gptest.c

#include <stdio.h>
// #### #### #### #### .  #### #### #### #### 
// S 15 . 16 
#define FX_Q_NUM 16
#define FX_2_MINUS_16  1.52587890625e-05F
#define FX_2_PLUS_16   (1<<16)
#define FX_S_15_16 11516
#define FX_SYSTEM  FX_S_15_16

typedef int fixed32; 

fixed32 fromFloat(float fa)
{
	return (fixed32) (fa * FX_2_PLUS_16) ; 
}

float toFloat(fixed32 xa)
{
	return ((float) (xa)) * FX_2_MINUS_16 ; 
}

fixed32 fxAdd(fixed32 a, fixed32 b)
{
	return fromFloat((toFloat(a) + toFloat(b))); 
}

fixed32 fxAdd2(fixed32 a, fixed32 b)
{
	return a+b;
}

int main()
{
	long long i=0; 
	int ia, ib, ic, ic2; 
	float fa; 
	// fscanf(stdin, "%d %d", &ia, &ib); 
	for ( i = 0; i < (long long) 256*256*256*256; i+=(256*256))
	{
		ic = fxAdd(i, i); 
		ic2 = fxAdd2(i, i); 
		fprintf(stdout, "%f + %f : %f , %f diff = %d\n", toFloat(i), toFloat(i), toFloat(ic), toFloat(ic2), ic-ic2); 
	}
	//fprintf(stdout, "%d + %d : %d\n", ia, ib , ic) ; 
	//fprintf(stdout, "%f + %f : %f\n", toFloat(ia), toFloat(ib), toFloat(ic)); 
}