PM0014 datasheet(11/46 Pages) STMICROELECTRONICS

11 / 46 page

PM0014

Using the ST10-DSP library

11/46

3.10.2

Memory reservations

Filtering functions and spectral functions have to allocate data in DP-RAM (See Section 2.1

Performance considerations on page 7). There are several means to do that.

●

The easiest is certainly to declare theses variables as global and to use iram directive:

Example:

iram short DelayLine[NumberCoeffs]

...

void main()

{...}

●

If you want this variable to be local, you have to declare the variable as a static one and

use the iram directive.

Example:

static _iram Delayline[NumberCoeffs];

3.10.3

Memory model aspects

TINY and SMALL models

Library function’s argument can not be stored as far data (use only near data).

MEDIUM and LARGE models

The arguments of the function must be in the same memory page. In fact, the same Data

Page Pointer is used for all the arguments of the function.

E.g.: add_16(a,b,&c)

a and b are located in the same data page

An argument that is a pointer must be an address contained in the same Data Page than the

other arguments.

E.g.1: c is located in the same data page than a and b.

E.g. 2: firq15_q15_q15(&fir) where:

●

fir.CoeffPtr is a pointer

●

fir.DelayLinePtr is a pointer

fir.CoeffPtr and fir.DelayLinePtr must address data in the same page. As fir.DelayLinePtr

must be located in DPRAM, it could be a solution to map RAM in the same page than

DPRAM (generally page number 3).

PM0014 Datasheet(PDF) 11 Page - STMicroelectronics