float_to_exp.c File Reference

#include <stdio.h>
#include "rle.h"
#include <math.h>

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Functions
void	float_to_exp (int count, float *floats, rle_pixel *pixels)

Function Documentation

void float_to_exp	(	int	count,
		float *	floats,
		rle_pixel *	pixels
	)

Definition at line 42 of file float_to_exp.c.

{
    register int i;
    int expon, max_exp = -2000;
    float * fptr = floats;
    double f_exp;

    /* Find largest exponent */
    /* Use "Block normalization":
     * ExpScan[x] is largest exponent of the three
     * color components.  Red/Grn/BluScan[1..3] are the
     * normalized color components.
     */

    for (i = 0; i < count; i++)
    {
    frexp( *fptr++, &expon );
    max_exp = (expon > max_exp) ? expon : max_exp;
    }

    /* Don't over/underflow */
    if (max_exp > 128) max_exp = 128;
    else
    if (max_exp < -127) max_exp = -127;

    f_exp = ldexp( 256.0, -max_exp );

    fptr = floats;
    for( i = 0; i < count; i++ )  /* Extra casts for broken HP compiler */
        *pixels++ = (rle_pixel) ((int)(*fptr++ * f_exp)); 

    /* Excess 127 exponent */
    *pixels = (rle_pixel) (max_exp + 127); 
}