diff options
Diffstat (limited to 'sysdeps/ieee754/flt-32/e_log10f.c')
| -rw-r--r-- | sysdeps/ieee754/flt-32/e_log10f.c | 196 |
1 files changed, 152 insertions, 44 deletions
diff --git a/sysdeps/ieee754/flt-32/e_log10f.c b/sysdeps/ieee754/flt-32/e_log10f.c index 791895e042..058ce31f09 100644 --- a/sysdeps/ieee754/flt-32/e_log10f.c +++ b/sysdeps/ieee754/flt-32/e_log10f.c @@ -1,54 +1,162 @@ -/* e_log10f.c -- float version of e_log10.c. - */ - -/* - * ==================================================== - * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. - * - * Developed at SunPro, a Sun Microsystems, Inc. business. - * Permission to use, copy, modify, and distribute this - * software is freely granted, provided that this notice - * is preserved. - * ==================================================== - */ +/* Correctly-rounded radix-10 logarithm function for binary32 value. + +Copyright (c) 2022-2023 Alexei Sibidanov. + +This file is part of the CORE-MATH project +project (file src/binary32/log10/log10f.c, revision bc385c2). + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. +*/ #include <math.h> -#include <math_private.h> -#include <fix-int-fp-convert-zero.h> +#include <stdint.h> #include <libm-alias-finite.h> +#include "math_config.h" -static const float -two25 = 3.3554432000e+07, /* 0x4c000000 */ -ivln10 = 4.3429449201e-01, /* 0x3ede5bd9 */ -log10_2hi = 3.0102920532e-01, /* 0x3e9a2080 */ -log10_2lo = 7.9034151668e-07; /* 0x355427db */ +static __attribute__ ((noinline)) float +as_special (float x) +{ + uint32_t ux = asuint (x); + if (ux == 0x7f800000u) + return x; /* +inf */ + uint32_t ax = ux << 1; + if (ax == 0u) + { /* -0.0 */ + __math_divzerof (1); + } + if (ax > 0xff000000u) + return x + x; /* nan */ + return __math_invalidf (x); +} float -__ieee754_log10f(float x) +__ieee754_log10f (float x) { - float y,z; - int32_t i,k,hx; - - GET_FLOAT_WORD(hx,x); - - k=0; - if (hx < 0x00800000) { /* x < 2**-126 */ - if (__builtin_expect((hx&0x7fffffff)==0, 0)) - return -two25/fabsf (x); /* log(+-0)=-inf */ - if (__builtin_expect(hx<0, 0)) - return (x-x)/(x-x); /* log(-#) = NaN */ - k -= 25; x *= two25; /* subnormal number, scale up x */ - GET_FLOAT_WORD(hx,x); + static const double tr[] = + { + 0x1p+0, 0x1.f81f82p-1, 0x1.f07c1fp-1, 0x1.e9131acp-1, + 0x1.e1e1e1ep-1, 0x1.dae6077p-1, 0x1.d41d41dp-1, 0x1.cd85689p-1, + 0x1.c71c71cp-1, 0x1.c0e0704p-1, 0x1.bacf915p-1, 0x1.b4e81b5p-1, + 0x1.af286bdp-1, 0x1.a98ef6p-1, 0x1.a41a41ap-1, 0x1.9ec8e95p-1, + 0x1.999999ap-1, 0x1.948b0fdp-1, 0x1.8f9c19p-1, 0x1.8acb90fp-1, + 0x1.8618618p-1, 0x1.8181818p-1, 0x1.7d05f41p-1, 0x1.78a4c81p-1, + 0x1.745d174p-1, 0x1.702e05cp-1, 0x1.6c16c17p-1, 0x1.6816817p-1, + 0x1.642c859p-1, 0x1.605816p-1, 0x1.5c9882cp-1, 0x1.58ed231p-1, + 0x1.5555555p-1, 0x1.51d07ebp-1, 0x1.4e5e0a7p-1, 0x1.4afd6ap-1, + 0x1.47ae148p-1, 0x1.446f865p-1, 0x1.4141414p-1, 0x1.3e22cbdp-1, + 0x1.3b13b14p-1, 0x1.3813814p-1, 0x1.3521cfbp-1, 0x1.323e34ap-1, + 0x1.2f684bep-1, 0x1.2c9fb4ep-1, 0x1.29e412ap-1, 0x1.27350b9p-1, + 0x1.2492492p-1, 0x1.21fb781p-1, 0x1.1f7047ep-1, 0x1.1cf06aep-1, + 0x1.1a7b961p-1, 0x1.1811812p-1, 0x1.15b1e5fp-1, 0x1.135c811p-1, + 0x1.1111111p-1, 0x1.0ecf56cp-1, 0x1.0c9715p-1, 0x1.0a6810ap-1, + 0x1.0842108p-1, 0x1.0624dd3p-1, 0x1.041041p-1, 0x1.0204081p-1, + 0.5 + }; + static const double tl[] = + { + -0x1.d45fd6237ebe3p-47, 0x1.b947689311b6ep-8, 0x1.b5e909c96d7d5p-7, + 0x1.45f4f59ed2165p-6, 0x1.af5f92cbd8f1ep-6, 0x1.0ba01a606de8cp-5, + 0x1.3ed119b9a2b7bp-5, 0x1.714834298eec2p-5, 0x1.a30a9d98357fbp-5, + 0x1.d41d512670813p-5, 0x1.02428c0f65519p-4, 0x1.1a23444eecc3ep-4, + 0x1.31b30543f4cb4p-4, 0x1.48f3ed39bfd04p-4, 0x1.5fe8049a0e423p-4, + 0x1.769140a6aa008p-4, 0x1.8cf1836c98cb3p-4, 0x1.a30a9d55541a1p-4, + 0x1.b8de4d1ee823ep-4, 0x1.ce6e4202ca2e6p-4, 0x1.e3bc1accace07p-4, + 0x1.f8c9683b5abd4p-4, 0x1.06cbd68ca9a6ep-3, 0x1.11142f19df73p-3, + 0x1.1b3e71fa7a97fp-3, 0x1.254b4d37a46e3p-3, 0x1.2f3b6912cbf07p-3, + 0x1.390f683115886p-3, 0x1.42c7e7fffc5a8p-3, 0x1.4c65808c78d3cp-3, + 0x1.55e8c50751c55p-3, 0x1.5f52445dec3d8p-3, 0x1.68a288c3f12p-3, + 0x1.71da17bdf0d19p-3, 0x1.7af973608afd9p-3, 0x1.84011952a2579p-3, + 0x1.8cf1837a7ea6p-3, 0x1.95cb2891e43d6p-3, 0x1.9e8e7b0f869ep-3, + 0x1.a73beaa5db18dp-3, 0x1.afd3e394558d3p-3, 0x1.b856cf060d9f1p-3, + 0x1.c0c5134de1ffcp-3, 0x1.c91f1371bc99fp-3, 0x1.d1652ffcd3f53p-3, + 0x1.d997c6f635e75p-3, 0x1.e1b733ab90f3bp-3, 0x1.e9c3ceadac856p-3, + 0x1.f1bdeec43a305p-3, 0x1.f9a5e7a5fa3fep-3, 0x1.00be05ac02f2bp-2, + 0x1.04a054d81a2d4p-2, 0x1.087a0835957fbp-2, 0x1.0c4b457099517p-2, + 0x1.101431aa1fe51p-2, 0x1.13d4f08b98dd8p-2, 0x1.178da53edb892p-2, + 0x1.1b3e71e9f9d58p-2, 0x1.1ee777defdeedp-2, 0x1.2288d7b48e23bp-2, + 0x1.2622b0f52e49fp-2, 0x1.29b522a4c6314p-2, 0x1.2d404b0e30f8p-2, + 0x1.30c4478f3fbe5p-2, 0x1.34413509f7915p-2 + }; + static const union + { + float f; + uint32_t u; + } st[] = + { + { 0x1p+0 }, { 0x1.4p+3 }, { 0x1.9p+6 }, { 0x1.f4p+9 }, + { 0x1.388p+13 }, { 0x1.86ap+16 }, { 0x1.e848p+19 }, { 0x1.312dp+23 }, + { 0x1.7d784p+26 }, { 0x1.dcd65p+29 }, { 0x1.2a05f2p+33 }, { 0 }, + { 0 }, { 0 }, { 0 }, { 0 } + }; + static const double b[] = + { + 0x1.bcb7b15c5a2f8p-2, -0x1.bcbb1dbb88ebap-3, 0x1.2871c39d521c6p-3 + }; + static const double c[] = + { + 0x1.bcb7b1526e50ep-2, -0x1.bcb7b1526e53dp-3, 0x1.287a7636f3fa2p-3, + -0x1.bcb7b146a14b3p-4, 0x1.63c627d5219cbp-4, -0x1.2880736c8762dp-4, + 0x1.fc1ecf913961ap-5 + }; + uint32_t ux = asuint (x); + if (__glibc_unlikely (ux < (1 << 23) || ux >= 0x7f800000u)) + { + if (ux == 0 || ux >= 0x7f800000u) + return as_special (x); + /* subnormal */ + int n = __builtin_clz (ux) - 8; + ux <<= n; + ux -= n << 23; + } + unsigned m = ux & ((1 << 23) - 1), j = (m + (1 << (23 - 7))) >> (23 - 6); + double ix = tr[j], l = tl[j]; + int e = ((int) ux >> 23) - 127; + unsigned je = e + 1; + je = (je * 0x4d104d4) >> 28; + if (__glibc_unlikely (ux == st[je].u)) + return je; + + double tz = asdouble (((int64_t) m | ((int64_t) 1023 << 23)) << (52 - 23)); + double z = tz * ix - 1, z2 = z * z; + double r + = ((e * 0x1.34413509f79ffp-2 + l) + z * b[0]) + z2 * (b[1] + z * b[2]); + float ub = r, lb = r + 0x1.b008p-34; + if (__glibc_unlikely (ub != lb)) + { + double f = z + * ((c[0] + z * c[1]) + + z2 + * ((c[2] + z * c[3]) + + z2 * (c[4] + z * c[5] + z2 * c[6]))); + f -= 0x1.0cee0ed4ca7e9p-54 * e; + f += l - tl[0]; + double el = e * 0x1.34413509f7ap-2; + r = el + f; + ub = r; + tz = r; + if (__glibc_unlikely (!((asuint64 (tz) & ((1 << 28) - 1))))) + { + double dr = (el - r) + f; + r += dr * 32; + ub = r; } - if (__builtin_expect(hx >= 0x7f800000, 0)) return x+x; - k += (hx>>23)-127; - i = ((uint32_t)k&0x80000000)>>31; - hx = (hx&0x007fffff)|((0x7f-i)<<23); - y = (float)(k+i); - if (FIX_INT_FP_CONVERT_ZERO && y == 0.0f) - y = 0.0f; - SET_FLOAT_WORD(x,hx); - z = y*log10_2lo + ivln10*__ieee754_logf(x); - return z+y*log10_2hi; + } + return ub; } libm_alias_finite (__ieee754_log10f, __log10f) |