August 3rd, 2010

Preliminary IQmath Natural log function.

Two libraries are included:

(a) IQmathLog.lib: This build of the library can be linked with code built for fixed-point.
(b) IQmathLog_f32.lib: This build of the library can be linked with code built with the --float_support=fpu32 switch. 
    This can be useful for mixing IQmath with native floating-point code on devices with the C28x+FPU.

This library includes only the natural log function: 

_iq   _IQlog( _iq A)      ; Q = GLOBAL_Q

_iqN  _IQNlog( _iqN A)    ; Q = 1-29


Cycles: ~148 (includes call & return)
This function does not use a lookup table.


Example:

#include "IQmathLib.h"
#include "IQlog.h"

...

main()
{
    _iq x;
    _iq y;
    
    
....
   y = _IQ(1.5);  
   x = _IQlog(y);  // x =  0.405465108
   
   
}


Example C++:
#include <stdio.h>
#include <stdlib.h>

extern "C" {
#include "IQmathLib.h"
}

extern "C" {
#include "IQlog.h"
}

#include "IQmathCPP.h"

inline iq24 IQ24log(const iq24 & x)
{
	iq24 temp;
	temp.val = _IQ24log(x.val);
	return temp;	
}


int main(void)
{
	
   iq24 	one, two;
	
    two = IQ24log(1.5);  
    one = IQ24log(two);  
    
}