2 dnl Copyright (C) 2007-2011 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
9 AC_REQUIRE([gl_MATH_H_DEFAULTS])
10 dnl Persuade glibc <math.h> to declare isinf.
11 AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
12 AC_CHECK_DECLS([isinf], , , [[#include <math.h>]])
13 if test "$ac_cv_have_decl_isinf" = yes; then
14 gl_CHECK_MATH_LIB([ISINF_LIBM], [x = isinf (x) + isinf ((float) x);])
15 if test "$ISINF_LIBM" != missing; then
16 dnl Test whether isinf() on 'long double' works.
18 case "$gl_cv_func_isinfl_works" in
20 *) ISINF_LIBM=missing;;
24 if test "$ac_cv_have_decl_isinf" != yes ||
25 test "$ISINF_LIBM" = missing; then
27 dnl No libraries are needed to link lib/isinf.c.
30 AC_SUBST([ISINF_LIBM])
33 dnl Test whether isinf() works:
34 dnl 1) Whether it correctly returns false for LDBL_MAX.
35 dnl 2) Whether on 'long double' recognizes all numbers which are neither
36 dnl finite nor infinite. This test fails on OpenBSD/x86, but could also
37 dnl fail e.g. on i686, x86_64, ia64, because of
38 dnl - pseudo-denormals on x86_64,
39 dnl - pseudo-zeroes, unnormalized numbers, and pseudo-denormals on i686,
40 dnl - pseudo-NaN, pseudo-Infinity, pseudo-zeroes, unnormalized numbers, and
41 dnl pseudo-denormals on ia64.
42 AC_DEFUN([gl_ISINFL_WORKS],
44 AC_REQUIRE([AC_PROG_CC])
45 AC_REQUIRE([gl_BIGENDIAN])
46 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
47 AC_CACHE_CHECK([whether isinf(long double) works], [gl_cv_func_isinfl_works],
55 ((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
56 typedef union { unsigned int word[NWORDS]; long double value; }
58 /* On Irix 6.5, gcc 3.4.3 can't compute compile-time NaN, and needs the
59 runtime type conversion. */
61 static long double NaNl ()
67 # define NaNl() (0.0L / 0.0L)
80 /* The isinf macro should be immune against changes in the sign bit and
81 in the mantissa bits. The xor operation twiddles a bit that can only be
82 a sign bit or a mantissa bit (since the exponent never extends to
85 m.word[NWORDS / 2] ^= (unsigned int) 1 << (sizeof (unsigned int) * CHAR_BIT - 1);
86 for (i = 0; i < NWORDS; i++)
92 #if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_))
93 /* Representation of an 80-bit 'long double' as an initializer for a sequence
94 of 'unsigned int' words. */
95 # ifdef WORDS_BIGENDIAN
96 # define LDBL80_WORDS(exponent,manthi,mantlo) \
97 { ((unsigned int) (exponent) << 16) | ((unsigned int) (manthi) >> 16), \
98 ((unsigned int) (manthi) << 16) | (unsigned int) (mantlo) >> 16), \
99 (unsigned int) (mantlo) << 16 \
102 # define LDBL80_WORDS(exponent,manthi,mantlo) \
103 { mantlo, manthi, exponent }
106 static memory_long_double x =
107 { LDBL80_WORDS (0xFFFF, 0xC3333333, 0x00000000) };
112 /* Signalling NaN. */
113 static memory_long_double x =
114 { LDBL80_WORDS (0xFFFF, 0x83333333, 0x00000000) };
118 /* The isinf macro should recognize Pseudo-NaNs, Pseudo-Infinities,
119 Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals, as defined in
120 Intel IA-64 Architecture Software Developer's Manual, Volume 1:
121 Application Architecture.
122 Table 5-2 "Floating-Point Register Encodings"
123 Figure 5-6 "Memory to Floating-Point Register Data Translation"
126 static memory_long_double x =
127 { LDBL80_WORDS (0xFFFF, 0x40000001, 0x00000000) };
131 { /* Pseudo-Infinity. */
132 static memory_long_double x =
133 { LDBL80_WORDS (0xFFFF, 0x00000000, 0x00000000) };
138 static memory_long_double x =
139 { LDBL80_WORDS (0x4004, 0x00000000, 0x00000000) };
143 { /* Unnormalized number. */
144 static memory_long_double x =
145 { LDBL80_WORDS (0x4000, 0x63333333, 0x00000000) };
149 { /* Pseudo-Denormal. */
150 static memory_long_double x =
151 { LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) };
158 }]])], [gl_cv_func_isinfl_works=yes], [gl_cv_func_isinfl_works=no],
161 # Guess no on OpenBSD ia64, x86_64, i386.
162 ia64-*-openbsd* | x86_64-*-openbsd* | i*86-*-openbsd*)
163 gl_cv_func_isinfl_works="guessing no";;
165 gl_cv_func_isinfl_works="guessing yes";;