2 dnl Copyright (C) 2007-2012 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], , ,
15 #error "isinf must be a macro, not a function"
18 if test "$ac_cv_have_decl_isinf" = yes; then
19 gl_CHECK_MATH_LIB([ISINF_LIBM], [x = isinf (x) + isinf ((float) x);])
20 if test "$ISINF_LIBM" != missing; then
21 dnl Test whether isinf() on 'long double' works.
23 case "$gl_cv_func_isinfl_works" in
25 *) ISINF_LIBM=missing;;
29 if test "$ac_cv_have_decl_isinf" != yes ||
30 test "$ISINF_LIBM" = missing; then
32 dnl No libraries are needed to link lib/isinf.c.
35 AC_SUBST([ISINF_LIBM])
38 dnl Test whether isinf() works:
39 dnl 1) Whether it correctly returns false for LDBL_MAX.
40 dnl 2) Whether on 'long double' recognizes all numbers which are neither
41 dnl finite nor infinite. This test fails on OpenBSD/x86, but could also
42 dnl fail e.g. on i686, x86_64, ia64, because of
43 dnl - pseudo-denormals on x86_64,
44 dnl - pseudo-zeroes, unnormalized numbers, and pseudo-denormals on i686,
45 dnl - pseudo-NaN, pseudo-Infinity, pseudo-zeroes, unnormalized numbers, and
46 dnl pseudo-denormals on ia64.
47 AC_DEFUN([gl_ISINFL_WORKS],
49 AC_REQUIRE([AC_PROG_CC])
50 AC_REQUIRE([gl_BIGENDIAN])
51 AC_REQUIRE([gl_LONG_DOUBLE_VS_DOUBLE])
52 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
53 AC_CACHE_CHECK([whether isinf(long double) works], [gl_cv_func_isinfl_works],
61 ((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
62 typedef union { unsigned int word[NWORDS]; long double value; }
64 /* On Irix 6.5, gcc 3.4.3 can't compute compile-time NaN, and needs the
65 runtime type conversion. */
67 static long double NaNl ()
73 # define NaNl() (0.0L / 0.0L)
86 /* The isinf macro should be immune against changes in the sign bit and
87 in the mantissa bits. The xor operation twiddles a bit that can only be
88 a sign bit or a mantissa bit (since the exponent never extends to
91 m.word[NWORDS / 2] ^= (unsigned int) 1 << (sizeof (unsigned int) * CHAR_BIT - 1);
92 for (i = 0; i < NWORDS; i++)
98 #if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
99 /* Representation of an 80-bit 'long double' as an initializer for a sequence
100 of 'unsigned int' words. */
101 # ifdef WORDS_BIGENDIAN
102 # define LDBL80_WORDS(exponent,manthi,mantlo) \
103 { ((unsigned int) (exponent) << 16) | ((unsigned int) (manthi) >> 16), \
104 ((unsigned int) (manthi) << 16) | (unsigned int) (mantlo) >> 16), \
105 (unsigned int) (mantlo) << 16 \
108 # define LDBL80_WORDS(exponent,manthi,mantlo) \
109 { mantlo, manthi, exponent }
112 static memory_long_double x =
113 { LDBL80_WORDS (0xFFFF, 0xC3333333, 0x00000000) };
118 /* Signalling NaN. */
119 static memory_long_double x =
120 { LDBL80_WORDS (0xFFFF, 0x83333333, 0x00000000) };
124 /* The isinf macro should recognize Pseudo-NaNs, Pseudo-Infinities,
125 Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals, as defined in
126 Intel IA-64 Architecture Software Developer's Manual, Volume 1:
127 Application Architecture.
128 Table 5-2 "Floating-Point Register Encodings"
129 Figure 5-6 "Memory to Floating-Point Register Data Translation"
132 static memory_long_double x =
133 { LDBL80_WORDS (0xFFFF, 0x40000001, 0x00000000) };
137 { /* Pseudo-Infinity. */
138 static memory_long_double x =
139 { LDBL80_WORDS (0xFFFF, 0x00000000, 0x00000000) };
144 static memory_long_double x =
145 { LDBL80_WORDS (0x4004, 0x00000000, 0x00000000) };
149 { /* Unnormalized number. */
150 static memory_long_double x =
151 { LDBL80_WORDS (0x4000, 0x63333333, 0x00000000) };
155 { /* Pseudo-Denormal. */
156 static memory_long_double x =
157 { LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) };
164 }]])], [gl_cv_func_isinfl_works=yes], [gl_cv_func_isinfl_works=no],
167 # Guess no on OpenBSD ia64, x86_64, i386.
168 ia64-*-openbsd* | x86_64-*-openbsd* | i*86-*-openbsd*)
169 gl_cv_func_isinfl_works="guessing no";;
171 gl_cv_func_isinfl_works="guessing yes";;