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math: rewrite modf.c and clean up modff.c

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cleaner implementation with unions and unsigned arithmetic
This commit is contained in:
nsz
2012-03-29 14:03:18 +02:00
parent 9f58d06007
commit f6ceccd922
2 changed files with 45 additions and 72 deletions
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28
src/math/modff.c
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@ -1,33 +1,37 @@
#include "libm.h"
#include <math.h>
#include <stdint.h>
float modff(float x, float *iptr)
{
uint32_t u, mask;
union {float x; uint32_t n;} u = {x};
uint32_t mask;
int e;
GET_FLOAT_WORD(u, x);
e = (int)(u>>23 & 0xff) - 0x7f;
e = (int)(u.n>>23 & 0xff) - 0x7f;
/* no fractional part */
if (e >= 23) {
*iptr = x;
if (e == 0x80 && u<<9 != 0) /* nan */
if (e == 0x80 && u.n<<9 != 0) { /* nan */
return x;
SET_FLOAT_WORD(x, u & 0x80000000);
return x;
}
u.n &= 0x80000000;
return u.x;
}
/* no integral part */
if (e < 0) {
SET_FLOAT_WORD(*iptr, u & 0x80000000);
u.n &= 0x80000000;
*iptr = u.x;
return x;
}
mask = 0x007fffff>>e;
if ((u & mask) == 0) {
if ((u.n & mask) == 0) {
*iptr = x;
SET_FLOAT_WORD(x, u & 0x80000000);
return x;
u.n &= 0x80000000;
return u.x;
}
SET_FLOAT_WORD(*iptr, u & ~mask);
u.n &= ~mask;
*iptr = u.x;
return x - *iptr;
}