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30891f35fa
We stopped adding "Contributed by" or similar lines in sources in 2012 in favour of git logs and keeping the Contributors section of the glibc manual up to date. Removing these lines makes the license header a bit more consistent across files and also removes the possibility of error in attribution when license blocks or files are copied across since the contributed-by lines don't actually reflect reality in those cases. Move all "Contributed by" and similar lines (Written by, Test by, etc.) into a new file CONTRIBUTED-BY to retain record of these contributions. These contributors are also mentioned in manual/contrib.texi, so we just maintain this additional record as a courtesy to the earlier developers. The following scripts were used to filter a list of files to edit in place and to clean up the CONTRIBUTED-BY file respectively. These were not added to the glibc sources because they're not expected to be of any use in future given that this is a one time task: https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
196 lines
5.0 KiB
C
196 lines
5.0 KiB
C
/* Copyright (C) 1997-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <stdio.h>
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#include <math.h>
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#include <gmp.h>
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#include <string.h>
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#include <limits.h>
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#include <assert.h>
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#define PRINT_ERRORS 0
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#define TOL 80
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#define N2 17
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#define FRAC (32*4)
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#define mpbpl (CHAR_BIT * sizeof (mp_limb_t))
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#define SZ (FRAC / mpbpl + 1)
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typedef mp_limb_t mp1[SZ], mp2[SZ * 2];
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/* This string has 101 hex digits. */
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static const char exp1[102] = "2" /* point */
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"b7e151628aed2a6abf7158809cf4f3c762e7160f38b4da56a7"
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"84d9045190cfef324e7738926cfbe5f4bf8d8d8c31d763da07";
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static const char hexdig[] = "0123456789abcdef";
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static void
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print_mpn_hex (const mp_limb_t *x, unsigned size)
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{
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char value[size + 1];
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unsigned i;
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const unsigned final = (size * 4 > SZ * mpbpl) ? SZ * mpbpl / 4 : size;
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memset (value, '0', size);
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for (i = 0; i < final ; i++)
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value[size - 1 - i] = hexdig[x[i * 4 / mpbpl] >> (i * 4) % mpbpl & 0xf];
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value[size] = '\0';
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fputs (value, stdout);
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}
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static void
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exp_mpn (mp1 ex, mp1 x)
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{
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unsigned n;
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mp1 xp;
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mp2 tmp;
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mp_limb_t chk __attribute__ ((unused));
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mp1 tol;
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memset (xp, 0, sizeof (mp1));
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memset (ex, 0, sizeof (mp1));
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xp[FRAC / mpbpl] = (mp_limb_t)1 << FRAC % mpbpl;
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memset (tol,0, sizeof (mp1));
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tol[(FRAC - TOL) / mpbpl] = (mp_limb_t)1 << (FRAC - TOL) % mpbpl;
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n = 0;
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do
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{
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/* Calculate sum(x^n/n!) until the next term is sufficiently small. */
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mpn_mul_n (tmp, xp, x, SZ);
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assert (tmp[SZ * 2 - 1] == 0);
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if (n > 0)
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mpn_divmod_1 (xp, tmp + FRAC / mpbpl, SZ, n);
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chk = mpn_add_n (ex, ex, xp, SZ);
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assert (chk == 0);
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n++;
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assert (n < 80); /* Catch too-high TOL. */
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}
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while (n < 10 || mpn_cmp (xp, tol, SZ) >= 0);
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}
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static int
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mpn_bitsize(const mp_limb_t *SRC_PTR, mp_size_t SIZE)
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{
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int i, j;
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for (i = SIZE - 1; i > 0; i--)
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if (SRC_PTR[i] != 0)
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break;
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for (j = mpbpl - 1; j >= 0; j--)
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if ((SRC_PTR[i] & (mp_limb_t)1 << j) != 0)
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break;
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return i * mpbpl + j;
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}
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static int
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do_test (void)
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{
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mp1 ex, x, xt, e2, e3;
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int i;
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int errors = 0;
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int failures = 0;
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mp1 maxerror;
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int maxerror_s = 0;
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const double sf = pow (2, mpbpl);
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/* assert (mpbpl == mp_bits_per_limb); */
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assert (FRAC / mpbpl * mpbpl == FRAC);
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memset (maxerror, 0, sizeof (mp1));
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memset (xt, 0, sizeof (mp1));
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xt[(FRAC - N2) / mpbpl] = (mp_limb_t)1 << (FRAC - N2) % mpbpl;
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for (i = 0; i < 1 << N2; i++)
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{
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int e2s, e3s, j;
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double de2;
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mpn_mul_1 (x,xt,SZ,i);
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exp_mpn (ex, x);
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de2 = exp (i / (double) (1 << N2));
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for (j = SZ-1; j >= 0; j--)
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{
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e2[j] = (mp_limb_t) de2;
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de2 = (de2 - e2[j]) * sf;
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}
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if (mpn_cmp (ex,e2,SZ) >= 0)
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mpn_sub_n (e3,ex,e2,SZ);
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else
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mpn_sub_n (e3,e2,ex,SZ);
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e2s = mpn_bitsize (e2,SZ);
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e3s = mpn_bitsize (e3,SZ);
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if (e3s >= 0 && e2s - e3s < 54)
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{
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#if PRINT_ERRORS
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printf ("%06x ", i * (0x100000 / (1 << N2)));
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print_mpn_hex (ex, (FRAC / 4) + 1);
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fputs ("\n ",stdout);
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print_mpn_hex (e2, (FRAC / 4) + 1);
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printf ("\n %c ",
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e2s - e3s < 54 ? e2s - e3s == 53 ? 'e' : 'F' : 'P');
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print_mpn_hex (e3, (FRAC / 4) + 1);
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putchar ('\n');
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#endif
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errors += (e2s - e3s == 53);
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failures += (e2s - e3s < 53);
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}
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if (e3s >= maxerror_s
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&& mpn_cmp (e3, maxerror, SZ) > 0)
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{
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memcpy (maxerror, e3, sizeof (mp1));
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maxerror_s = e3s;
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}
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}
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/* Check exp_mpn against precomputed value of exp(1). */
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memset (x, '\0', sizeof (mp1));
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x[FRAC / mpbpl] = (mp_limb_t)1 << FRAC % mpbpl;
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exp_mpn (ex, x);
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memset (e2, '\0', sizeof (mp1));
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for (i = -1; i < 100 && i < FRAC / 4; i++)
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e2[(FRAC - i * 4 - 4) / mpbpl] |= ((mp_limb_t) (strchr (hexdig,
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exp1[i + 1])
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- hexdig)
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<< (FRAC - i * 4 - 4) % mpbpl);
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if (mpn_cmp (ex, e2, SZ) >= 0)
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mpn_sub_n (e3, ex, e2, SZ);
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else
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mpn_sub_n (e3, e2, ex, SZ);
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printf ("%d failures; %d errors; error rate %0.2f%%\n", failures, errors,
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errors * 100.0 / (double) (1 << N2));
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fputs ("maximum error: ", stdout);
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print_mpn_hex (maxerror, (FRAC / 4) + 1);
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fputs ("\nerror in exp(1): ", stdout);
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print_mpn_hex (e3, (FRAC / 4) + 1);
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putchar ('\n');
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return failures == 0 ? 0 : 1;
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}
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#define TIMEOUT 200
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#define TEST_FUNCTION do_test ()
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#include "../test-skeleton.c"
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