c.m4

autoconf是一个产生可以自动配置源代码包

# --------------
AC_DEFUN([AC_PROG_CC_C89],
[ AC_REQUIRE([AC_PROG_CC])dnl
  _AC_PROG_CC_C89
])


# AC_PROG_CC_C99
# --------------
AC_DEFUN([AC_PROG_CC_C99],
[ AC_REQUIRE([AC_PROG_CC])dnl
  _AC_PROG_CC_C99
])


# AC_PROG_CC_STDC
# ---------------
AC_DEFUN([AC_PROG_CC_STDC],
[ AC_REQUIRE([AC_PROG_CC])dnl
  AS_CASE([$ac_cv_prog_cc_stdc],
    [no], [ac_cv_prog_cc_c99=no; ac_cv_prog_cc_c89=no],
	  [_AC_PROG_CC_C99([ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c99],
	     [_AC_PROG_CC_C89([ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c89],
			      [ac_cv_prog_cc_stdc=no])])])dnl
  AC_MSG_CHECKING([for $CC option to accept ISO Standard C])
  AC_CACHE_VAL([ac_cv_prog_cc_stdc], [])
  AS_CASE([$ac_cv_prog_cc_stdc],
    [no], [AC_MSG_RESULT([unsupported])],
    [''], [AC_MSG_RESULT([none needed])],
          [AC_MSG_RESULT([$ac_cv_prog_cc_stdc])])
])


# AC_C_BACKSLASH_A
# ----------------
AC_DEFUN([AC_C_BACKSLASH_A],
[
  AC_CACHE_CHECK([whether backslash-a works in strings], ac_cv_c_backslash_a,
   [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],
     [[
#if '\a' == 'a'
      syntax error;
#endif
      char buf['\a' == 'a' ? -1 : 1];
      buf[0] = '\a';
      return buf[0] != "\a"[0];
     ]])],
     [ac_cv_c_backslash_a=yes],
     [ac_cv_c_backslash_a=no])])
  if test $ac_cv_c_backslash_a = yes; then
    AC_DEFINE(HAVE_C_BACKSLASH_A, 1,
      [Define if backslash-a works in C strings.])
  fi
])


# AC_C_CROSS
# ----------
# Has been merged into AC_PROG_CC.
AU_DEFUN([AC_C_CROSS], [])


# AC_C_CHAR_UNSIGNED
# ------------------
AC_DEFUN([AC_C_CHAR_UNSIGNED],
[AH_VERBATIM([__CHAR_UNSIGNED__],
[/* Define to 1 if type `char' is unsigned and you are not using gcc.  */
#ifndef __CHAR_UNSIGNED__
# undef __CHAR_UNSIGNED__
#endif])dnl
AC_CACHE_CHECK(whether char is unsigned, ac_cv_c_char_unsigned,
[AC_COMPILE_IFELSE([AC_LANG_BOOL_COMPILE_TRY([AC_INCLUDES_DEFAULT([])],
					     [((char) -1) < 0])],
		   ac_cv_c_char_unsigned=no, ac_cv_c_char_unsigned=yes)])
if test $ac_cv_c_char_unsigned = yes && test "$GCC" != yes; then
  AC_DEFINE(__CHAR_UNSIGNED__)
fi
])# AC_C_CHAR_UNSIGNED


# AC_C_BIGENDIAN ([ACTION-IF-TRUE], [ACTION-IF-FALSE], [ACTION-IF-UNKNOWN])
# -------------------------------------------------------------------------
AC_DEFUN([AC_C_BIGENDIAN],
[AC_CACHE_CHECK(whether byte ordering is bigendian, ac_cv_c_bigendian,
[# See if sys/param.h defines the BYTE_ORDER macro.
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <sys/types.h>
#include <sys/param.h>
],
[#if !BYTE_ORDER || !BIG_ENDIAN || !LITTLE_ENDIAN
 bogus endian macros
#endif
])],
[# It does; now see whether it defined to BIG_ENDIAN or not.
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <sys/types.h>
#include <sys/param.h>
], [#if BYTE_ORDER != BIG_ENDIAN
 not big endian
#endif
])], [ac_cv_c_bigendian=yes], [ac_cv_c_bigendian=no])],
[# It does not; compile a test program.
AC_RUN_IFELSE(
[AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT], [[
  /* Are we little or big endian?  From Harbison&Steele.  */
  union
  {
    long int l;
    char c[sizeof (long int)];
  } u;
  u.l = 1;
  return u.c[sizeof (long int) - 1] == 1;
]])],
	      [ac_cv_c_bigendian=no],
	      [ac_cv_c_bigendian=yes],
[# try to guess the endianness by grepping values into an object file
  ac_cv_c_bigendian=unknown
  AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
[[short int ascii_mm[] = { 0x4249, 0x4765, 0x6E44, 0x6961, 0x6E53, 0x7953, 0 };
short int ascii_ii[] = { 0x694C, 0x5454, 0x656C, 0x6E45, 0x6944, 0x6E61, 0 };
void _ascii () { char *s = (char *) ascii_mm; s = (char *) ascii_ii; }
short int ebcdic_ii[] = { 0x89D3, 0xE3E3, 0x8593, 0x95C5, 0x89C4, 0x9581, 0 };
short int ebcdic_mm[] = { 0xC2C9, 0xC785, 0x95C4, 0x8981, 0x95E2, 0xA8E2, 0 };
void _ebcdic () { char *s = (char *) ebcdic_mm; s = (char *) ebcdic_ii; }]],
[[ _ascii (); _ebcdic (); ]])],
[if grep BIGenDianSyS conftest.$ac_objext >/dev/null ; then
  ac_cv_c_bigendian=yes
fi
if grep LiTTleEnDian conftest.$ac_objext >/dev/null ; then
  if test "$ac_cv_c_bigendian" = unknown; then
    ac_cv_c_bigendian=no
  else
    # finding both strings is unlikely to happen, but who knows?
    ac_cv_c_bigendian=unknown
  fi
fi])])])])
case $ac_cv_c_bigendian in
  yes)
    m4_default([$1],
      [AC_DEFINE([WORDS_BIGENDIAN], 1,
	[Define to 1 if your processor stores words with the most significant
	 byte first (like Motorola and SPARC, unlike Intel and VAX).])]) ;;
  no)
    $2 ;;
  *)
    m4_default([$3],
      [AC_MSG_ERROR([unknown endianness
presetting ac_cv_c_bigendian=no (or yes) will help])]) ;;
esac
])# AC_C_BIGENDIAN


# AC_C_INLINE
# -----------
# Do nothing if the compiler accepts the inline keyword.
# Otherwise define inline to __inline__ or __inline if one of those work,
# otherwise define inline to be empty.
#
# HP C version B.11.11.04 doesn't allow a typedef as the return value for an
# inline function, only builtin types.
#
AN_IDENTIFIER([inline], [AC_C_INLINE])
AC_DEFUN([AC_C_INLINE],
[AC_CACHE_CHECK([for inline], ac_cv_c_inline,
[ac_cv_c_inline=no
for ac_kw in inline __inline__ __inline; do
  AC_COMPILE_IFELSE([AC_LANG_SOURCE(
[#ifndef __cplusplus
typedef int foo_t;
static $ac_kw foo_t static_foo () {return 0; }
$ac_kw foo_t foo () {return 0; }
#endif
])],
		    [ac_cv_c_inline=$ac_kw])
  test "$ac_cv_c_inline" != no && break
done
])
AH_VERBATIM([inline],
[/* Define to `__inline__' or `__inline' if that's what the C compiler
   calls it, or to nothing if 'inline' is not supported under any name.  */
#ifndef __cplusplus
#undef inline
#endif])
case $ac_cv_c_inline in
  inline | yes) ;;
  *)
    case $ac_cv_c_inline in
      no) ac_val=;;
      *) ac_val=$ac_cv_c_inline;;
    esac
    cat >>confdefs.h <<_ACEOF
#ifndef __cplusplus
#define inline $ac_val
#endif
_ACEOF
    ;;
esac
])# AC_C_INLINE


# AC_C_CONST
# ----------
AN_IDENTIFIER([const],  [AC_C_CONST])
AC_DEFUN([AC_C_CONST],
[AC_CACHE_CHECK([for an ANSI C-conforming const], ac_cv_c_const,
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],
[[/* FIXME: Include the comments suggested by Paul. */
#ifndef __cplusplus
  /* Ultrix mips cc rejects this.  */
  typedef int charset[2];
  const charset x;
  /* SunOS 4.1.1 cc rejects this.  */
  char const *const *ccp;
  char **p;
  /* NEC SVR4.0.2 mips cc rejects this.  */
  struct point {int x, y;};
  static struct point const zero = {0,0};
  /* AIX XL C 1.02.0.0 rejects this.
     It does not let you subtract one const X* pointer from another in
     an arm of an if-expression whose if-part is not a constant
     expression */
  const char *g = "string";
  ccp = &g + (g ? g-g : 0);
  /* HPUX 7.0 cc rejects these. */
  ++ccp;
  p = (char**) ccp;
  ccp = (char const *const *) p;
  { /* SCO 3.2v4 cc rejects this.  */
    char *t;
    char const *s = 0 ? (char *) 0 : (char const *) 0;

    *t++ = 0;
    if (s) return 0;
  }
  { /* Someone thinks the Sun supposedly-ANSI compiler will reject this.  */
    int x[] = {25, 17};
    const int *foo = &x[0];
    ++foo;
  }
  { /* Sun SC1.0 ANSI compiler rejects this -- but not the above. */
    typedef const int *iptr;
    iptr p = 0;
    ++p;
  }
  { /* AIX XL C 1.02.0.0 rejects this saying
       "k.c", line 2.27: 1506-025 (S) Operand must be a modifiable lvalue. */
    struct s { int j; const int *ap[3]; };
    struct s *b; b->j = 5;
  }
  { /* ULTRIX-32 V3.1 (Rev 9) vcc rejects this */
    const int foo = 10;
    if (!foo) return 0;
  }
  return !x[0] && !zero.x;
#endif
]])],
		   [ac_cv_c_const=yes],
		   [ac_cv_c_const=no])])
if test $ac_cv_c_const = no; then
  AC_DEFINE(const,,
	    [Define to empty if `const' does not conform to ANSI C.])
fi
])# AC_C_CONST


# AC_C_RESTRICT
# -------------
# based on acx_restrict.m4, from the GNU Autoconf Macro Archive at:
# http://autoconf-archive.cryp.to/acx_restrict.html
#
# Determine whether the C/C++ compiler supports the "restrict" keyword
# introduced in ANSI C99, or an equivalent.  Do nothing if the compiler
# accepts it.  Otherwise, if the compiler supports an equivalent,
# define "restrict" to be that.  Here are some variants:
# - GCC supports both __restrict and __restrict__
# - older DEC Alpha C compilers support only __restrict
# - _Restrict is the only spelling accepted by Sun WorkShop 6 update 2 C
# Otherwise, define "restrict" to be empty.
AN_IDENTIFIER([restrict], [AC_C_RESTRICT])
AC_DEFUN([AC_C_RESTRICT],
[AC_CACHE_CHECK([for C/C++ restrict keyword], ac_cv_c_restrict,
  [ac_cv_c_restrict=no
   # Try the official restrict keyword, then gcc's __restrict, and
   # the less common variants.
   for ac_kw in restrict __restrict __restrict__ _Restrict; do
     AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
      [[typedef int * int_ptr;
        int foo (int_ptr $ac_kw ip) {
        return ip[0];
       }]],
      [[int s[1];
        int * $ac_kw t = s;
        t[0] = 0;
        return foo(t)]])],
      [ac_cv_c_restrict=$ac_kw])
     test "$ac_cv_c_restrict" != no && break
   done
  ])
 case $ac_cv_c_restrict in
   restrict) ;;
   no) AC_DEFINE(restrict,,
	[Define to equivalent of C99 restrict keyword, or to nothing if this
	is not supported.  Do not define if restrict is supported directly.]) ;;
   *)  AC_DEFINE_UNQUOTED(restrict, $ac_cv_c_restrict) ;;
 esac
])# AC_C_RESTRICT


# AC_C_VOLATILE
# -------------
# Note that, unlike const, #defining volatile to be the empty string can
# actually turn a correct program into an incorrect one, since removing
# uses of volatile actually grants the compiler permission to perform
# optimizations that could break the user's code.  So, do not #define
# volatile away unless it is really necessary to allow the user's code
# to compile cleanly.  Benign compiler failures should be tolerated.
AN_IDENTIFIER([volatile], [AC_C_VOLATILE])
AC_DEFUN([AC_C_VOLATILE],
[AC_CACHE_CHECK([for working volatile], ac_cv_c_volatile,
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
volatile int x;
int * volatile y = (int *) 0;
return !x && !y;])],
		   [ac_cv_c_volatile=yes],
		   [ac_cv_c_volatile=no])])
if test $ac_cv_c_volatile = no; then
  AC_DEFINE(volatile,,
	    [Define to empty if the keyword `volatile' does not work.
	     Warning: valid code using `volatile' can become incorrect
	     without.  Disable with care.])
fi
])# AC_C_VOLATILE


# AC_C_STRINGIZE
# --------------
# Checks if `#' can be used to glue strings together at the CPP level.
# Defines HAVE_STRINGIZE if positive.
AC_DEFUN([AC_C_STRINGIZE],
[AC_CACHE_CHECK([for preprocessor stringizing operator],
		[ac_cv_c_stringize],
[AC_EGREP_CPP([@%:@teststring],
	      [@%:@define x(y) #y

char *s = x(teststring);],
	      [ac_cv_c_stringize=no],
	      [ac_cv_c_stringize=yes])])
if test $ac_cv_c_stringize = yes; then
  AC_DEFINE(HAVE_STRINGIZE, 1,
	    [Define to 1 if cpp supports the ANSI @%:@ stringizing operator.])
fi
])# AC_C_STRINGIZE


# AC_C_PROTOTYPES
# ---------------
# Check if the C compiler supports prototypes, included if it needs
# options.
AC_DEFUN([AC_C_PROTOTYPES],
[AC_REQUIRE([AC_PROG_CC])dnl
AC_MSG_CHECKING([for function prototypes])
if test "$ac_cv_prog_cc_c89" != no; then
  AC_MSG_RESULT([yes])
  AC_DEFINE(PROTOTYPES, 1,
	    [Define to 1 if the C compiler supports function prototypes.])
  AC_DEFINE(__PROTOTYPES, 1,
	    [Define like PROTOTYPES; this can be used by system headers.])
else
  AC_MSG_RESULT([no])
fi
])# AC_C_PROTOTYPES


# AC_C_TYPEOF
# -----------
# Check if the C compiler supports GCC's typeof syntax.
# The test case provokes incompatibilities in the Sun C compilers
# (both Solaris 8 and Solaris 10).
AC_DEFUN([AC_C_TYPEOF],
[
  AC_CACHE_CHECK([for typeof syntax and keyword spelling], ac_cv_c_typeof,
    [ac_cv_c_typeof=no
     for ac_kw in typeof __typeof__ no; do
       test $ac_kw = no && break
       AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],
	 [[
	   int value;
	   typedef struct {
		   char a [1
			   + ! (($ac_kw (value))
				(($ac_kw (value)) 0 < ($ac_kw (value)) -1
				 ? ($ac_kw (value)) - 1
				 : ~ (~ ($ac_kw (value)) 0
				      << sizeof ($ac_kw (value)))))]; }
	      ac__typeof_type_;
	   return
	     (! ((void) ((ac__typeof_type_ *) 0), 0));
	 ]])],
	 [ac_cv_c_typeof=$ac_kw])
       test $ac_cv_c_typeof != no && break
     done])
  if test $ac_cv_c_typeof != no; then
    AC_DEFINE([HAVE_TYPEOF], 1,
      [Define to 1 if typeof works with your compiler.])
    if test $ac_cv_c_typeof != typeof; then
      AC_DEFINE_UNQUOTED([typeof], [$ac_cv_c_typeof],
	[Define to __typeof__ if your compiler spells it that way.])
    fi
  fi
])