2 dnl Copyright (C) 2007-2008 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
33 AC_SUBST([REPLACE_ISFINITE])
34 AC_SUBST([ISFINITE_LIBM])
37 dnl Test whether isfinite() on 'long double' recognizes all numbers which are
38 dnl neither finite nor infinite. This test fails e.g. on i686, x86_64, ia64,
40 dnl - pseudo-denormals on x86_64,
41 dnl - pseudo-zeroes, unnormalized numbers, and pseudo-denormals on i686,
42 dnl - pseudo-NaN, pseudo-Infinity, pseudo-zeroes, unnormalized numbers, and
43 dnl pseudo-denormals on ia64.
44 AC_DEFUN([gl_ISFINITEL_WORKS],
46 AC_REQUIRE([AC_PROG_CC])
47 AC_REQUIRE([AC_C_BIGENDIAN])
48 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
49 AC_CACHE_CHECK([whether isfinite(long double) works], [gl_cv_func_isfinitel_works],
56 ((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
57 typedef union { unsigned int word[NWORDS]; long double value; }
64 /* The isfinite macro should be immune against changes in the sign bit and
65 in the mantissa bits. The xor operation twiddles a bit that can only be
66 a sign bit or a mantissa bit (since the exponent never extends to
68 m.value = 0.0L / 0.0L;
69 m.word[NWORDS / 2] ^= (unsigned int) 1 << (sizeof (unsigned int) * CHAR_BIT - 1);
70 for (i = 0; i < NWORDS; i++)
72 if (isfinite (m.value))
75 #if ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_))
76 /* Representation of an 80-bit 'long double' as an initializer for a sequence
77 of 'unsigned int' words. */
78 # ifdef WORDS_BIGENDIAN
79 # define LDBL80_WORDS(exponent,manthi,mantlo) \
80 { ((unsigned int) (exponent) << 16) | ((unsigned int) (manthi) >> 16), \
81 ((unsigned int) (manthi) << 16) | (unsigned int) (mantlo) >> 16), \
82 (unsigned int) (mantlo) << 16 \
85 # define LDBL80_WORDS(exponent,manthi,mantlo) \
86 { mantlo, manthi, exponent }
89 static memory_long_double x =
90 { LDBL80_WORDS (0xFFFF, 0xC3333333, 0x00000000) };
91 if (isfinite (x.value))
96 static memory_long_double x =
97 { LDBL80_WORDS (0xFFFF, 0x83333333, 0x00000000) };
98 if (isfinite (x.value))
101 /* The isfinite macro should recognize Pseudo-NaNs, Pseudo-Infinities,
102 Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals, as defined in
103 Intel IA-64 Architecture Software Developer's Manual, Volume 1:
104 Application Architecture.
105 Table 5-2 "Floating-Point Register Encodings"
106 Figure 5-6 "Memory to Floating-Point Register Data Translation"
109 static memory_long_double x =
110 { LDBL80_WORDS (0xFFFF, 0x40000001, 0x00000000) };
111 if (isfinite (x.value))
114 { /* Pseudo-Infinity. */
115 static memory_long_double x =
116 { LDBL80_WORDS (0xFFFF, 0x00000000, 0x00000000) };
117 if (isfinite (x.value))
121 static memory_long_double x =
122 { LDBL80_WORDS (0x4004, 0x00000000, 0x00000000) };
123 if (isfinite (x.value))
126 { /* Unnormalized number. */
127 static memory_long_double x =
128 { LDBL80_WORDS (0x4000, 0x63333333, 0x00000000) };
129 if (isfinite (x.value))
132 { /* Pseudo-Denormal. */
133 static memory_long_double x =
134 { LDBL80_WORDS (0x0000, 0x83333333, 0x00000000) };
135 if (isfinite (x.value))
141 }], [gl_cv_func_isfinitel_works=yes], [gl_cv_func_isfinitel_works=no],
143 # Guess no on ia64, x86_64, i386.
144 ia64 | x86_64 | i*86) gl_cv_func_isnanl_works="guessing no";;
145 *) gl_cv_func_isnanl_works="guessing yes";;