From 50633f8f4e8d629e65d96f83abd9f99ca2cad463 Mon Sep 17 00:00:00 2001 From: Lorry Tar Creator Date: Tue, 26 Apr 2016 20:55:49 +0000 Subject: gzip-1.8 --- m4/exponentf.m4 | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 m4/exponentf.m4 (limited to 'm4/exponentf.m4') diff --git a/m4/exponentf.m4 b/m4/exponentf.m4 new file mode 100644 index 0000000..d4298f2 --- /dev/null +++ b/m4/exponentf.m4 @@ -0,0 +1,92 @@ +# exponentf.m4 serial 2 +dnl Copyright (C) 2007-2008, 2010-2016 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. +AC_DEFUN([gl_FLOAT_EXPONENT_LOCATION], +[ + AC_CACHE_CHECK([where to find the exponent in a 'float'], + [gl_cv_cc_float_expbit0], + [ + AC_RUN_IFELSE( + [AC_LANG_SOURCE([[ +#include +#include +#include +#include +#define NWORDS \ + ((sizeof (float) + sizeof (unsigned int) - 1) / sizeof (unsigned int)) +typedef union { float value; unsigned int word[NWORDS]; } memory_float; +static unsigned int ored_words[NWORDS]; +static unsigned int anded_words[NWORDS]; +static void add_to_ored_words (float x) +{ + memory_float m; + size_t i; + /* Clear it first, in case + sizeof (float) < sizeof (memory_float). */ + memset (&m, 0, sizeof (memory_float)); + m.value = x; + for (i = 0; i < NWORDS; i++) + { + ored_words[i] |= m.word[i]; + anded_words[i] &= m.word[i]; + } +} +int main () +{ + size_t j; + FILE *fp = fopen ("conftest.out", "w"); + if (fp == NULL) + return 1; + for (j = 0; j < NWORDS; j++) + anded_words[j] = ~ (unsigned int) 0; + add_to_ored_words (0.25f); + add_to_ored_words (0.5f); + add_to_ored_words (1.0f); + add_to_ored_words (2.0f); + add_to_ored_words (4.0f); + /* Remove bits that are common (e.g. if representation of the first mantissa + bit is explicit). */ + for (j = 0; j < NWORDS; j++) + ored_words[j] &= ~anded_words[j]; + /* Now find the nonzero word. */ + for (j = 0; j < NWORDS; j++) + if (ored_words[j] != 0) + break; + if (j < NWORDS) + { + size_t i; + for (i = j + 1; i < NWORDS; i++) + if (ored_words[i] != 0) + { + fprintf (fp, "unknown"); + return (fclose (fp) != 0); + } + for (i = 0; ; i++) + if ((ored_words[j] >> i) & 1) + { + fprintf (fp, "word %d bit %d", (int) j, (int) i); + return (fclose (fp) != 0); + } + } + fprintf (fp, "unknown"); + return (fclose (fp) != 0); +} + ]])], + [gl_cv_cc_float_expbit0=`cat conftest.out`], + [gl_cv_cc_float_expbit0="unknown"], + [gl_cv_cc_float_expbit0="word 0 bit 23"]) + rm -f conftest.out + ]) + case "$gl_cv_cc_float_expbit0" in + word*bit*) + word=`echo "$gl_cv_cc_float_expbit0" | sed -e 's/word //' -e 's/ bit.*//'` + bit=`echo "$gl_cv_cc_float_expbit0" | sed -e 's/word.*bit //'` + AC_DEFINE_UNQUOTED([FLT_EXPBIT0_WORD], [$word], + [Define as the word index where to find the exponent of 'float'.]) + AC_DEFINE_UNQUOTED([FLT_EXPBIT0_BIT], [$bit], + [Define as the bit index in the word where to find bit 0 of the exponent of 'float'.]) + ;; + esac +]) -- cgit v1.2.1