IQmath Library

3.3. Calling a IQmath Function from C
In addition to installing the IQmath software, to include a IQmath function in your code you
have to:
q
q
q
q
Include the IQmathLib.h include file
Link your code with the IQmath object code library, IQmath.lib.
Use a correct linker command file to place “IQmath” section in program memory
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 /* Header file for IQmath routine */
#define PI 3.14159
_iq input, sin_out;
void main(void )
{
input=_IQ29(0.25*PI); /* 0.25×
π radians represented in Q29 format */
sin_out =_IQ29sin(input);
}
©Texas Instruments Inc., June 2002 5