| #include <math.h> |
| #include <stdint.h> |
| |
| double remquo(double x, double y, int* quo) { |
| union { |
| double f; |
| uint64_t i; |
| } ux = {x}, uy = {y}; |
| int ex = ux.i >> 52 & 0x7ff; |
| int ey = uy.i >> 52 & 0x7ff; |
| int sx = ux.i >> 63; |
| int sy = uy.i >> 63; |
| uint32_t q; |
| uint64_t i; |
| uint64_t uxi = ux.i; |
| |
| *quo = 0; |
| if (uy.i << 1 == 0 || isnan(y) || ex == 0x7ff) |
| return (x * y) / (x * y); |
| if (ux.i << 1 == 0) |
| return x; |
| |
| /* normalize x and y */ |
| if (!ex) { |
| for (i = uxi << 12; i >> 63 == 0; ex--, i <<= 1) |
| ; |
| uxi <<= -ex + 1; |
| } else { |
| uxi &= -1ULL >> 12; |
| uxi |= 1ULL << 52; |
| } |
| if (!ey) { |
| for (i = uy.i << 12; i >> 63 == 0; ey--, i <<= 1) |
| ; |
| uy.i <<= -ey + 1; |
| } else { |
| uy.i &= -1ULL >> 12; |
| uy.i |= 1ULL << 52; |
| } |
| |
| q = 0; |
| if (ex < ey) { |
| if (ex + 1 == ey) |
| goto end; |
| return x; |
| } |
| |
| /* x mod y */ |
| for (; ex > ey; ex--) { |
| i = uxi - uy.i; |
| if (i >> 63 == 0) { |
| uxi = i; |
| q++; |
| } |
| uxi <<= 1; |
| q <<= 1; |
| } |
| i = uxi - uy.i; |
| if (i >> 63 == 0) { |
| uxi = i; |
| q++; |
| } |
| if (uxi == 0) |
| ex = -60; |
| else |
| for (; uxi >> 52 == 0; uxi <<= 1, ex--) |
| ; |
| end: |
| /* scale result and decide between |x| and |x|-|y| */ |
| if (ex > 0) { |
| uxi -= 1ULL << 52; |
| uxi |= (uint64_t)ex << 52; |
| } else { |
| uxi >>= -ex + 1; |
| } |
| ux.i = uxi; |
| x = ux.f; |
| if (sy) |
| y = -y; |
| if (ex == ey || (ex + 1 == ey && (2 * x > y || (2 * x == y && q % 2)))) { |
| x -= y; |
| q++; |
| } |
| q &= 0x7fffffff; |
| *quo = sx ^ sy ? -(int)q : (int)q; |
| return sx ? -x : x; |
| } |
