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circuitpython/lib/libm/fmodf.c

70 lines
1.4 KiB

/*****************************************************************************/
/*****************************************************************************/
// fmodf from musl-0.9.15
/*****************************************************************************/
/*****************************************************************************/
#include "libm.h"
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;
}