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-rw-r--r--ChangeLog12
-rw-r--r--NEWS2
-rw-r--r--math/Makefile3
-rw-r--r--sysdeps/i386/fpu/e_log2_data.c1
-rw-r--r--sysdeps/ia64/fpu/e_log2_data.c1
-rw-r--r--sysdeps/ieee754/dbl-64/e_log2.c240
-rw-r--r--sysdeps/ieee754/dbl-64/e_log2_data.c220
-rw-r--r--sysdeps/ieee754/dbl-64/math_config.h16
-rw-r--r--sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c128
-rw-r--r--sysdeps/m68k/m680x0/fpu/e_log2_data.c1
10 files changed, 378 insertions, 246 deletions
diff --git a/ChangeLog b/ChangeLog
index 8c990ad7b7..696e456957 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,17 @@
2018-09-12 Szabolcs Nagy <szabolcs.nagy@arm.com>
+ * NEWS: Mention log2 improvements.
+ * math/Makefile (type-double-routines): Add e_log2_data.
+ * sysdeps/i386/fpu/e_log2_data.c: New file.
+ * sysdeps/ia64/fpu/e_log2_data.c: New file.
+ * sysdeps/ieee754/dbl-64/e_log2.c: Rewrite.
+ * sysdeps/ieee754/dbl-64/e_log2_data.c: New file.
+ * sysdeps/ieee754/dbl-64/math_config.h (__log2_data): Add.
+ * sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c: Remove.
+ * sysdeps/m68k/m680x0/fpu/e_log2_data.c: New file.
+
+2018-09-12 Szabolcs Nagy <szabolcs.nagy@arm.com>
+
* NEWS: Mention log improvement.
* math/Makefile (type-double-routines): Add e_log_data.
* sysdeps/i386/fpu/e_log_data.c: New file.
diff --git a/NEWS b/NEWS
index 79bee8ee6b..04a0e89010 100644
--- a/NEWS
+++ b/NEWS
@@ -16,7 +16,7 @@ Major new features:
to set the install root if you wish to install into a non-default
configured location.
-* Optimized generic exp, exp2, log, sinf, cosf, sincosf and tanf.
+* Optimized generic exp, exp2, log, log2, sinf, cosf, sincosf and tanf.
* The reallocarray function is now declared under _DEFAULT_SOURCE, not just
for _GNU_SOURCE, to match BSD environments.
diff --git a/math/Makefile b/math/Makefile
index 8bfbebc4d0..2537b2a9ad 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -127,7 +127,8 @@ type-ldouble-yes := ldouble
type-double-suffix :=
type-double-routines := branred doasin dosincos mpa mpatan2 \
k_rem_pio2 mpatan mpsqrt mptan sincos32 \
- sincostab math_err e_exp_data e_log_data
+ sincostab math_err e_exp_data e_log_data \
+ e_log2_data
# float support
type-float-suffix := f
diff --git a/sysdeps/i386/fpu/e_log2_data.c b/sysdeps/i386/fpu/e_log2_data.c
new file mode 100644
index 0000000000..1cc8931700
--- /dev/null
+++ b/sysdeps/i386/fpu/e_log2_data.c
@@ -0,0 +1 @@
+/* Not needed. */
diff --git a/sysdeps/ia64/fpu/e_log2_data.c b/sysdeps/ia64/fpu/e_log2_data.c
new file mode 100644
index 0000000000..1cc8931700
--- /dev/null
+++ b/sysdeps/ia64/fpu/e_log2_data.c
@@ -0,0 +1 @@
+/* Not needed. */
diff --git a/sysdeps/ieee754/dbl-64/e_log2.c b/sysdeps/ieee754/dbl-64/e_log2.c
index e4a6aff9a3..916eb466f8 100644
--- a/sysdeps/ieee754/dbl-64/e_log2.c
+++ b/sysdeps/ieee754/dbl-64/e_log2.c
@@ -1,133 +1,141 @@
-/* Adapted for log2 by Ulrich Drepper <drepper@cygnus.com>. */
-/*
- * ====================================================
- * 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.
- * ====================================================
- */
+/* Double-precision log2(x) function.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
-/* __ieee754_log2(x)
- * Return the logarithm to base 2 of x
- *
- * Method :
- * 1. Argument Reduction: find k and f such that
- * x = 2^k * (1+f),
- * where sqrt(2)/2 < 1+f < sqrt(2) .
- *
- * 2. Approximation of log(1+f).
- * Let s = f/(2+f) ; based on log(1+f) = log(1+s) - log(1-s)
- * = 2s + 2/3 s**3 + 2/5 s**5 + .....,
- * = 2s + s*R
- * We use a special Reme algorithm on [0,0.1716] to generate
- * a polynomial of degree 14 to approximate R The maximum error
- * of this polynomial approximation is bounded by 2**-58.45. In
- * other words,
- * 2 4 6 8 10 12 14
- * R(z) ~ Lg1*s +Lg2*s +Lg3*s +Lg4*s +Lg5*s +Lg6*s +Lg7*s
- * (the values of Lg1 to Lg7 are listed in the program)
- * and
- * | 2 14 | -58.45
- * | Lg1*s +...+Lg7*s - R(z) | <= 2
- * | |
- * Note that 2s = f - s*f = f - hfsq + s*hfsq, where hfsq = f*f/2.
- * In order to guarantee error in log below 1ulp, we compute log
- * by
- * log(1+f) = f - s*(f - R) (if f is not too large)
- * log(1+f) = f - (hfsq - s*(hfsq+R)). (better accuracy)
- *
- * 3. Finally, log(x) = k + log(1+f).
- * = k+(f-(hfsq-(s*(hfsq+R))))
- *
- * Special cases:
- * log2(x) is NaN with signal if x < 0 (including -INF) ;
- * log2(+INF) is +INF; log(0) is -INF with signal;
- * log2(NaN) is that NaN with no signal.
- *
- * Constants:
- * The hexadecimal values are the intended ones for the following
- * constants. The decimal values may be used, provided that the
- * compiler will convert from decimal to binary accurately enough
- * to produce the hexadecimal values shown.
- */
+ 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 <fix-int-fp-convert-zero.h>
+#include <stdint.h>
+#include "math_config.h"
-static const double ln2 = 0.69314718055994530942;
-static const double two54 = 1.80143985094819840000e+16; /* 43500000 00000000 */
-static const double Lg1 = 6.666666666666735130e-01; /* 3FE55555 55555593 */
-static const double Lg2 = 3.999999999940941908e-01; /* 3FD99999 9997FA04 */
-static const double Lg3 = 2.857142874366239149e-01; /* 3FD24924 94229359 */
-static const double Lg4 = 2.222219843214978396e-01; /* 3FCC71C5 1D8E78AF */
-static const double Lg5 = 1.818357216161805012e-01; /* 3FC74664 96CB03DE */
-static const double Lg6 = 1.531383769920937332e-01; /* 3FC39A09 D078C69F */
-static const double Lg7 = 1.479819860511658591e-01; /* 3FC2F112 DF3E5244 */
+#define T __log2_data.tab
+#define T2 __log2_data.tab2
+#define B __log2_data.poly1
+#define A __log2_data.poly
+#define InvLn2hi __log2_data.invln2hi
+#define InvLn2lo __log2_data.invln2lo
+#define N (1 << LOG2_TABLE_BITS)
+#define OFF 0x3fe6000000000000
-static const double zero = 0.0;
+/* Top 16 bits of a double. */
+static inline uint32_t
+top16 (double x)
+{
+ return asuint64 (x) >> 48;
+}
double
__ieee754_log2 (double x)
{
- double hfsq, f, s, z, R, w, t1, t2, dk;
- int32_t k, hx, i, j;
- uint32_t lx;
+ /* double_t for better performance on targets with FLT_EVAL_METHOD==2. */
+ double_t z, r, r2, r4, y, invc, logc, kd, hi, lo, t1, t2, t3, p;
+ uint64_t ix, iz, tmp;
+ uint32_t top;
+ int k, i;
- EXTRACT_WORDS (hx, lx, x);
+ ix = asuint64 (x);
+ top = top16 (x);
- k = 0;
- if (hx < 0x00100000)
- { /* x < 2**-1022 */
- if (__glibc_unlikely (((hx & 0x7fffffff) | lx) == 0))
- return -two54 / fabs (x); /* log(+-0)=-inf */
- if (__glibc_unlikely (hx < 0))
- return (x - x) / (x - x); /* log(-#) = NaN */
- k -= 54;
- x *= two54; /* subnormal number, scale up x */
- GET_HIGH_WORD (hx, x);
- }
- if (__glibc_unlikely (hx >= 0x7ff00000))
- return x + x;
- k += (hx >> 20) - 1023;
- hx &= 0x000fffff;
- i = (hx + 0x95f64) & 0x100000;
- SET_HIGH_WORD (x, hx | (i ^ 0x3ff00000)); /* normalize x or x/2 */
- k += (i >> 20);
- dk = (double) k;
- f = x - 1.0;
- if ((0x000fffff & (2 + hx)) < 3)
- { /* |f| < 2**-20 */
- if (f == zero)
- {
- if (FIX_INT_FP_CONVERT_ZERO && dk == 0.0)
- dk = 0.0;
- return dk;
- }
- R = f * f * (0.5 - 0.33333333333333333 * f);
- return dk - (R - f) / ln2;
- }
- s = f / (2.0 + f);
- z = s * s;
- i = hx - 0x6147a;
- w = z * z;
- j = 0x6b851 - hx;
- t1 = w * (Lg2 + w * (Lg4 + w * Lg6));
- t2 = z * (Lg1 + w * (Lg3 + w * (Lg5 + w * Lg7)));
- i |= j;
- R = t2 + t1;
- if (i > 0)
+#define LO asuint64 (1.0 - 0x1.5b51p-5)
+#define HI asuint64 (1.0 + 0x1.6ab2p-5)
+ if (__glibc_unlikely (ix - LO < HI - LO))
{
- hfsq = 0.5 * f * f;
- return dk - ((hfsq - (s * (hfsq + R))) - f) / ln2;
+ /* Handle close to 1.0 inputs separately. */
+ /* Fix sign of zero with downward rounding when x==1. */
+ if (WANT_ROUNDING && __glibc_unlikely (ix == asuint64 (1.0)))
+ return 0;
+ r = x - 1.0;
+#ifdef __FP_FAST_FMA
+ hi = r * InvLn2hi;
+ lo = r * InvLn2lo + __builtin_fma (r, InvLn2hi, -hi);
+#else
+ double_t rhi, rlo;
+ rhi = asdouble (asuint64 (r) & -1ULL << 32);
+ rlo = r - rhi;
+ hi = rhi * InvLn2hi;
+ lo = rlo * InvLn2hi + r * InvLn2lo;
+#endif
+ r2 = r * r; /* rounding error: 0x1p-62. */
+ r4 = r2 * r2;
+ /* Worst-case error is less than 0.54 ULP (0.55 ULP without fma). */
+ p = r2 * (B[0] + r * B[1]);
+ y = hi + p;
+ lo += hi - y + p;
+ lo += r4 * (B[2] + r * B[3] + r2 * (B[4] + r * B[5])
+ + r4 * (B[6] + r * B[7] + r2 * (B[8] + r * B[9])));
+ y += lo;
+ return y;
}
- else
+ if (__glibc_unlikely (top - 0x0010 >= 0x7ff0 - 0x0010))
{
- return dk - ((s * (f - R)) - f) / ln2;
+ /* x < 0x1p-1022 or inf or nan. */
+ if (ix * 2 == 0)
+ return __math_divzero (1);
+ if (ix == asuint64 (INFINITY)) /* log(inf) == inf. */
+ return x;
+ if ((top & 0x8000) || (top & 0x7ff0) == 0x7ff0)
+ return __math_invalid (x);
+ /* x is subnormal, normalize it. */
+ ix = asuint64 (x * 0x1p52);
+ ix -= 52ULL << 52;
}
-}
+ /* 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 >> (52 - LOG2_TABLE_BITS)) % N;
+ k = (int64_t) tmp >> 52; /* arithmetic shift */
+ iz = ix - (tmp & 0xfffULL << 52);
+ invc = T[i].invc;
+ logc = T[i].logc;
+ z = asdouble (iz);
+ kd = (double_t) k;
+
+ /* log2(x) = log2(z/c) + log2(c) + k. */
+ /* r ~= z/c - 1, |r| < 1/(2*N). */
+#ifdef __FP_FAST_FMA
+ /* rounding error: 0x1p-55/N. */
+ r = __builtin_fma (z, invc, -1.0);
+ t1 = r * InvLn2hi;
+ t2 = r * InvLn2lo + __builtin_fma (r, InvLn2hi, -t1);
+#else
+ double_t rhi, rlo;
+ /* rounding error: 0x1p-55/N + 0x1p-65. */
+ r = (z - T2[i].chi - T2[i].clo) * invc;
+ rhi = asdouble (asuint64 (r) & -1ULL << 32);
+ rlo = r - rhi;
+ t1 = rhi * InvLn2hi;
+ t2 = rlo * InvLn2hi + r * InvLn2lo;
+#endif
+
+ /* hi + lo = r/ln2 + log2(c) + k. */
+ t3 = kd + logc;
+ hi = t3 + t1;
+ lo = t3 - hi + t1 + t2;
+
+ /* log2(r+1) = r/ln2 + r^2*poly(r). */
+ /* Evaluation is optimized assuming superscalar pipelined execution. */
+ r2 = r * r; /* rounding error: 0x1p-54/N^2. */
+ r4 = r2 * r2;
+ /* Worst-case error if |y| > 0x1p-4: 0.547 ULP (0.550 ULP without fma).
+ ~ 0.5 + 2/N/ln2 + abs-poly-error*0x1p56 ULP (+ 0.003 ULP without fma). */
+ p = A[0] + r * A[1] + r2 * (A[2] + r * A[3]) + r4 * (A[4] + r * A[5]);
+ y = lo + r2 * p + hi;
+ return y;
+}
+#ifndef __ieee754_log2
strong_alias (__ieee754_log2, __log2_finite)
+#endif
diff --git a/sysdeps/ieee754/dbl-64/e_log2_data.c b/sysdeps/ieee754/dbl-64/e_log2_data.c
new file mode 100644
index 0000000000..f650072421
--- /dev/null
+++ b/sysdeps/ieee754/dbl-64/e_log2_data.c
@@ -0,0 +1,220 @@
+/* Data for log2.
+ Copyright (C) 2018 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"
+
+#define N (1 << LOG2_TABLE_BITS)
+
+const struct log2_data __log2_data = {
+// First coefficient: 0x1.71547652b82fe1777d0ffda0d24p0
+.invln2hi = 0x1.7154765200000p+0,
+.invln2lo = 0x1.705fc2eefa200p-33,
+.poly1 = {
+#if LOG2_POLY1_ORDER == 11
+// relative error: 0x1.2fad8188p-63
+// in -0x1.5b51p-5 0x1.6ab2p-5
+-0x1.71547652b82fep-1,
+0x1.ec709dc3a03f7p-2,
+-0x1.71547652b7c3fp-2,
+0x1.2776c50f05be4p-2,
+-0x1.ec709dd768fe5p-3,
+0x1.a61761ec4e736p-3,
+-0x1.7153fbc64a79bp-3,
+0x1.484d154f01b4ap-3,
+-0x1.289e4a72c383cp-3,
+0x1.0b32f285aee66p-3,
+#endif
+},
+.poly = {
+#if N == 64 && LOG2_POLY_ORDER == 7
+// relative error: 0x1.a72c2bf8p-58
+// abs error: 0x1.67a552c8p-66
+// in -0x1.f45p-8 0x1.f45p-8
+-0x1.71547652b8339p-1,
+0x1.ec709dc3a04bep-2,
+-0x1.7154764702ffbp-2,
+0x1.2776c50034c48p-2,
+-0x1.ec7b328ea92bcp-3,
+0x1.a6225e117f92ep-3,
+#endif
+},
+/* Algorithm:
+
+ x = 2^k z
+ log2(x) = k + log2(c) + log2(z/c)
+ log2(z/c) = poly(z/c - 1)
+
+where z is in [1.6p-1; 1.6p0] which is split into N subintervals and z falls
+into the ith one, then table entries are computed as
+
+ tab[i].invc = 1/c
+ tab[i].logc = (double)log2(c)
+ tab2[i].chi = (double)c
+ tab2[i].clo = (double)(c - (double)c)
+
+where c is near the center of the subinterval and is chosen by trying +-2^29
+floating point invc candidates around 1/center and selecting one for which
+
+ 1) the rounding error in 0x1.8p10 + logc is 0,
+ 2) the rounding error in z - chi - clo is < 0x1p-64 and
+ 3) the rounding error in (double)log2(c) is minimized (< 0x1p-68).
+
+Note: 1) ensures that k + logc can be computed without rounding error, 2)
+ensures that z/c - 1 can be computed as (z - chi - clo)*invc with close to a
+single rounding error when there is no fast fma for z*invc - 1, 3) ensures
+that logc + poly(z/c - 1) has small error, however near x == 1 when
+|log2(x)| < 0x1p-4, this is not enough so that is special cased. */
+.tab = {
+#if N == 64
+{0x1.724286bb1acf8p+0, -0x1.1095feecdb000p-1},
+{0x1.6e1f766d2cca1p+0, -0x1.08494bd76d000p-1},
+{0x1.6a13d0e30d48ap+0, -0x1.00143aee8f800p-1},
+{0x1.661ec32d06c85p+0, -0x1.efec5360b4000p-2},
+{0x1.623fa951198f8p+0, -0x1.dfdd91ab7e000p-2},
+{0x1.5e75ba4cf026cp+0, -0x1.cffae0cc79000p-2},
+{0x1.5ac055a214fb8p+0, -0x1.c043811fda000p-2},
+{0x1.571ed0f166e1ep+0, -0x1.b0b67323ae000p-2},
+{0x1.53909590bf835p+0, -0x1.a152f5a2db000p-2},
+{0x1.5014fed61adddp+0, -0x1.9217f5af86000p-2},
+{0x1.4cab88e487bd0p+0, -0x1.8304db0719000p-2},
+{0x1.49539b4334feep+0, -0x1.74189f9a9e000p-2},
+{0x1.460cbdfafd569p+0, -0x1.6552bb5199000p-2},
+{0x1.42d664ee4b953p+0, -0x1.56b23a29b1000p-2},
+{0x1.3fb01111dd8a6p+0, -0x1.483650f5fa000p-2},
+{0x1.3c995b70c5836p+0, -0x1.39de937f6a000p-2},
+{0x1.3991c4ab6fd4ap+0, -0x1.2baa1538d6000p-2},
+{0x1.3698e0ce099b5p+0, -0x1.1d98340ca4000p-2},
+{0x1.33ae48213e7b2p+0, -0x1.0fa853a40e000p-2},
+{0x1.30d191985bdb1p+0, -0x1.01d9c32e73000p-2},
+{0x1.2e025cab271d7p+0, -0x1.e857da2fa6000p-3},
+{0x1.2b404cf13cd82p+0, -0x1.cd3c8633d8000p-3},
+{0x1.288b02c7ccb50p+0, -0x1.b26034c14a000p-3},
+{0x1.25e2263944de5p+0, -0x1.97c1c2f4fe000p-3},
+{0x1.234563d8615b1p+0, -0x1.7d6023f800000p-3},
+{0x1.20b46e33eaf38p+0, -0x1.633a71a05e000p-3},
+{0x1.1e2eefdcda3ddp+0, -0x1.494f5e9570000p-3},
+{0x1.1bb4a580b3930p+0, -0x1.2f9e424e0a000p-3},
+{0x1.19453847f2200p+0, -0x1.162595afdc000p-3},
+{0x1.16e06c0d5d73cp+0, -0x1.f9c9a75bd8000p-4},
+{0x1.1485f47b7e4c2p+0, -0x1.c7b575bf9c000p-4},
+{0x1.12358ad0085d1p+0, -0x1.960c60ff48000p-4},
+{0x1.0fef00f532227p+0, -0x1.64ce247b60000p-4},
+{0x1.0db2077d03a8fp+0, -0x1.33f78b2014000p-4},
+{0x1.0b7e6d65980d9p+0, -0x1.0387d1a42c000p-4},
+{0x1.0953efe7b408dp+0, -0x1.a6f9208b50000p-5},
+{0x1.07325cac53b83p+0, -0x1.47a954f770000p-5},
+{0x1.05197e40d1b5cp+0, -0x1.d23a8c50c0000p-6},
+{0x1.03091c1208ea2p+0, -0x1.16a2629780000p-6},
+{0x1.0101025b37e21p+0, -0x1.720f8d8e80000p-8},
+{0x1.fc07ef9caa76bp-1, 0x1.6fe53b1500000p-7},
+{0x1.f4465d3f6f184p-1, 0x1.11ccce10f8000p-5},
+{0x1.ecc079f84107fp-1, 0x1.c4dfc8c8b8000p-5},
+{0x1.e573a99975ae8p-1, 0x1.3aa321e574000p-4},
+{0x1.de5d6f0bd3de6p-1, 0x1.918a0d08b8000p-4},
+{0x1.d77b681ff38b3p-1, 0x1.e72e9da044000p-4},
+{0x1.d0cb5724de943p-1, 0x1.1dcd2507f6000p-3},
+{0x1.ca4b2dc0e7563p-1, 0x1.476ab03dea000p-3},
+{0x1.c3f8ee8d6cb51p-1, 0x1.7074377e22000p-3},
+{0x1.bdd2b4f020c4cp-1, 0x1.98ede8ba94000p-3},
+{0x1.b7d6c006015cap-1, 0x1.c0db86ad2e000p-3},
+{0x1.b20366e2e338fp-1, 0x1.e840aafcee000p-3},
+{0x1.ac57026295039p-1, 0x1.0790ab4678000p-2},
+{0x1.a6d01bc2731ddp-1, 0x1.1ac056801c000p-2},
+{0x1.a16d3bc3ff18bp-1, 0x1.2db11d4fee000p-2},
+{0x1.9c2d14967feadp-1, 0x1.406464ec58000p-2},
+{0x1.970e4f47c9902p-1, 0x1.52dbe093af000p-2},
+{0x1.920fb3982bcf2p-1, 0x1.651902050d000p-2},
+{0x1.8d30187f759f1p-1, 0x1.771d2cdeaf000p-2},
+{0x1.886e5ebb9f66dp-1, 0x1.88e9c857d9000p-2},
+{0x1.83c97b658b994p-1, 0x1.9a80155e16000p-2},
+{0x1.7f405ffc61022p-1, 0x1.abe186ed3d000p-2},
+{0x1.7ad22181415cap-1, 0x1.bd0f2aea0e000p-2},
+{0x1.767dcf99eff8cp-1, 0x1.ce0a43dbf4000p-2},
+#endif
+},
+#ifndef __FP_FAST_FMA
+.tab2 = {
+# if N == 64
+{0x1.6200012b90a8ep-1, 0x1.904ab0644b605p-55},
+{0x1.66000045734a6p-1, 0x1.1ff9bea62f7a9p-57},
+{0x1.69fffc325f2c5p-1, 0x1.27ecfcb3c90bap-55},
+{0x1.6e00038b95a04p-1, 0x1.8ff8856739326p-55},
+{0x1.71fffe09994e3p-1, 0x1.afd40275f82b1p-55},
+{0x1.7600015590e1p-1, -0x1.2fd75b4238341p-56},
+{0x1.7a00012655bd5p-1, 0x1.808e67c242b76p-56},
+{0x1.7e0003259e9a6p-1, -0x1.208e426f622b7p-57},
+{0x1.81fffedb4b2d2p-1, -0x1.402461ea5c92fp-55},
+{0x1.860002dfafcc3p-1, 0x1.df7f4a2f29a1fp-57},
+{0x1.89ffff78c6b5p-1, -0x1.e0453094995fdp-55},
+{0x1.8e00039671566p-1, -0x1.a04f3bec77b45p-55},
+{0x1.91fffe2bf1745p-1, -0x1.7fa34400e203cp-56},
+{0x1.95fffcc5c9fd1p-1, -0x1.6ff8005a0695dp-56},
+{0x1.9a0003bba4767p-1, 0x1.0f8c4c4ec7e03p-56},
+{0x1.9dfffe7b92da5p-1, 0x1.e7fd9478c4602p-55},
+{0x1.a1fffd72efdafp-1, -0x1.a0c554dcdae7ep-57},
+{0x1.a5fffde04ff95p-1, 0x1.67da98ce9b26bp-55},
+{0x1.a9fffca5e8d2bp-1, -0x1.284c9b54c13dep-55},
+{0x1.adfffddad03eap-1, 0x1.812c8ea602e3cp-58},
+{0x1.b1ffff10d3d4dp-1, -0x1.efaddad27789cp-55},
+{0x1.b5fffce21165ap-1, 0x1.3cb1719c61237p-58},
+{0x1.b9fffd950e674p-1, 0x1.3f7d94194cep-56},
+{0x1.be000139ca8afp-1, 0x1.50ac4215d9bcp-56},
+{0x1.c20005b46df99p-1, 0x1.beea653e9c1c9p-57},
+{0x1.c600040b9f7aep-1, -0x1.c079f274a70d6p-56},
+{0x1.ca0006255fd8ap-1, -0x1.a0b4076e84c1fp-56},
+{0x1.cdfffd94c095dp-1, 0x1.8f933f99ab5d7p-55},
+{0x1.d1ffff975d6cfp-1, -0x1.82c08665fe1bep-58},
+{0x1.d5fffa2561c93p-1, -0x1.b04289bd295f3p-56},
+{0x1.d9fff9d228b0cp-1, 0x1.70251340fa236p-55},
+{0x1.de00065bc7e16p-1, -0x1.5011e16a4d80cp-56},
+{0x1.e200002f64791p-1, 0x1.9802f09ef62ep-55},
+{0x1.e600057d7a6d8p-1, -0x1.e0b75580cf7fap-56},
+{0x1.ea00027edc00cp-1, -0x1.c848309459811p-55},
+{0x1.ee0006cf5cb7cp-1, -0x1.f8027951576f4p-55},
+{0x1.f2000782b7dccp-1, -0x1.f81d97274538fp-55},
+{0x1.f6000260c450ap-1, -0x1.071002727ffdcp-59},
+{0x1.f9fffe88cd533p-1, -0x1.81bdce1fda8bp-58},
+{0x1.fdfffd50f8689p-1, 0x1.7f91acb918e6ep-55},
+{0x1.0200004292367p+0, 0x1.b7ff365324681p-54},
+{0x1.05fffe3e3d668p+0, 0x1.6fa08ddae957bp-55},
+{0x1.0a0000a85a757p+0, -0x1.7e2de80d3fb91p-58},
+{0x1.0e0001a5f3fccp+0, -0x1.1823305c5f014p-54},
+{0x1.11ffff8afbaf5p+0, -0x1.bfabb6680bac2p-55},
+{0x1.15fffe54d91adp+0, -0x1.d7f121737e7efp-54},
+{0x1.1a00011ac36e1p+0, 0x1.c000a0516f5ffp-54},
+{0x1.1e00019c84248p+0, -0x1.082fbe4da5dap-54},
+{0x1.220000ffe5e6ep+0, -0x1.8fdd04c9cfb43p-55},
+{0x1.26000269fd891p+0, 0x1.cfe2a7994d182p-55},
+{0x1.2a00029a6e6dap+0, -0x1.00273715e8bc5p-56},
+{0x1.2dfffe0293e39p+0, 0x1.b7c39dab2a6f9p-54},
+{0x1.31ffff7dcf082p+0, 0x1.df1336edc5254p-56},
+{0x1.35ffff05a8b6p+0, -0x1.e03564ccd31ebp-54},
+{0x1.3a0002e0eaeccp+0, 0x1.5f0e74bd3a477p-56},
+{0x1.3e000043bb236p+0, 0x1.c7dcb149d8833p-54},
+{0x1.4200002d187ffp+0, 0x1.e08afcf2d3d28p-56},
+{0x1.460000d387cb1p+0, 0x1.20837856599a6p-55},
+{0x1.4a00004569f89p+0, -0x1.9fa5c904fbcd2p-55},
+{0x1.4e000043543f3p+0, -0x1.81125ed175329p-56},
+{0x1.51fffcc027f0fp+0, 0x1.883d8847754dcp-54},
+{0x1.55ffffd87b36fp+0, -0x1.709e731d02807p-55},
+{0x1.59ffff21df7bap+0, 0x1.7f79f68727b02p-55},
+{0x1.5dfffebfc3481p+0, -0x1.180902e30e93ep-54},
+# endif
+},
+#endif /* __FP_FAST_FMA */
+};
diff --git a/sysdeps/ieee754/dbl-64/math_config.h b/sysdeps/ieee754/dbl-64/math_config.h
index 2eb793d4c8..9c3ea1d436 100644
--- a/sysdeps/ieee754/dbl-64/math_config.h
+++ b/sysdeps/ieee754/dbl-64/math_config.h
@@ -149,4 +149,20 @@ extern const struct log_data
#endif
} __log_data attribute_hidden;
+#define LOG2_TABLE_BITS 6
+#define LOG2_POLY_ORDER 7
+#define LOG2_POLY1_ORDER 11
+extern const struct log2_data
+{
+ double invln2hi;
+ double invln2lo;
+ double poly[LOG2_POLY_ORDER - 1];
+ double poly1[LOG2_POLY1_ORDER - 1];
+ /* See e_log2_data.c for details. */
+ struct {double invc, logc;} tab[1 << LOG2_TABLE_BITS];
+#ifndef __FP_FAST_FMA
+ struct {double chi, clo;} tab2[1 << LOG2_TABLE_BITS];
+#endif
+} __log2_data attribute_hidden;
+
#endif
diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c b/sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c
deleted file mode 100644
index f08d5b337d..0000000000
--- a/sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c
+++ /dev/null
@@ -1,128 +0,0 @@
-/*
- * ====================================================
- * 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.
- * ====================================================
- */
-
-/* __ieee754_log2(x)
- * Return the logarithm to base 2 of x
- *
- * Method :
- * 1. Argument Reduction: find k and f such that
- * x = 2^k * (1+f),
- * where sqrt(2)/2 < 1+f < sqrt(2) .
- *
- * 2. Approximation of log(1+f).
- * Let s = f/(2+f) ; based on log(1+f) = log(1+s) - log(1-s)
- * = 2s + 2/3 s**3 + 2/5 s**5 + .....,
- * = 2s + s*R
- * We use a special Reme algorithm on [0,0.1716] to generate
- * a polynomial of degree 14 to approximate R The maximum error
- * of this polynomial approximation is bounded by 2**-58.45. In
- * other words,
- * 2 4 6 8 10 12 14
- * R(z) ~ Lg1*s +Lg2*s +Lg3*s +Lg4*s +Lg5*s +Lg6*s +Lg7*s
- * (the values of Lg1 to Lg7 are listed in the program)
- * and
- * | 2 14 | -58.45
- * | Lg1*s +...+Lg7*s - R(z) | <= 2
- * | |
- * Note that 2s = f - s*f = f - hfsq + s*hfsq, where hfsq = f*f/2.
- * In order to guarantee error in log below 1ulp, we compute log
- * by
- * log(1+f) = f - s*(f - R) (if f is not too large)
- * log(1+f) = f - (hfsq - s*(hfsq+R)). (better accuracy)
- *
- * 3. Finally, log(x) = k + log(1+f).
- * = k+(f-(hfsq-(s*(hfsq+R))))
- *
- * Special cases:
- * log2(x) is NaN with signal if x < 0 (including -INF) ;
- * log2(+INF) is +INF; log(0) is -INF with signal;
- * log2(NaN) is that NaN with no signal.
- *
- * Constants:
- * The hexadecimal values are the intended ones for the following
- * constants. The decimal values may be used, provided that the
- * compiler will convert from decimal to binary accurately enough
- * to produce the hexadecimal values shown.
- */
-
-#include <math.h>
-#include <math_private.h>
-
-static const double ln2 = 0.69314718055994530942;
-static const double two54 = 1.80143985094819840000e+16; /* 4350000000000000 */
-static const double Lg1 = 6.666666666666735130e-01; /* 3FE5555555555593 */
-static const double Lg2 = 3.999999999940941908e-01; /* 3FD999999997FA04 */
-static const double Lg3 = 2.857142874366239149e-01; /* 3FD2492494229359 */
-static const double Lg4 = 2.222219843214978396e-01; /* 3FCC71C51D8E78AF */
-static const double Lg5 = 1.818357216161805012e-01; /* 3FC7466496CB03DE */
-static const double Lg6 = 1.531383769920937332e-01; /* 3FC39A09D078C69F */
-static const double Lg7 = 1.479819860511658591e-01; /* 3FC2F112DF3E5244 */
-
-static const double zero = 0.0;
-
-double
-__ieee754_log2 (double x)
-{
- double hfsq, f, s, z, R, w, t1, t2, dk;
- int64_t hx, i, j;
- int32_t k;
-
- EXTRACT_WORDS64 (hx, x);
-
- k = 0;
- if (hx < INT64_C(0x0010000000000000))
- { /* x < 2**-1022 */
- if (__glibc_unlikely ((hx & UINT64_C(0x7fffffffffffffff)) == 0))
- return -two54 / fabs (x); /* log(+-0)=-inf */
- if (__glibc_unlikely (hx < 0))
- return (x - x) / (x - x); /* log(-#) = NaN */
- k -= 54;
- x *= two54; /* subnormal number, scale up x */
- EXTRACT_WORDS64 (hx, x);
- }
- if (__glibc_unlikely (hx >= UINT64_C(0x7ff0000000000000)))
- return x + x;
- k += (hx >> 52) - 1023;
- hx &= UINT64_C(0x000fffffffffffff);
- i = (hx + UINT64_C(0x95f6400000000)) & UINT64_C(0x10000000000000);
- /* normalize x or x/2 */
- INSERT_WORDS64 (x, hx | (i ^ UINT64_C(0x3ff0000000000000)));
- k += (i >> 52);
- dk = (double) k;
- f = x - 1.0;
- if ((UINT64_C(0x000fffffffffffff) & (2 + hx)) < 3)
- { /* |f| < 2**-20 */
- if (f == zero)
- return dk;
- R = f * f * (0.5 - 0.33333333333333333 * f);
- return dk - (R - f) / ln2;
- }
- s = f / (2.0 + f);
- z = s * s;
- i = hx - UINT64_C(0x6147a00000000);
- w = z * z;
- j = UINT64_C(0x6b85100000000) - hx;
- 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 = 0.5 * f * f;
- return dk - ((hfsq - (s * (hfsq + R))) - f) / ln2;
- }
- else
- {
- return dk - ((s * (f - R)) - f) / ln2;
- }
-}
-
-strong_alias (__ieee754_log2, __log2_finite)
diff --git a/sysdeps/m68k/m680x0/fpu/e_log2_data.c b/sysdeps/m68k/m680x0/fpu/e_log2_data.c
new file mode 100644
index 0000000000..1cc8931700
--- /dev/null
+++ b/sysdeps/m68k/m680x0/fpu/e_log2_data.c
@@ -0,0 +1 @@
+/* Not needed. */