diff options
Diffstat (limited to 'libc-top-half/musl/src/math/__rem_pio2l.c')
| -rw-r--r-- | libc-top-half/musl/src/math/__rem_pio2l.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/libc-top-half/musl/src/math/__rem_pio2l.c b/libc-top-half/musl/src/math/__rem_pio2l.c new file mode 100644 index 0000000..e73a86b --- /dev/null +++ b/libc-top-half/musl/src/math/__rem_pio2l.c @@ -0,0 +1,159 @@ +/* origin: FreeBSD /usr/src/lib/msun/ld80/e_rem_pio2.c */ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * Copyright (c) 2008 Steven G. Kargl, David Schultz, Bruce D. Evans. + * + * 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. + * ==================================================== + * + * Optimized by Bruce D. Evans. + */ +#include "libm.h" +#if (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384 +/* ld80 and ld128 version of __rem_pio2(x,y) + * + * return the remainder of x rem pi/2 in y[0]+y[1] + * use __rem_pio2_large() for large x + */ + +static const long double toint = 1.5/LDBL_EPSILON; + +#if LDBL_MANT_DIG == 64 +/* u ~< 0x1p25*pi/2 */ +#define SMALL(u) (((u.i.se & 0x7fffU)<<16 | u.i.m>>48) < ((0x3fff + 25)<<16 | 0x921f>>1 | 0x8000)) +#define QUOBITS(x) ((uint32_t)(int32_t)x & 0x7fffffff) +#define ROUND1 22 +#define ROUND2 61 +#define NX 3 +#define NY 2 +/* + * invpio2: 64 bits of 2/pi + * pio2_1: first 39 bits of pi/2 + * pio2_1t: pi/2 - pio2_1 + * pio2_2: second 39 bits of pi/2 + * pio2_2t: pi/2 - (pio2_1+pio2_2) + * pio2_3: third 39 bits of pi/2 + * pio2_3t: pi/2 - (pio2_1+pio2_2+pio2_3) + */ +static const double +pio2_1 = 1.57079632679597125389e+00, /* 0x3FF921FB, 0x54444000 */ +pio2_2 = -1.07463465549783099519e-12, /* -0x12e7b967674000.0p-92 */ +pio2_3 = 6.36831716351370313614e-25; /* 0x18a2e037074000.0p-133 */ +static const long double +pio4 = 0x1.921fb54442d1846ap-1L, +invpio2 = 6.36619772367581343076e-01L, /* 0xa2f9836e4e44152a.0p-64 */ +pio2_1t = -1.07463465549719416346e-12L, /* -0x973dcb3b399d747f.0p-103 */ +pio2_2t = 6.36831716351095013979e-25L, /* 0xc51701b839a25205.0p-144 */ +pio2_3t = -2.75299651904407171810e-37L; /* -0xbb5bf6c7ddd660ce.0p-185 */ +#elif LDBL_MANT_DIG == 113 +/* u ~< 0x1p45*pi/2 */ +#define SMALL(u) (((u.i.se & 0x7fffU)<<16 | u.i.top) < ((0x3fff + 45)<<16 | 0x921f)) +#define QUOBITS(x) ((uint32_t)(int64_t)x & 0x7fffffff) +#define ROUND1 51 +#define ROUND2 119 +#define NX 5 +#define NY 3 +static const long double +#ifdef __wasilibc_unmodified_upstream // Wasm doesn't have alternate rounding modes +pio4 = 0x1.921fb54442d18469898cc51701b8p-1L, +#endif +invpio2 = 6.3661977236758134307553505349005747e-01L, /* 0x145f306dc9c882a53f84eafa3ea6a.0p-113 */ +pio2_1 = 1.5707963267948966192292994253909555e+00L, /* 0x1921fb54442d18469800000000000.0p-112 */ +pio2_1t = 2.0222662487959507323996846200947577e-21L, /* 0x13198a2e03707344a4093822299f3.0p-181 */ +pio2_2 = 2.0222662487959507323994779168837751e-21L, /* 0x13198a2e03707344a400000000000.0p-181 */ +pio2_2t = 2.0670321098263988236496903051604844e-43L, /* 0x127044533e63a0105df531d89cd91.0p-254 */ +pio2_3 = 2.0670321098263988236499468110329591e-43L, /* 0x127044533e63a0105e00000000000.0p-254 */ +pio2_3t = -2.5650587247459238361625433492959285e-65L; /* -0x159c4ec64ddaeb5f78671cbfb2210.0p-327 */ +#endif + +int __rem_pio2l(long double x, long double *y) +{ + union ldshape u,uz; + long double z,w,t,r,fn; + double tx[NX],ty[NY]; + int ex,ey,n,i; + + u.f = x; + ex = u.i.se & 0x7fff; + if (SMALL(u)) { + /* rint(x/(pi/2)) */ + fn = x*invpio2 + toint - toint; + n = QUOBITS(fn); + r = x-fn*pio2_1; + w = fn*pio2_1t; /* 1st round good to 102/180 bits (ld80/ld128) */ +#ifdef __wasilibc_unmodified_upstream // Wasm doesn't have alternate rounding modes + /* Matters with directed rounding. */ + if (predict_false(r - w < -pio4)) { + n--; + fn--; + r = x - fn*pio2_1; + w = fn*pio2_1t; + } else if (predict_false(r - w > pio4)) { + n++; + fn++; + r = x - fn*pio2_1; + w = fn*pio2_1t; + } +#endif + y[0] = r-w; + u.f = y[0]; + ey = u.i.se & 0x7fff; + if (ex - ey > ROUND1) { /* 2nd iteration needed, good to 141/248 (ld80/ld128) */ + t = r; + w = fn*pio2_2; + r = t-w; + w = fn*pio2_2t-((t-r)-w); + y[0] = r-w; + u.f = y[0]; + ey = u.i.se & 0x7fff; + if (ex - ey > ROUND2) { /* 3rd iteration, good to 180/316 bits */ + t = r; /* will cover all possible cases (not verified for ld128) */ + w = fn*pio2_3; + r = t-w; + w = fn*pio2_3t-((t-r)-w); + y[0] = r-w; + } + } + y[1] = (r - y[0]) - w; + return n; + } + /* + * all other (large) arguments + */ + if (ex == 0x7fff) { /* x is inf or NaN */ + y[0] = y[1] = x - x; + return 0; + } + /* set z = scalbn(|x|,-ilogb(x)+23) */ + uz.f = x; + uz.i.se = 0x3fff + 23; + z = uz.f; + for (i=0; i < NX - 1; i++) { + tx[i] = (double)(int32_t)z; + z = (z-tx[i])*0x1p24; + } + tx[i] = z; + while (tx[i] == 0) + i--; + n = __rem_pio2_large(tx, ty, ex-0x3fff-23, i+1, NY); + w = ty[1]; + if (NY == 3) + w += ty[2]; + r = ty[0] + w; + /* TODO: for ld128 this does not follow the recommendation of the + comments of __rem_pio2_large which seem wrong if |ty[0]| > |ty[1]+ty[2]| */ + w -= r - ty[0]; + if (u.i.se >> 15) { + y[0] = -r; + y[1] = -w; + return -n; + } + y[0] = r; + y[1] = w; + return n; +} +#endif |