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#include <math.h> // for fmodf, isnan
#include <stdint.h> // for uint32_t
float fmodf(float x, float y)
{
union {
float f;
uint32_t i;
} ux = { x }, uy = { y };
int ex = ux.i >> 23 & 0xff;
int ey = uy.i >> 23 & 0xff;
uint32_t sx = ux.i & 0x80000000;
uint32_t i;
uint32_t uxi = ux.i;
if (uy.i << 1 == 0 || isnan(y) || ex == 0xff)
return (x * y) / (x * y);
if (uxi << 1 <= uy.i << 1) {
if (uxi << 1 == uy.i << 1)
return 0 * x;
return x;
}
/* normalize x and y */
if (!ex) {
for (i = uxi << 9; i >> 31 == 0; ex--, i <<= 1)
;
uxi <<= -ex + 1;
} else {
uxi &= -1U >> 9;
uxi |= 1U << 23;
}
if (!ey) {
for (i = uy.i << 9; i >> 31 == 0; ey--, i <<= 1)
;
uy.i <<= -ey + 1;
} else {
uy.i &= -1U >> 9;
uy.i |= 1U << 23;
}
/* x mod y */
for (; ex > ey; ex--) {
i = uxi - uy.i;
if (i >> 31 == 0) {
if (i == 0)
return 0 * x;
uxi = i;
}
uxi <<= 1;
}
i = uxi - uy.i;
if (i >> 31 == 0) {
if (i == 0)
return 0 * x;
uxi = i;
}
for (; uxi >> 23 == 0; uxi <<= 1, ex--)
;
/* scale result up */
if (ex > 0) {
uxi -= 1U << 23;
uxi |= (uint32_t)ex << 23;
} else {
uxi >>= -ex + 1;
}
uxi |= sx;
ux.i = uxi;
return ux.f;
}
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