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.
7 AC_DEFUN([gl_ISFINITE],
9 AC_REQUIRE([gl_MATH_H_DEFAULTS])
10 dnl Persuade glibc <math.h> to declare isfinite.
11 AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
12 AC_CHECK_DECLS([isfinite], , , [#include <math.h>])
13 if test "$ac_cv_have_decl_isfinite" = yes; then
14 gl_CHECK_MATH_LIB([ISFINITE_LIBM], [x = isfinite (x);])
15 if test "$ISFINITE_LIBM" != missing; then
16 dnl Test whether isfinite() on 'long double' works.
18 case "$gl_cv_func_isfinitel_works" in
20 *) ISFINITE_LIBM=missing;;
22 dnl Also, isfinite() on 'double' does not work on Linux/ia64 (because of
23 dnl signalling NaNs). But this does not have to be tested, since
24 dnl isfinite(long double) also does not work in this situation.
27 if test "$ac_cv_have_decl_isfinite" != yes ||
28 test "$ISFINITE_LIBM" = missing; then
30 dnl No libraries are needed to link lib/isfinite.c.
33 AC_SUBST([ISFINITE_LIBM])
36 dnl Test whether isfinite() on 'long double' recognizes all numbers which are
37 dnl neither finite nor infinite. This test fails e.g. on i686, x86_64, ia64,
39 dnl - pseudo-denormals on x86_64,
40 dnl - pseudo-zeroes, unnormalized numbers, and pseudo-denormals on i686,
41 dnl - pseudo-NaN, pseudo-Infinity, pseudo-zeroes, unnormalized numbers, and
42 dnl pseudo-denormals on ia64.
43 AC_DEFUN([gl_ISFINITEL_WORKS],
45 AC_REQUIRE([AC_PROG_CC])
46 AC_REQUIRE([gl_BIGENDIAN])
47 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
48 AC_CACHE_CHECK([whether isfinite(long double) works], [gl_cv_func_isfinitel_works],
50 AC_RUN_IFELSE([AC_LANG_SOURCE([[
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)
77 /* The isfinite macro should be immune against changes in the sign bit and
78 in the mantissa bits. The xor operation twiddles a bit that can only be
79 a sign bit or a mantissa bit (since the exponent never extends to
82 m.word[NWORDS / 2] ^= (unsigned int) 1 << (sizeof (unsigned int) * CHAR_BIT - 1);
83 for (i = 0; i < NWORDS; i++)
85 if (isfinite (m.value))
89 #if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_))
90 /* Representation of an 80-bit 'long double' as an initializer for a sequence
91 of 'unsigned int' words. */
92 # ifdef WORDS_BIGENDIAN
93 # define LDBL80_WORDS(exponent,manthi,mantlo) \
94 { ((unsigned int) (exponent) << 16) | ((unsigned int) (manthi) >> 16), \
95 ((unsigned int) (manthi) << 16) | (unsigned int) (mantlo) >> 16), \
96 (unsigned int) (mantlo) << 16 \
99 # define LDBL80_WORDS(exponent,manthi,mantlo) \
100 { mantlo, manthi, exponent }
103 static memory_long_double x =
104 { LDBL80_WORDS (0xFFFF, 0xC3333333, 0x00000000) };
105 if (isfinite (x.value))
109 /* Signalling NaN. */
110 static memory_long_double x =
111 { LDBL80_WORDS (0xFFFF, 0x83333333, 0x00000000) };
112 if (isfinite (x.value))
115 /* The isfinite macro should recognize Pseudo-NaNs, Pseudo-Infinities,
116 Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals, as defined in
117 Intel IA-64 Architecture Software Developer's Manual, Volume 1:
118 Application Architecture.
119 Table 5-2 "Floating-Point Register Encodings"
120 Figure 5-6 "Memory to Floating-Point Register Data Translation"
123 static memory_long_double x =
124 { LDBL80_WORDS (0xFFFF, 0x40000001, 0x00000000) };
125 if (isfinite (x.value))
128 { /* Pseudo-Infinity. */
129 static memory_long_double x =
130 { LDBL80_WORDS (0xFFFF, 0x00000000, 0x00000000) };
131 if (isfinite (x.value))
135 static memory_long_double x =
136 { LDBL80_WORDS (0x4004, 0x00000000, 0x00000000) };
137 if (isfinite (x.value))
140 { /* Unnormalized number. */
141 static memory_long_double x =
142 { LDBL80_WORDS (0x4000, 0x63333333, 0x00000000) };
143 if (isfinite (x.value))
146 { /* Pseudo-Denormal. */
147 static memory_long_double x =
148 { LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) };
149 if (isfinite (x.value))
155 }]])], [gl_cv_func_isfinitel_works=yes], [gl_cv_func_isfinitel_works=no],
157 # Guess no on ia64, x86_64, i386.
158 ia64 | x86_64 | i*86) gl_cv_func_isnanl_works="guessing no";;
159 *) gl_cv_func_isnanl_works="guessing yes";;