| #include <math.h> |
| #include <stdint.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; |
| } |
