diff options
Diffstat (limited to 'src/math/fmodl.c')
| -rw-r--r-- | src/math/fmodl.c | 213 |
1 files changed, 80 insertions, 133 deletions
diff --git a/src/math/fmodl.c b/src/math/fmodl.c index b930c49d..54af6a3f 100644 --- a/src/math/fmodl.c +++ b/src/math/fmodl.c @@ -1,15 +1,3 @@ -/* origin: FreeBSD /usr/src/lib/msun/src/e_fmodl.c */ -/*- - * ==================================================== - * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. - * - * Developed at SunSoft, a Sun Microsystems, Inc. business. - * Permission to use, copy, modify, and distribute this - * software is freely granted, provided that this notice - * is preserved. - * ==================================================== - */ - #include "libm.h" #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024 @@ -18,141 +6,100 @@ long double fmodl(long double x, long double y) return fmod(x, y); } #elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384 - -#define BIAS (LDBL_MAX_EXP - 1) - -#if LDBL_MANL_SIZE > 32 -typedef uint64_t manl_t; -#else -typedef uint32_t manl_t; -#endif - -#if LDBL_MANH_SIZE > 32 -typedef uint64_t manh_t; -#else -typedef uint32_t manh_t; -#endif - -/* - * These macros add and remove an explicit integer bit in front of the - * fractional mantissa, if the architecture doesn't have such a bit by - * default already. - */ -#ifdef LDBL_IMPLICIT_NBIT -#define SET_NBIT(hx) ((hx) | (1ULL << LDBL_MANH_SIZE)) -#define HFRAC_BITS LDBL_MANH_SIZE -#else -#define SET_NBIT(hx) (hx) -#define HFRAC_BITS (LDBL_MANH_SIZE - 1) -#endif - -#define MANL_SHIFT (LDBL_MANL_SIZE - 1) - -static const long double Zero[] = {0.0, -0.0,}; - -/* - * fmodl(x,y) - * Return x mod y in exact arithmetic - * Method: shift and subtract - * - * Assumptions: - * - The low part of the mantissa fits in a manl_t exactly. - * - The high part of the mantissa fits in an int64_t with enough room - * for an explicit integer bit in front of the fractional bits. - */ long double fmodl(long double x, long double y) { - union IEEEl2bits ux, uy; - int64_t hx,hz; /* We need a carry bit even if LDBL_MANH_SIZE is 32. */ - manh_t hy; - manl_t lx,ly,lz; - int ix,iy,n,sx; - - ux.e = x; - uy.e = y; - sx = ux.bits.sign; + union ldshape ux = {x}, uy = {y}; + int ex = ux.i.se & 0x7fff; + int ey = uy.i.se & 0x7fff; + int sx = ux.i.se & 0x8000; - /* purge off exception values */ - if ((uy.bits.exp|uy.bits.manh|uy.bits.manl) == 0 || /* y=0 */ - ux.bits.exp == BIAS + LDBL_MAX_EXP || /* or x not finite */ - (uy.bits.exp == BIAS + LDBL_MAX_EXP && - ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0)) /* or y is NaN */ + if (y == 0 || isnan(y) || ex == 0x7fff) return (x*y)/(x*y); - if (ux.bits.exp <= uy.bits.exp) { - if (ux.bits.exp < uy.bits.exp || - (ux.bits.manh<=uy.bits.manh && - (ux.bits.manh<uy.bits.manh || - ux.bits.manl<uy.bits.manl))) /* |x|<|y| return x or x-y */ - return x; - if (ux.bits.manh==uy.bits.manh && ux.bits.manl==uy.bits.manl) - return Zero[sx]; /* |x| = |y| return x*0 */ + ux.i.se = ex; + uy.i.se = ey; + if (ux.f <= uy.f) { + if (ux.f == uy.f) + return 0*x; + return x; } - /* determine ix = ilogb(x) */ - if (ux.bits.exp == 0) { /* subnormal x */ - ux.e *= 0x1.0p512; - ix = ux.bits.exp - (BIAS + 512); - } else { - ix = ux.bits.exp - BIAS; + /* normalize x and y */ + if (!ex) { + ux.f *= 0x1p120f; + ex = ux.i.se - 120; } - - /* determine iy = ilogb(y) */ - if (uy.bits.exp == 0) { /* subnormal y */ - uy.e *= 0x1.0p512; - iy = uy.bits.exp - (BIAS + 512); - } else { - iy = uy.bits.exp - BIAS; + if (!ey) { + uy.f *= 0x1p120f; + ey = uy.i.se - 120; } - /* set up {hx,lx}, {hy,ly} and align y to x */ - hx = SET_NBIT(ux.bits.manh); - hy = SET_NBIT(uy.bits.manh); - lx = ux.bits.manl; - ly = uy.bits.manl; - - /* fix point fmod */ - n = ix - iy; - - while (n--) { - hz = hx-hy; - lz = lx-ly; - if (lx < ly) - hz -= 1; - if (hz < 0) { - hx = hx+hx+(lx>>MANL_SHIFT); - lx = lx+lx; + /* x mod y */ +#if LDBL_MANT_DIG == 64 + uint64_t i, mx, my; + mx = ux.i.m; + my = uy.i.m; + for (; ex > ey; ex--) { + i = mx - my; + if (mx >= my) { + if (i == 0) + return 0*x; + mx = 2*i; + } else if (2*mx < mx) { + mx = 2*mx - my; } else { - if ((hz|lz)==0) /* return sign(x)*0 */ - return Zero[sx]; - hx = hz+hz+(lz>>MANL_SHIFT); - lx = lz+lz; + mx = 2*mx; } } - hz = hx-hy; - lz = lx-ly; - if (lx < ly) - hz -= 1; - if (hz >= 0) { - hx = hz; - lx = lz; + i = mx - my; + if (mx >= my) { + if (i == 0) + return 0*x; + mx = i; } - - /* convert back to floating value and restore the sign */ - if ((hx|lx) == 0) /* return sign(x)*0 */ - return Zero[sx]; - while (hx < (1ULL<<HFRAC_BITS)) { /* normalize x */ - hx = hx+hx+(lx>>MANL_SHIFT); - lx = lx+lx; - iy -= 1; + for (; mx >> 63 == 0; mx *= 2, ex--); + ux.i.m = mx; +#elif LDBL_MANT_DIG == 113 + uint64_t hi, lo, xhi, xlo, yhi, ylo; + xhi = (ux.i2.hi & -1ULL>>16) | 1ULL<<48; + yhi = (uy.i2.hi & -1ULL>>16) | 1ULL<<48; + xlo = ux.i2.lo; + ylo = ux.i2.lo; + for (; ex > ey; ex--) { + hi = xhi - yhi; + lo = xlo - ylo; + if (xlo < ylo) + hi -= 1; + if (hi >> 63 == 0) { + if ((hi|lo) == 0) + return 0*x; + xhi = 2*hi + (lo>>63); + xlo = 2*lo; + } else { + xhi = 2*xhi + (xlo>>63); + xlo = 2*xlo; + } } - ux.bits.manh = hx; /* The mantissa is truncated here if needed. */ - ux.bits.manl = lx; - if (iy < LDBL_MIN_EXP) { - ux.bits.exp = iy + (BIAS + 512); - ux.e *= 0x1p-512; - } else { - ux.bits.exp = iy + BIAS; + hi = xhi - yhi; + lo = xlo - ylo; + if (xlo < ylo) + hi -= 1; + if (hi >> 63 == 0) { + if ((hi|lo) == 0) + return 0*x; + xhi = hi; + xlo = lo; } - return ux.e; /* exact output */ + for (; xhi >> 48 == 0; xhi = 2*xhi + (xlo>>63), xlo = 2*xlo, ex--); + ux.i2.hi = xhi; + ux.i2.lo = xlo; +#endif + + /* scale result */ + if (ex <= 0) { + ux.i.se = (ex+120)|sx; + ux.f *= 0x1p-120f; + } else + ux.i.se = ex|sx; + return ux.f; } #endif |