Texas Instruments TMS320 DSP manual Relocatability, Example

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TMS320C55x Rules and Guidelines

Rule 32

All C55x algorithms must access all static and global data as far data; also, the algorithms should be instantiable in a large memory model.

5.5.3 Program Models

Only the large memory model is supported for the program memory. So there are no special program memory requirements for this processor. Just to reemphasize the point, all the program code must be completely relocatable and must not necessarily require placement in on-chip memory.

Rule 33

C55x algorithms must never assume placement in on-chip program memory; i.e., they must properly operate with program memory operated in instruction cache mode.

The above rule can be interpreted as to the algorithm code must not have any assumptions on the timing information to guarantee the functionality.

5.5.4 Relocatability

Some of the C55X devices have a constraint that the data accessed with the B-bus (coefficient addressing) must come from on-chip memory. The data that is accessed by B-bus can be static-data or heap-data. All C55x algorithms that access data (static or heap) with the B-bus must adhere to the following rule.

Rule 34

All C55x algorithms that access data by B-bus must document:

∙the instance number of the IALG_MemRec structure that is accessed by the B-bus (heap-data), and

∙the data-section name that is accessed by the B-bus (static-data).

Example 1

Int algAlloc(IALG_Params *algParams, IALG_Fxns **p,

IALG_MemRec memTab[])

{

EncoderParams *params = (EncoderParams *)algParams; If (params == NULL) {

params = &ENCODERATTRS;

}

memTab[0].size = sizeof (EncoderObj);

...

memTab[1].size = params->frameDuration * 8 * sizeof(int);

...

memTab[3].size = params->sizeInBytes;

...

return (2);

}

Suppose, in the above example, the memTab[1] and memTab[3] are accessed by the B-bus. Then this must be documented as per the Rule 34 as follows:

Number of memTab blocks that are accessed by B-bus	Block numbers
2	1,3

SPRU352G –June 2005 –Revised February 2007 DSP-Specific Guidelines 53

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