125 lines
2.2 KiB
C
125 lines
2.2 KiB
C
#include "libc/math/libm.h"
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#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
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long double remquol(long double x, long double y, int *quo)
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{
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return remquo(x, y, quo);
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}
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#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
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long double remquol(long double x, long double y, int *quo)
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{
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union ldshape ux = {x}, uy = {y};
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int ex = ux.i.se & 0x7fff;
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int ey = uy.i.se & 0x7fff;
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int sx = ux.i.se >> 15;
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int sy = uy.i.se >> 15;
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uint32_t q;
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*quo = 0;
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if (y == 0 || isnan(y) || ex == 0x7fff)
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return (x*y)/(x*y);
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if (x == 0)
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return x;
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/* normalize x and y */
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if (!ex) {
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ux.i.se = ex;
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ux.f *= 0x1p120f;
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ex = ux.i.se - 120;
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}
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if (!ey) {
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uy.i.se = ey;
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uy.f *= 0x1p120f;
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ey = uy.i.se - 120;
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}
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q = 0;
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if (ex >= ey) {
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/* x mod y */
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#if LDBL_MANT_DIG == 64
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uint64_t i, mx, my;
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mx = ux.i.m;
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my = uy.i.m;
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for (; ex > ey; ex--) {
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i = mx - my;
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if (mx >= my) {
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mx = 2*i;
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q++;
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q <<= 1;
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} else if (2*mx < mx) {
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mx = 2*mx - my;
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q <<= 1;
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q++;
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} else {
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mx = 2*mx;
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q <<= 1;
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}
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}
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i = mx - my;
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if (mx >= my) {
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mx = i;
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q++;
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}
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if (mx == 0)
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ex = -120;
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else
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for (; mx >> 63 == 0; mx *= 2, ex--);
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ux.i.m = mx;
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#elif LDBL_MANT_DIG == 113
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uint64_t hi, lo, xhi, xlo, yhi, ylo;
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xhi = (ux.i2.hi & -1ULL>>16) | 1ULL<<48;
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yhi = (uy.i2.hi & -1ULL>>16) | 1ULL<<48;
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xlo = ux.i2.lo;
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ylo = ux.i2.lo;
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for (; ex > ey; ex--) {
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hi = xhi - yhi;
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lo = xlo - ylo;
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if (xlo < ylo)
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hi -= 1;
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if (hi >> 63 == 0) {
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xhi = 2*hi + (lo>>63);
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xlo = 2*lo;
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q++;
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} else {
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xhi = 2*xhi + (xlo>>63);
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xlo = 2*xlo;
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}
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q <<= 1;
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}
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hi = xhi - yhi;
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lo = xlo - ylo;
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if (xlo < ylo)
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hi -= 1;
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if (hi >> 63 == 0) {
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xhi = hi;
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xlo = lo;
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q++;
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}
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if ((xhi|xlo) == 0)
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ex = -120;
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else
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for (; xhi >> 48 == 0; xhi = 2*xhi + (xlo>>63), xlo = 2*xlo, ex--);
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ux.i2.hi = xhi;
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ux.i2.lo = xlo;
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#endif
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}
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/* scale result and decide between |x| and |x|-|y| */
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if (ex <= 0) {
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ux.i.se = ex + 120;
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ux.f *= 0x1p-120f;
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} else
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ux.i.se = ex;
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x = ux.f;
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if (sy)
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y = -y;
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if (ex == ey || (ex+1 == ey && (2*x > y || (2*x == y && q%2)))) {
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x -= y;
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q++;
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}
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q &= 0x7fffffff;
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*quo = sx^sy ? -(int)q : (int)q;
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return sx ? -x : x;
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}
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#endif
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