according to the following syntax:

  port_definition ::= { port_definition }

where curly brackets {...} represent zero, one or several repetitions of the enclosed element.

Ports order

If you plan to generate code, it is necessary to specify an order for ports which is consistent with the declaration of the corresponding executable function. To specify the ports order, right click on the background and choose the Ports Order option.

Input/output ports

Input-output ports have a very specific behavior concerning data memory allocation in the executives generated by SynDEx. For any application, SynDEx makes data buffer allocations for (and only for) the output ports of the atomic references of your algorithm graph. Input-output ports do not cause an allocation but instead an alias on the output port of its predecessor. The operation containing this input-output port directly modifies the value of its predecessor port (side-effect). This is useful to avoid reallocation of big data buffers of the same type (for instances images) by making successive computations on the same data buffer.
However, as side-effects are not supposed to happen in data-flow graphs, this comes with some restrictions:

5.1.4  To create a reference in a definition

A reference can be thought as a call to a function in a traditional programming language. Here the called function is an algorithm definition.

New reference

Figure 5.12: A reference to myReferencedDef into myDefinition

To reference a definition (e.g. myReferencedDef) into another one (e.g. myDefinition), set the algorithm window in definition mode on myDefinition (cf. section 5.1.2). Then drag and drop myReferencedDef from the Definition list to the definition window (or select myReferencedDef in the Definition list, right click on the background of the definition window, and choose the Create reference option). It opens a dialog window. Type the name of the reference (e.g. myReference). See figure 5.12 to see the result.

Reference with parameters

To reference a definition with parameters (cf. section 5.1.1), a valued expression is required for each parameter of the definition. Parameters of a reference are valued expressions separated by semi-colon between < and > following the name of the reference, according to the syntax:

  expr_list ::= "<" { expr ";" } expr ">"
  expr ::= name | value | "(" expr ")" | expr "+" expr |
           expr "-" expr | expr "*" expr | expr "/" expr |
            "-" expr | "{" { expr "," } expr "}"
  valued_expression ::= expr

where curly brackets {...} represent zero, one or several repetitions of the enclosed element, pipes ∣ represent alternatives, and keywords are quoted. A parameter is instanciated when it has a value otherwise it is not.

You can also edit the parameters in the Reference Properties with the same syntax. Note that the number of valued expressions must match the number of parameters of the referenced definition, and that types must match.

5.1.5  To create a dependence in a definition

A dependence is a directed edge connecting a producer operation to one or several consumer operations. As such, it specifies an execution order relation between two references used in a definition.

SynDEx distinguishes two types of dependences: data dependences and precedence dependences (without data) (cf. introduction of chapter 5). SynDEx automatically creates the right type of dependence depending on the context:

5.1.6  To create a superblock

A superblock is a set of operations, edges and ports extracted as a new definition.

To create a definition as a superblock, select the target set of operations, edges and ports you want to extract (cf. section 4.1). Then right click and choose the Extract as superblock option. A new definition is created and a reference to this definition replaces the selected set. The new definition is available in the Definition list, You can rename both the definition and the reference.

You can undo and redo this action.

5.1.7  To create an abstract reference

An abstract reference is a reference to a hierarchical definition in which the hierarchy is not taken into account, i.e. the flattening (cf. section 9.5) does not go into the hierarchical referenced definition that becomes therefore abstract. However, note that to perform the adequation this definition must have a duration.

To create an abstract reference, select the desired hierarchical reference then, check the option Abstract in the Reference properties of this reference.

You can undo and redo this action.

5.2  To condition an algorithm definition

First make sure that the target definition contains an input port of type int for the conditioning port. Note that the SynDEx libs directory already provides an int library for operations on integer values.

New condition

Figure 5.13: switch definition mode for cond = 3 in examples/condition/simpleCondition/simpleCondition.sdx

Right click on the background of the definition window and choose the Create Condition option. It opens a dialog window for the new condition. A condition is a port = value expression where port is the name of the conditioning port and value is an integer. Note that the conditioning port must be of direction input (cf. 5.1.3). A new tab is created for the given condition. The conditioning port is now colored in yellow (cf. figure 5.13).

If necessary, refresh the algorithm window (cf. section 4.6).

Remarks

Note that there can be only one conditioning input port. You have to construct one sub-graph per value associated to a conditioning input port (cf. figure 5.13). For each other value of the conditioning input port, the result is unspecified and will be inconsistent.

CondI and CondO vertices

The adequation and the code generation will take into account the expanded graph (cf. section 9.5). SynDEx will introduce new vertices during the expansion: CondI and CondO vertices.

A CondI vertex consumes the conditioning data and connects the input ports of the conditioned operation according to its value.

A CondO vertex consumes the conditioning data and connects the output ports of the conditioned operation according to its value.

References

Figure 5.14: conditioned definition mode in examples/condition/simpleCondition/simpleCondition.sdx

In a definition mode (cf. section 5.1.2), references to conditioned definitions have their conditioning port yellow colored (cf. figure 5.14).

Delete a condition

Right click on the background of the definition window and choose the Delete Condition option.

5.3  To repeat an algorithm definition

5.3.1  Diffuse, Fork, and Join

You can create a reference to a definition, and connect to its input (resp. output) ports some output (resp. input) ports with different sizes. The pre-condition is to have a unique common multiple between each pair of ports of different sizes. This multiple is the repetition factor of the reference.

Multiplication of a vector by a scalar

Figure 5.15: AlgorithmMain1 definition mode in examples/tutorial/example4/example4.sdx

Suppose that you want to specify the multiplication of a vector by a scalar giving a vector as result (cf. AlgorithmMain1 in examples/tutorial/example4). You can specify it by repeating the multiplication between two scalars instead of defining a new one. For example for N length vectors, you may specify the repetition by N multiplications between scalars giving a scalar as a result (cf. figure 5.15).
You have to:

Repetition factor

The common multiple between each pair of ports with different sizes is N. It is the repetition factor that you have to set explicitely by using a symbolic numbered expression.

Diffuse the scalar

Since the output port of s_input has the same size as its connected input port of the multiplication function, it is replicated N times in order to be multiplicated by each element of v_input. This is a Diffuse operation.

Fork the vector

Since the function operates on scalars and the v_input vector has N elements, each of its elements are provided separately in order to be multiplicated. This is a Fork operation.

Join the internal results

Since the function operates on scalars and the v_output vector has N elements, each repetition of the multiplication is taken in order to be provided as a N elements vector. This is a Join operation.

Representation

Figure 5.16: matprodvec main mode from AlgorithmMain3 main algorithm in examples/tutorial/example4/example4.sdx

The repetition factor is displayed next to the name of the reference (e.g. in the figure 5.15 mul is repeated N times). The main algorithm (e.g. AlgorithmMain3) instanciates its parameters (cf. figure 5.8). From the main mode in examples/tutorial/example4/example4.sdx (cf. section 5.1.2), double left click on the matprodvec reference, the dotprod reference is repeated three times (cf. figure 5.16).

Explode and Implode vertices

The adequation and the code generation will take into account the expanded graph (cf. section 9.5). SynDEx will introduce new vertices during the expansion: Explode and Implode vertices.

An Explode vertex extracts for each repetition of a definition each element of the data it receives (cf. subsections Diffuse and Fork).

An Implode vertex builds the data it sends by concatenating each separated element produced by each repetition of the definition (cf. subsection Join).

5.3.2  Iterate

In some cases, you may want to repeat a reference but have no difference between port sizes.

Multiplication of two vectors

Figure 5.17: dp definition mode in examples/tutorial/example4/example4.sdx

Suppose that you want to specify the multiplication of two vectors giving a scalar as a result (cf. figure 5.17). You can specify it by repeating the multiplication between two scalars, that used an accumulator to store the partial sum. For example if for dpaccn length vectors, you may specify the repetition by dpaccn multiplications between three scalars (the i element of the first vector, the i element of the second one, and the accumulator, initialized to 0).

You have to:

The accumulator is initialized with {0}. Then the output of the repetition i becomes the accumulator of the repetition i+1. The output of the last repetition is the output of the repeated definition. This is an Iterate operation.

5.4  To modify an algorithm definition or a reference

5.4.1  Modify a definition

Double left click on the definition name in the Definition List or double left click on a reference from a definition mode (cf. section 5.1.2). It opens its definition window. Right click on the background of the definition window. Choose the Create dependence option (cf. section 5.1.5), Create port (cf. section 5.1.3), Create reference (cf. section 5.1.4), Create Condition or Delete Condition (cf. section 5.2) to modify the definition.

As soon as you have Left clicked on the background of a definition window (cf. Algorithm window in chapter 5) you can change its Definition Properties to modify its Name, Description, Parameters or Values. The latter property appears only in the case of a main algorithm definition.

Note that you can modify local and global definitions (cf. section 3.1). Modifications on a global definition impact only the current application and the library remains unchanged. To modify a global definition over-all, open the corresponding SynDEx library file (e.g. libs/int.sdx). Modifications on a definition in a library may have consequences on all the applications using this library.

5.4.2  Modify a reference

Left click on a reference in a definition window (cf. Algorithm window in chapter 5). Use its Reference Properties to modify its Name, Parameters, Repeat or Period. For the period see the section 5.7 “To build mutli-periodic applications”.

5.5  To delete an algorithm definition

To delete a definition, in the algorithm window, left click on the - red button.

Note that deleting a global definition (cf. section 3.1) impacts only the current application.

5.6  To associate code with an algorithm definition

5.6.1  The code editor window

Figure 5.18: Edition of the conv code phases in examples/tutorial/example7/example7.sdx
Figure 5.19: Edition of the code associated with conv in examples/tutorial/example7/example7.sdx
Figure 5.20: Code associated with conv in loop phase in examples/tutorial/example7/example7.sdx

Right click on the background of a definition window. Choose the Edit code phases option (cf. figure 5.18). Check init (resp. end) to generate code in the initialization phase (resp. ending phase).

Right click on the background of a definition window. Choose the Edition of the associated source code option (cf. figure 5.19). It opens the code editor window on the initialization phase for the selected definition. Left click on loop phase (resp. end phase) to edit the code associated in the loop phase (resp. ending phase) (cf. figure 5.20).

5.6.2  The code editor macro language

Figure 5.21: M4 macro code for conv in examples/tutorial/example7/example7_sdc.sdx

From the Code menu of the principal window, check Generate m4x files. At code generation time, the code written in the code editor will be wrapped into M4 macro code, and outputed into an application_name_sdc.m4x file. These files contain one M4 macro definition per algorithm definition (cf. figure 5.21). The code editor offers several macros to abstract away the M4 nature of the output file. These macros are of two kinds: port and parameter names translation macros, and quoting macros (cf. macros directory).

Names translation macros

Parameter and port names of an algorithm definition are encoded as parameters of the corresponding M4 macro. Because the M4 language uses positional parameters, when you want to refer to a parameter or port in the associated code he has to know its position in the M4 macro parameters list. More than being not very handy, this is fragile relatively to creation or deletion of ports and parameters in the definition: when you create a port or a parameter to a definition, he has to adjust (replace $n by $n+1 in) all references to parameters or ports coming after the created one in the parameters list of the M4 macro. To overcome this difficulty, the code editor recognizes the following macros (cf. figure 5.20):

Quoting macros

Quoting macros are used to wrap or unwrap code by M4 quote. The code editor recognizes the following quoting macros:

5.6.3  The code editor shortcuts

The code editor supports various keyboard shortcuts that could be handy when editing source code.

Ctr-TabInsert a tabulation.
TabComplete a port name. Type the beginning of a port name, then press Tab
 and as many times as necessary for the editor to find the wanted completion.
Ctr-IInsert the @IN macro at cursor position.
Ctr-OInsert the @OUT macro at cursor position.
Ctr-NInsert the @INOUT macro at cursor position.
Ctr-PInsert the @PARAM macro at cursor position.
Ctr-TInsert the @TEXT macro at cursor position.
Ctr-QInsert the @QUOTE macro at cursor position.
Ctr-WCut the selected text into the clipboard.
Ctr-KCut text from cursor position to the end of the line.
Alt-WCopy the selected text into the clipboard.
Ctr-YPaste the clipboard content at cursor position.
Ctr-AJump to the beginning of the line.
Ctr-EJump to the end of the line.
Ctr-upJump to the beginning of the buffer.
Ctr-downJump to the end of the buffer.

5.7  To build multi-periodic applications

Until version 6 of SynDEx a unique timing information (execution duration) is associated to each operation (resp. each data type of a dependence) relatively to the operators (resp. media) it may be distributed onto. This timing information, which depends on the hardware, is associated to the definition of every operation. Applications specified by the user with version 6 are implicitely mono-periodic, meaning that all the operations of the algorithm graph have the same period which is equal to the total execution time of all the operations executed on the different components of the architecture, taking into account the duration of data communications through the media. This total execution time is displayed as the value of the “Cycle time” in the schedule window resulting from the adequation.

Version 7 of SynDEx allows the user to specify, in addition to a duration, a period to each operation. The period is a timing information associated to the reference of an operation instead of its definition, which does not depend on the hardware. This feature allows the user to specify an operation definition with the same execution duration each time it is referenced, whereas this operation may be referenced with several periods. Note that for a given operation it is necessary that its execution duration is smaller than its period to be schedulable.

As soon as a period is associated to an operation reference, the application becomes multi-periodic, and a period must be associated to every operation reference. If it is not the case the application remains mono-periodic. For both mono-periodic and multi-periodic applications, execution durations must be associated to operation definitions and data type of dependences. A multi-periodic application has a hyper period equal to the LCM (Least Common Multiple) of all the periods associated to the operation references. This hyper period is displayed as the value of the “Cycle time” in the schedule window resulting from the adequation. Note that the “Cycle time” is different from the total execution time of all the operations executed on the different components of the architecture, taking into account the duration of data communications through the media.

Version 7 of SynDEx, using the period and the execution duration of every operation, performs a distributed real-time schedulability analysis. If the application is schedulable, SynDEx may generate the corresponding macro-code (or may not find any schedule).

Version 7 of SynDEx, using the period and the execution duration of every operation, performs a distributed real-time schedulability analysis to determine if the multi-periodic application is schedulable. If it is the case it will generate the corresponding macro-code.

Multiple or equal periods

Operations related by a dependence must have multiple or equal periods. While creating a dependence between operations which have inconsistent periods, an error message appears to help the user (e.g. Can not create dependence input.o -> compute.in in definition basicAlgorithm Error #1 [Inconsistent periods]).

While creating a dependence between operations which have multiple periods, there are two cases:

Hierarchical references

Verifications on periods are propagated to hierarchical references.

While setting the period to a hierarchical reference, SynDEx verifies that the new period is compatible with the periods of the references it contains. Actually, the period of a hierarchical reference must be equal (or multiple) to the Least Common Multiple (LCM) to the periods of the references it contains.

While setting the period to a reference contained in a hierarchical reference, SynDEx verifies that the new period is compatible with the period of the hierarchical reference. Actually, the period of a reference contained in a hierarchical reference must be equal (or must be a divisor) to the period of the hierarchical reference.

Edit the period of an operation

The user can edit the period of an operation only in its reference properties (cf. paragraph “Algorithm window” in section 5) unlike its name, its parameters and its repeat factor which can also be edited during the reference creation.

By default the period of an operation is equal to 0. Note that, as soon as an operation has a period equal to 0, the application is mono-periodic whatever the other periods are. In other words, to obtain a multi-periodic application the period of all the references must be edited.

Adequation

See the section 9.4 for details about the adequation process in case of mutli-periodic applications.

Chapter 6  Architecture

An architecture is specified as a non directed graph where vertices are of two types: operator or communication medium, and each edge is a connection between an operator and a communication medium.

6.1  Operator

6.1.1  To create an operator definition

Figure 6.1: Definition of an operator
Figure 6.2: New U operator definition window

From the Architecture menu of the principal window, choose the Define Operator option (cf. figure 6.1). It opens a dialog window. Type the name of the new operator (e.g. U). Then left click OK. It opens the new operator definition window (cf. figure 6.2). By default the code will be generated only for the loop phase of the operator. See the section 6.1.2 to set its gates, durations and code phases.

6.1.2  To modify an operator definition

From the Architecture menu of the principal window, Choose the Edit Operator Definition option. It opens a browse window. Select the target operator. It opens its definition window with Modify gates, Modify durations, and Modify code generation phases buttons.

Gates

Left click on the Modify gates button. It opens a dialog window in which you can set the gates, one per line. For example type

TCP x
TCP y

A gate has the following syntax:

 gate_definition ::= medium_definition_name gate_name

where:

Durations

Left click on the Modify durations button to specify durations by operation (cf. chapter 7).

Code generation phases

Left click on the Modify code generation phases button. Check init (resp. end) to generate code in the initialization phase (resp. ending phase).

Note that you can modify local and global operators (cf. section 3.1). Modifications on a global operator impact only the current application and the library remains unchanged. To modify a global operator over-all, open the corresponding SynDEx library file (e.g. libs/u.sdx to modify u/U). Modifications on a definition in a library may have consequences on all the applications using this library.

6.1.3  To delete an operator definition

From the Architecture menu of the principal window, choose the Delete Operator option. It lists the local operator definitions (cf. section 3.1). Select the target operator.

Note that deleting a global operator (cf. section 3.1) impacts only the current application.

6.2  Communication medium

6.2.1  To create a medium definition

From the Architecture menu of the principal window, choose the Define Medium option. It opens a dialog window. Type the name of the new communication medium. Then left click OK. It opens the new communication medium definition window. By default a new communication medium has type SAM point-to-point. See the section 6.2.2 to set its type and durations.

6.2.2  To modify a medium definition

From the Architecture menu of the principal window, Choose the Edit Medium Definition option. It opens a browse window. Select the target communication medium. It opens its definition window with Modify type, and Modify durations buttons.

Type

Left click on the Modify type button. It opens a dialog window in which you can change the type of the communication medium. For example, check SAM MultiPoint (resp. RAM).

Durations

Left click on the Modify durations button to specify durations by data type (cf. chapter 7).

Note that you can modify local and global media (cf. section 3.1). Modifications on a global communication medium impact only the current application and the library remains unchanged. To modify a global communication medium over-all, open the corresponding SynDEx library file (e.g. libs/u.sdx to modify u/TCP). Modifications on a definition in a library may have consequences on all the applications using this library.

6.2.3  To delete a medium definition

From the Architecture menu of the principal window, choose the Delete Medium option. It lists the local communication medium definitions (cf. section 3.1). Select the target communication medium.

Note that deleting a global communication medium (cf. section 3.1) impacts only the current application.

6.3  Architecture

6.3.1  To create an architecture definition

From the Architecture menu of the principal window, choose the Define Architecture option. It opens a dialog window. Type the name of the new architecture. Then left click OK. It opens the new architecture definition window. Now you may construct a graph with references to operators and media. Note that, as soon as you have more than one operator, a connection must be created between each operator and at least another operator through at least one medium.

New operator reference

To reference an operator into an architecture, from the Edit menu of the architecture window choose the Reference Operator option. It opens a browse window. Select the target operator. It opens a dialog window. Type the name of the reference. Then left click OK.

New medium reference

To reference a communication medium into an architecture, from the Edit menu of the architecture window choose the Reference Medium option. It opens a browse window. Select the target operator. It opens a dialog window. Type the name of the reference. Then left click OK. In case of a SAM multipoint medium, it opens a dialog window. Check Broadcast or No Broadcast for the mode of the reference. Then left click OK.

Note that for a SAM multipoint medium in Broadcast mode, all operators connected to this communication medium will receive every message sent on the communication medium. In case of SAM multipoint medium in No Broadcast mode, each message will be received by only one operator: the destination operator of the message. Right click on a medium reference and choose Broadcast Mode to change it.

New connection

To connect an operator and a communication medium, point the cursor at a gate of the operator reference, middle click (or Ctrl left click), then drag and drop on the communication medium reference.

Operator and medium reference deletion

To delete a reference to an operator definition or a reference to a medium definition, left click on the target operator or medium, right click, then choose the Delete option.

6.3.2  To set the main architecture

Figure 6.3: Set u/biProc as main architecture in examples/tutorial/example7/example7.sdx

Set the main operator

To define an operator of an architecture as main, left click on the target operator, right click, then choose the Set As Main Operator option.

Set the main architecture

To define an architecture as main, right click on the background of the target architecture. Choose the Set As Main Architecture option (cf. figure 6.3). The architecture window is now labelled with (main).

Edit the main architecture

To open the main architecture, from the Architecture menu of the principal window, choose the Edit Main Architecture option.

6.3.3  To modify an architecture definition

From the Architecture menu of the principal window, Choose the Edit Architecture Definition option. It opens a browse window. Select the target architecture. It opens its definition window.

Note that you can modify local and global architectures (cf. section 3.1). Modifications on a global architecture impact only the current application and the library remains unchanged. To modify a global architecture over-all, open the corresponding SynDEx library file (e.g. libs/u.sdx to modify u/biProc). Modifications on a definition in a library may have consequences on all the applications using this library.

6.3.4  To delete an architecture definition

From the Architecture menu of the principal window, choose the Delete Architecture option. It lists the local architecture definitions (cf. section 3.1). Select the target architecture.

Note that deleting a global architecture (cf. section 3.1) impacts only the current application.

Chapter 7  Characteristics

The heuristics performed by the adequation use the characteristics of each operation and each data dependence relatively to the operators and media it may be distributed onto. Presently we are mainly interested in real-time performances. Therefore the operations of algorithm graphs must be characterized in terms of duration relatively to the operators and media of architecture graphs.

7.1  Execution durations

7.1.1  Operation durations

In the algorithm window, right click on the background of an algorithm definition window. Choose the Durations option. It opens a dialog window in which you can set the execution durations of the operation by operator (e.g. u/U = 3 specifies the duration required to execute the target operation on an u/U operator).
An operation duration has the following syntax:

 operation_duration ::= operator_definition_name "=" value

where:

7.1.2  Operator durations

In an operator definition window, left click on the Modify durations button. It opens a dialog window in which you can set the execution durations on the operator by operation (e.g. bool/AND = 2 specifies the duration required to execute a bool/AND operation on the target operator).
An operator duration has the following syntax:

 operator_duration ::= operation_definition_name "=" value

where:

7.2  Communication durations

In a medium definition window, left click on the Modify durations button. It opens a dialog window in which you can set the communication durations on the communication medium by data type (e.g. u/bool = 1 specifies the duration required to transfer one element of type u/bool on the target communication medium).
A medium duration has the following syntax:

 medium_duration ::= data_type "=" value

where:

7.3  Libraries

Figure 7.1: u/U durations window in examples/basic_with_library/basicBiProc/basicBiProc.sdx

In case of a duration already specified in a library, a lib/operator_definition_name = value or
lib/operation_definition_name = value or lib/data_type = value line will appear in the corresponding duration windows (cf. figure 7.1).
You can modify durations of local and global definitions. Modifications on a duration of a global definition impact only the current application and will not be saved with the current application.

Chapter 8  Constraints

Some operations of the main algorithm graph may be constrained to be executed on specific operators of the architecture graphs. In this case the heuristics will not have the choice in distributing them. These constraints are specified through operation groups. All the operations of an operation group will be distributed onto the same operator.

8.1  To create an operation group

To create a new operation group, from the Algorithm menu of the principal window, choose the Define Operation Group option. It opens a dialog window. Type the name of the new operation group. Then left click OK.

8.2  To attach references to operation groups

Figure 8.1: algo as main algorithm in examples/tutorial/example7/example7.sdx

From the main mode of the algorithm window (cf. section 5.1.2) left click on the target reference. In its Reference Properties (cf. Algorithm window in chapter 5) left click on the Group button and select the target operation group (cf. figure 8.1).

If it references a hierarchical definition, all the references of this hierarchy will be attached to this operation group (except references of this hierarchy that may be explicitly attached to another operation group).

In particular, in case of a reference to a conditioned (resp. repeated) definition its CondI and CondO (resp. Explode and Implode) vertices created by SynDEx when flattening the algorithm graph (cf. section 9.5). will be attached to the operation group.

8.3  To constraint operation groups on operators

Figure 8.2: Constraints on the main architecture in examples/tutorial/example7/example7.sdx

To constraint the references attached to a given operation group to be distributed onto a specific operator, you will constraint the operation groups on operators. From the Constraints menu, choose the Absolute Constraints option. Then, select the target architecture that will open a constraints window.

The Absolute Constraints on Main option does not allow you to choose the target architecture which, of course, is the architecture defined as main.

In the constraints window, left click on the target group in the left list to constraint an operation group on an operator, then left click on the target operator in the middle of the constraints window, and finally left click on the Create button. It adds the new constraint in the right list (cf. figure 8.2). Left click on the OK button to confirm your new constraint list, otherwise left click on the Cancel button.

8.4  To delete an operation group

To delete an operation group, from the Algorithm menu of the principal window, choose the Delete Operation Group option. It lists all the operation groups. Select the target group.

Chapter 9  Adequation

Performing an adequation means to execute heuristics, seeking for an optimized implementation of a given algorithm onto a given architecture, both set as “Main”.

9.1  Main algorithm and main architecture

There can be several algorithms and architectures but only one main algorithm (cf. Main mode in section 5.1.2) and one main architecture (cf. section 6.3.2) on which the adequation will be performed.

To define an algorithm as main, right click on the background of the target definition window. Choose the Set As Main Definition option. To define an architecture as main, right click on the background of the target architecture. Choose the Set As Main Architecture option

9.2  Characterization

To be able to perform an adequation, each operation and each data type of a dependence must be associated with a duration (cf. chapter 7).

You will also have to characterize additional operations generated by SynDEx in case of conditioning (cf. section 5.2) or repetition (cf. section 5.3).

9.3  To launch the adequation

To launch the adequation of the main algorithm onto the main architecture, from the Adequation menu of the principal window, choose the Launch Adequation option.

The adequation process is preceded by:

9.4  Multi-periodic applications

In case of a multi-periodic application, the flattening process is preceded by:

9.5  Flattening

Hierarchy

The main algorithm graph is transformed for the adequation to obtain a graph with a unique level of hierarchy, where each vertex is an operation in the sense of AAA (which is the same as an atomic definition in SynDEx). This transformation consists in replacing references by corresponding definitions, and paths of dependences connected along the hierarchy through ports by direct dependences between corresponding ports of the transformed operations.

Abstract references

In case of abstract references (cf. section 5.1.7), the hierarchy is not taken into account, i.e. the flattening does not go into the hierarchical referenced definitions. All the abstract references are directly replaced by operations containing the same ports as their definition. References or dependences included in those definitions are ignored.

9.6  Schedule

The schedule is displayed as sets of ordered operations infinitely repeated.

In case of a multi-periodic application, the schedule may have one or two parts. In the first case it is a permanent part displayed as sets of ordered operations infinitely repeated and in the second case it is:

SynDEx adds some Wait vertices to force the operators to satisfy the start time dates of every operation computed by the adequation according to their period.

9.6.1  To display the schedule

To view the computed distribution and schedule, from the Adequation menu, choose the Display Schedule option. It opens a window for the diagram of the real-time simulation of the algorithm executed on the architecture.

9.6.2  The schedule window

In the schedule window you will find one schedule for each operator and for each communication medium of the architecture. Each operation or communication (send/receive) is represented by a box the length of which is proportional to its duration. The operations of the transient part have a red left edge whereas the operations of the permanent part have a green left edge.

Operator

Each schedule for an operator describes a scheduling of constants, sensors, actuators, functions and delays. By default constants are not displayed. From the Window menu, choose Schedule Display Options. Then check Show Constants to change this setting.

Medium

Each schedule for a communication medium describes a scheduling of inter-operator communications, sending (resp. receiving) data from (resp. to) an operator. Note that although a communication is called “Send proc1 proc2” it is represented by a unique operation which represents the duration of the communication (send/receive) on the medium.

Start and end dates

The start date (resp. the end date) is displayed on the left edge (resp. right) of each box.

Scale

In case of big duration differences, you can disable the scale. From the Window menu, choose Schedule Display Options. Then uncheck Scale to change this setting.

Colors

When the cursor points at an operation, its box is highlighted in orange. The predecessors of the pointed operation have their boxes highlighted in green and its successors in red. Operations highlighted in pink are successors in the next repetition, rather than in the same repetition, in case of multi-periodic application.

Schedule position

Position the pointer inside the small space between two schedules of operators or between the schedule of an operator and the schedule of a communication medium then, left click and before releasing the button, drag and drop that schedule to change its position.

Warning: This feature is operational only in Vertical Display mode.

Other options

From the Window menu, choose Schedule Display Options. Check Horizontal Display to change the orientation of the display. Check Show Arrows to draw arrows between boxes which are in relation of execution precedence Uncheck Labels to not draw the names of the operations.

Chapter 10  Code generation

When the adequation has been performed, code may be generated for the main architecture.

Warning: To generate code, it is mandatory to define a processor of the main architecture as the main operator (cf. section 6.3.2).

10.1  To generate the code

From the Code menu, choose the Generate Executive(s) option. The generated .m4 files are saved in the application’s directory, one file per processor.

10.2  To view generated files

From the Code menu, choose the Display Executive(s) option.

If the option Generate m4x Files of the Code menu is checked, SynDEx also produces macro files:

The .m4x file is the only user macro file which the M4 machinery is aware of. Thus, it should include the _sdc.m4x file. The _sdc.m4x file contains M4 macro definitions corresponding to algorithm definitions that have been associated with a source code via the SynDEx code editor. This file should not be edited by hand because it is overwritten each time the user triggers code generation.

The user should put its hand-written macro definitions in the .m4x which is automatically created by SynDEx only if not already existing. If this file is created by hand, the user should be careful to include the _sdc.m4x at the beginning of the file.

10.3  Overview

In this section we give a brief summary of files you will require to generate and compile your executive files. Code generation principles will be detailed in next sections. Files required are:

For the files which are not generated by SynDEx most of the time you can simply copy existing ones (for instance from the example directory) and make modifications explained in the comments of these files. Once you gathered all these files, type make application_name.all in your shell. It compiles the executive files. Then launch the executable file of the main processor. You can also clean your directory by typing make clean.

10.4  To compile an executive

Each macro-executive source file must be first translated by the GNU M4 macro-processor, into a text file in the language preferred for the processor (usually assembler for efficiency, sometimes C or another high-level language for portability). This translation relies on several files included in the following order:

These indirected inclusions, through the names specified under SynDEx, provide a very flexible and powerful mechanism needed to support efficiently heterogeneous architectures, with heterogeneous languages and compilation chains. Then each macro-processed text file must be compiled with the adequate compiler, and linked with the adequate linker against separately compatibly-compiled application-specific files and/or processor-specific libraries, for those macros which cannot simply inline the desired code, but instead must call separately compiled codes.

10.5  To load the compiled executive

In an heterogeneous architecture, there are different compilation chains, with different executable formats which have to be transfered through different types of intermediate media and processors to be finally loaded by different boot loaders. For these reasons, a post-processor is required for each type of processor, in order to encapsulate this heterogeneity into a common download format. This is explained in more details in the downloader specification (cf. chapter 11).

10.6  To automate the compilation/load process

All processor types require the same compilation sequence, but with different compilation tools:

This compilation sequence may be automatically generated for each processor by macro-processing the macro-makefile generated by SynDEx which includes:

Although this indirect inclusion mechanism is able to generate most of the core makefile, an application-specific top makefile is still required to specify how to generate the core makefile, and to specify the compilation and linking dependencies with application-specific files (include files, separately compiled files and libraries).

Chapter 11  SynDEx downloader specification

11.1  Context

SynDEx allows the efficient programming of parallel, distributed, heterogeneous architectures, composed of several different types of processors, and of several different types of communication medium. From a user specification of an algorithm dataflow graph and of an architecture resources graph, and from algorithm and architecture characterized libraries, SynDEx automatically generates an application specific executive code for each processor, and provides a makefile to automate the compilation and linking of each executive, and its downloading into the program memory of the corresponding processor.
Separate programming of non-volatile program memories being unpractical, SynDEx considers that each processor has, for only non-volatile resident program, a boot-loader (which may be very small and simple, or may rely on a big and complex operating system) expecting an executive to be downloaded from a neighbour processor through a communication medium, except for a single host processor, designated by the name root in the specified architecture graph, which boot-loader expects all executives to be stored altogether in its local non-volatile memory.
Consequently, SynDEx computes, over the architecture graph, an oriented coverage tree rooted on the root processor, and generates in each processor executive the code needed to download the compiled executives through this tree, in a predetermined order which is also used to generate the makefile.

11.2  Boot and download process

This process is the same for all processors, except that the root processor gets executives from its local non-volatile memory, whereas all the other processors get executives from their neighbour processor which is their ascendant towards the root of the download tree. The processors which have the same ascendant processor are called the descendants of that processor.
When powered on, each processor boots by executing its resident boot-loader which gets the processor’s executive, loads it into the processor’s program memory, and executes it. During its initialization phase, the executive gets and forwards executives to all its descendants, before proceeding with application data processing.
The root processor, usually an embedded PC or other kind of workstation, bootloads from its disk an operating system which automatically loads and executes a startup program allowing the user to choose between different applications. During early developments, this program may be a simple shell (but this requires a keyboard to be available), and the user enters a make command to compile the executives if needed, and to execute the root executive, with the other executive files passed as arguments on the command line. In applications where it is unpractical to use a keyboard permanently connected, the startup program may use another input device (for example a switch or a touch screen) to let the user choose between different predefined shell commands, starting different applications through the corresponding make command, or simply launching a shell for interaction with a keyboard. In more deeply embedded applications, where the root processor has neither a disk nor an operating system, all the executives are stored in a FLASH memory, and the root processor boots by executing directly its own executive, and finds the other executives sequentially stored in its FLASH.
The first executive forwarded to a descendant is received, stored, and executed by that descendant’s boot-loader. Then, while that descendant’s executive asks for executives, the ascendant executive gets and forwards the next executives to the same descendant, until that descendant’s executive signals that it has itself no more executives to forward. Then the ascendant may switch to its next descendant, until it has no more descendant to service, and hence no more executive to forward. This fully sequential download process boots processors in the order of a depth-first traversal of the download tree.
In the case of a point-to-point medium, the descendant executive may proceed to application data communications as soon as it has no more executive to forward, whereas in the case of a multipoint medium, the descendant executive must wait until the ascendant executive signals that it has no more executive to forward (to avoid communication interferences between descendant application data and ascendant download data).

11.3  Common download format

Each processor type may have a different compiler (linker) output format, and some processor types may have a ROM-ed embedded boot-loader (firmware), with its own requirements on the download format. The SynDEx common download format encapsulates the details and the differences of the compiler output formats, and of the boot-loaders download formats; it is composed as follows:

The first executive forwarded to a descendant being received by that descendant’s boot-loader, that executive must be sent without its four bytes prefix; the following executives sent to the same descendant being forwarded by that descendant’s executive, they must be sent with their four bytes prefix.
The sequence of bytes itself must follow the format expected by the destination boot-loader. Therefore a linker post-processor must be developped for each processor type, to translate the linker output file into the SynDEx common dowload format described above. All the post-processors’ outputs will be concatenated by the makefile into a unique contiguous image (file), that the root executive will use as source.

11.4  Downloader macros

The downloader code is generated by two macros:

Processor names are usefull to address processors connected to multipoint medium: a processor name may be suffixed to give the name of a user defined macro, which substitution gives the processor address.
As executives data may be forwarded through several communication medium of different bandwidths, transfers must be synchronized such that data flow at the speed of the slowest communication medium.
Between processors, if flow control is not supported by the communication medium hardware, it must be implemented by ready to receive control messages sent by the loadFrom_ code for each chunk of data to be sent by the loadDnto_ code. Inside a processor, the loadFrom_ and loadDnto_ macro cooperation is based on the order in which the spawn_thread_ macros (one for each communication sequence, i.e. for each communication media) are generated in the initialization phase of the main_ ... endmain_ sequence: the spawn_thread_ macro corresponding to the thread_ macro of the communication sequence starting with the loadFrom_ macro (i.e. of the media connected to the ascendant processor) is called first, followed by the other spawn_thread_ macros, among which the ones, if any, corresponding to the communication sequences with a loadDnto_ macro (i.e. of the media connected to the descendant processors).
If the processor is a leaf node of the download tree, its loadFrom_ macro has only one argument; in this case, it directly generates the code sending to the ascendant processor a "null" message meaning that no more executive is requested, followed, in the case of a multipoint medium, by the code waiting for other executives to be downloaded to the other processors connected to the communication medium, until the ascendant processor sends an "empty" executive meaning that the download process is complete on this communication medium.
Otherwise, before generating the code described in the previous paragraph, the loadFrom_ macro generates a RETURN instruction (which will return control after the CALL instruction generated by the spawn_thread_ macro), followed by a loadFrom_end_: label, and the loadFrom_ macro also defines three macros for use by the loadDnto_ macros:

If the code generated by any of these three macros is limited to a few instructions, it may be generated inline, otherwise the loadFrom_ macro generates this code as a subroutine (between the RETURN instruction and the loadFrom_end_ label), and a call to that subroutine is generated instead of the inline code.

Chapter 12  Links

For more information:
SynDEx: http://www.syndex.org
AAA methodology: http://www-rocq.inria.fr/syndex/pub/execv4/execv4.pdf
Objective-Caml: http://caml.inria.fr/
Tcl/Tk: http://www.tcl.tk/
CamlTk: http://pauillac.inria.fr/camltk/

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