原创 IOMath库的使用

1. Include the IQmathLib.h include file<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

2. Link your code with the IQmath object code library, IQmath.lib.

3. Use a correct linker command file to place “IQmath” section in program memory

4. The section “IQmathTables” contains look-up tables for IQmath functions and it is

available in the BOOTROM of F2810/F2812 devices. Hence, this section must be of set

to “NOLOAD” type in the linker command. This facilitates referencing look-up table

symbols, without actually loading the section into the target.

Note:

IQmath functions are assembled in ”IQmath” section & the look -up tables used to

perform high precision computation are placed in “IQmathTables” section.

IQmath Linker Command File (F28x device):

MEMORY

{

PAGE 0:

BOOTROM (RW) : origin = 0x3ff000, length = 0x000fc0

RAMH0 (RW) : origin = 0x3f8000, length = 0x002000

}

SECTIONS

{

IQmathTables : load = BOOTROM, type = NOLOAD, PAGE = 0

IQmath : load = RAMH0, PAGE = 0

}

For example, the following code contains a call to the IQ25sin routines in IQmath Library:

#include<IQmathLib.h> /* Header file for IQmath routine */

#define PI 3.14159

_iq input, sin_out;

void main(void )

{

input=_IQ29(0.25*PI); /* p ′ 25 . 0 radians represented in Q29 format */

sin_out =_IQ29sin(input);

}

5.  Selecting GLOBAL_Q format

CASE I:

Default GLOBAL_Q format is set to Q24. Edit “IQmathLib.h” header file to modify this

value as required, user can choose from Q1 to Q29 as GLOBAL_Q format. Note that

modifying this value means that all the GLOBAL_Q functions will use this Q format for

input/output, unless this symbolic definition is overridden in the source code.

#ifndef GLOBAL_Q

#define GLOBAL_Q 24 /* Q1 to Q29 */

#endif

CASE II :

A complete system consists of various modules. Some modules may require different

precision, then the rest of the system. In such situation, we need to over-ride the

GLOBAL_Q defined in the “IQmathLib.h” file and use the local Q format.

This can be easily done by defining the GLOBAL_Q constant in the source file of the

module before the include statement.

#define GLOBAL_Q 27 /* Set the Local Q value */

#include <IQmathLib.h>