diff options
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/i386/fpu/e_logf_data.c | 1 | ||||
| -rw-r--r-- | sysdeps/ia64/fpu/e_logf_data.c | 1 | ||||
| -rw-r--r-- | sysdeps/ieee754/flt-32/e_logf.c | 148 | ||||
| -rw-r--r-- | sysdeps/ieee754/flt-32/e_logf_data.c | 44 | ||||
| -rw-r--r-- | sysdeps/ieee754/flt-32/math_config.h | 12 | ||||
| -rw-r--r-- | sysdeps/m68k/m680x0/fpu/e_logf_data.c | 1 |
6 files changed, 134 insertions, 73 deletions
diff --git a/sysdeps/i386/fpu/e_logf_data.c b/sysdeps/i386/fpu/e_logf_data.c new file mode 100644 index 0000000000..1cc8931700 --- /dev/null +++ b/sysdeps/i386/fpu/e_logf_data.c @@ -0,0 +1 @@ +/* Not needed. */ diff --git a/sysdeps/ia64/fpu/e_logf_data.c b/sysdeps/ia64/fpu/e_logf_data.c new file mode 100644 index 0000000000..1cc8931700 --- /dev/null +++ b/sysdeps/ia64/fpu/e_logf_data.c @@ -0,0 +1 @@ +/* Not needed. */ diff --git a/sysdeps/ieee754/flt-32/e_logf.c b/sysdeps/ieee754/flt-32/e_logf.c index cf75e11781..b8d262441f 100644 --- a/sysdeps/ieee754/flt-32/e_logf.c +++ b/sysdeps/ieee754/flt-32/e_logf.c @@ -1,85 +1,87 @@ -/* e_logf.c -- float version of e_log.c. - * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. - */ +/* Single-precision log function. + Copyright (C) 2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. -/* - * ==================================================== - * 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. - * ==================================================== - */ + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ #include <math.h> -#include <math_private.h> +#include <stdint.h> +#include "math_config.h" -static const float -ln2_hi = 6.9313812256e-01, /* 0x3f317180 */ -ln2_lo = 9.0580006145e-06, /* 0x3717f7d1 */ -two25 = 3.355443200e+07, /* 0x4c000000 */ -Lg1 = 6.6666668653e-01, /* 3F2AAAAB */ -Lg2 = 4.0000000596e-01, /* 3ECCCCCD */ -Lg3 = 2.8571429849e-01, /* 3E924925 */ -Lg4 = 2.2222198546e-01, /* 3E638E29 */ -Lg5 = 1.8183572590e-01, /* 3E3A3325 */ -Lg6 = 1.5313838422e-01, /* 3E1CD04F */ -Lg7 = 1.4798198640e-01; /* 3E178897 */ +/* +LOGF_TABLE_BITS = 4 +LOGF_POLY_ORDER = 4 -static const float zero = 0.0; +ULP error: 0.818 (nearest rounding.) +Relative error: 1.957 * 2^-26 (before rounding.) +*/ + +#define T __logf_data.tab +#define A __logf_data.poly +#define Ln2 __logf_data.ln2 +#define N (1 << LOGF_TABLE_BITS) +#define OFF 0x3f330000 float -__ieee754_logf(float x) +__ieee754_logf (float x) { - float hfsq,f,s,z,R,w,t1,t2,dk; - int32_t k,ix,i,j; + /* double_t for better performance on targets with FLT_EVAL_METHOD==2. */ + double_t z, r, r2, y, y0, invc, logc; + uint32_t ix, iz, tmp; + int k, i; + + ix = asuint (x); +#if WANT_ROUNDING + /* Fix sign of zero with downward rounding when x==1. */ + if (__glibc_unlikely (ix == 0x3f800000)) + return 0; +#endif + if (__glibc_unlikely (ix - 0x00800000 >= 0x7f800000 - 0x00800000)) + { + /* x < 0x1p-126 or inf or nan. */ + if (ix * 2 == 0) + return __math_divzerof (1); + if (ix == 0x7f800000) /* log(inf) == inf. */ + return x; + if ((ix & 0x80000000) || ix * 2 >= 0xff000000) + return __math_invalidf (x); + /* x is subnormal, normalize it. */ + ix = asuint (x * 0x1p23f); + ix -= 23 << 23; + } + + /* x = 2^k z; where z is in range [OFF,2*OFF] and exact. + The range is split into N subintervals. + The ith subinterval contains z and c is near its center. */ + tmp = ix - OFF; + i = (tmp >> (23 - LOGF_TABLE_BITS)) % N; + k = (int32_t) tmp >> 23; /* arithmetic shift */ + iz = ix - (tmp & 0x1ff << 23); + invc = T[i].invc; + logc = T[i].logc; + z = (double_t) asfloat (iz); - GET_FLOAT_WORD(ix,x); + /* log(x) = log1p(z/c-1) + log(c) + k*Ln2 */ + r = z * invc - 1; + y0 = logc + (double_t) k * Ln2; - k=0; - if (ix < 0x00800000) { /* x < 2**-126 */ - if (__builtin_expect((ix&0x7fffffff)==0, 0)) - return -two25/zero; /* log(+-0)=-inf */ - if (__builtin_expect(ix<0, 0)) - return (x-x)/(x-x); /* log(-#) = NaN */ - k -= 25; x *= two25; /* subnormal number, scale up x */ - GET_FLOAT_WORD(ix,x); - } - if (__builtin_expect(ix >= 0x7f800000, 0)) return x+x; - k += (ix>>23)-127; - ix &= 0x007fffff; - i = (ix+(0x95f64<<3))&0x800000; - SET_FLOAT_WORD(x,ix|(i^0x3f800000)); /* normalize x or x/2 */ - k += (i>>23); - f = x-(float)1.0; - if((0x007fffff&(15+ix))<16) { /* |f| < 2**-20 */ - if(f==zero) { - if(k==0) return zero; else {dk=(float)k; - return dk*ln2_hi+dk*ln2_lo;} - } - R = f*f*((float)0.5-(float)0.33333333333333333*f); - if(k==0) return f-R; else {dk=(float)k; - return dk*ln2_hi-((R-dk*ln2_lo)-f);} - } - s = f/((float)2.0+f); - dk = (float)k; - z = s*s; - i = ix-(0x6147a<<3); - w = z*z; - j = (0x6b851<<3)-ix; - t1= w*(Lg2+w*(Lg4+w*Lg6)); - t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7))); - i |= j; - R = t2+t1; - if(i>0) { - hfsq=(float)0.5*f*f; - if(k==0) return f-(hfsq-s*(hfsq+R)); else - return dk*ln2_hi-((hfsq-(s*(hfsq+R)+dk*ln2_lo))-f); - } else { - if(k==0) return f-s*(f-R); else - return dk*ln2_hi-((s*(f-R)-dk*ln2_lo)-f); - } + /* Pipelined polynomial evaluation to approximate log1p(r). */ + r2 = r * r; + y = A[1] * r + A[2]; + y = A[0] * r2 + y; + y = y * r2 + (y0 + r); + return (float) y; } strong_alias (__ieee754_logf, __logf_finite) diff --git a/sysdeps/ieee754/flt-32/e_logf_data.c b/sysdeps/ieee754/flt-32/e_logf_data.c new file mode 100644 index 0000000000..ce2a0f8a5c --- /dev/null +++ b/sysdeps/ieee754/flt-32/e_logf_data.c @@ -0,0 +1,44 @@ +/* Data definition for logf. + Copyright (C) 2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include "math_config.h" + +const struct logf_data __logf_data = { + .tab = { + { 0x1.661ec79f8f3bep+0, -0x1.57bf7808caadep-2 }, + { 0x1.571ed4aaf883dp+0, -0x1.2bef0a7c06ddbp-2 }, + { 0x1.49539f0f010bp+0, -0x1.01eae7f513a67p-2 }, + { 0x1.3c995b0b80385p+0, -0x1.b31d8a68224e9p-3 }, + { 0x1.30d190c8864a5p+0, -0x1.6574f0ac07758p-3 }, + { 0x1.25e227b0b8eap+0, -0x1.1aa2bc79c81p-3 }, + { 0x1.1bb4a4a1a343fp+0, -0x1.a4e76ce8c0e5ep-4 }, + { 0x1.12358f08ae5bap+0, -0x1.1973c5a611cccp-4 }, + { 0x1.0953f419900a7p+0, -0x1.252f438e10c1ep-5 }, + { 0x1p+0, 0x0p+0 }, + { 0x1.e608cfd9a47acp-1, 0x1.aa5aa5df25984p-5 }, + { 0x1.ca4b31f026aap-1, 0x1.c5e53aa362eb4p-4 }, + { 0x1.b2036576afce6p-1, 0x1.526e57720db08p-3 }, + { 0x1.9c2d163a1aa2dp-1, 0x1.bc2860d22477p-3 }, + { 0x1.886e6037841edp-1, 0x1.1058bc8a07ee1p-2 }, + { 0x1.767dcf5534862p-1, 0x1.4043057b6ee09p-2 }, + }, + .ln2 = 0x1.62e42fefa39efp-1, + .poly = { + -0x1.00ea348b88334p-2, 0x1.5575b0be00b6ap-2, -0x1.ffffef20a4123p-2, + } +}; diff --git a/sysdeps/ieee754/flt-32/math_config.h b/sysdeps/ieee754/flt-32/math_config.h index 31f0470612..953a4bc583 100644 --- a/sysdeps/ieee754/flt-32/math_config.h +++ b/sysdeps/ieee754/flt-32/math_config.h @@ -111,4 +111,16 @@ extern const struct exp2f_data double poly_scaled[EXP2F_POLY_ORDER]; } __exp2f_data attribute_hidden; +#define LOGF_TABLE_BITS 4 +#define LOGF_POLY_ORDER 4 +extern const struct logf_data +{ + struct + { + double invc, logc; + } tab[1 << LOGF_TABLE_BITS]; + double ln2; + double poly[LOGF_POLY_ORDER - 1]; /* First order coefficient is 1. */ +} __logf_data attribute_hidden; + #endif diff --git a/sysdeps/m68k/m680x0/fpu/e_logf_data.c b/sysdeps/m68k/m680x0/fpu/e_logf_data.c new file mode 100644 index 0000000000..1cc8931700 --- /dev/null +++ b/sysdeps/m68k/m680x0/fpu/e_logf_data.c @@ -0,0 +1 @@ +/* Not needed. */ |