1#include <math.h> 2#include <stdint.h> 3 4float fmodf(float x, float y) { 5 union { 6 float f; 7 uint32_t i; 8 } ux = {x}, uy = {y}; 9 int ex = ux.i >> 23 & 0xff; 10 int ey = uy.i >> 23 & 0xff; 11 uint32_t sx = ux.i & 0x80000000; 12 uint32_t i; 13 uint32_t uxi = ux.i; 14 15 if (uy.i << 1 == 0 || isnan(y) || ex == 0xff) 16 return (x * y) / (x * y); 17 if (uxi << 1 <= uy.i << 1) { 18 if (uxi << 1 == uy.i << 1) 19 return 0 * x; 20 return x; 21 } 22 23 /* normalize x and y */ 24 if (!ex) { 25 for (i = uxi << 9; i >> 31 == 0; ex--, i <<= 1) 26 ; 27 uxi <<= -ex + 1; 28 } else { 29 uxi &= -1U >> 9; 30 uxi |= 1U << 23; 31 } 32 if (!ey) { 33 for (i = uy.i << 9; i >> 31 == 0; ey--, i <<= 1) 34 ; 35 uy.i <<= -ey + 1; 36 } else { 37 uy.i &= -1U >> 9; 38 uy.i |= 1U << 23; 39 } 40 41 /* x mod y */ 42 for (; ex > ey; ex--) { 43 i = uxi - uy.i; 44 if (i >> 31 == 0) { 45 if (i == 0) 46 return 0 * x; 47 uxi = i; 48 } 49 uxi <<= 1; 50 } 51 i = uxi - uy.i; 52 if (i >> 31 == 0) { 53 if (i == 0) 54 return 0 * x; 55 uxi = i; 56 } 57 for (; uxi >> 23 == 0; uxi <<= 1, ex--) 58 ; 59 60 /* scale result up */ 61 if (ex > 0) { 62 uxi -= 1U << 23; 63 uxi |= (uint32_t)ex << 23; 64 } else { 65 uxi >>= -ex + 1; 66 } 67 uxi |= sx; 68 ux.i = uxi; 69 return ux.f; 70} 71