-/* 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)
projects / thirdparty / glibc.git / commitdiff
