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- # va_copy.m4 serial 1 (js-1.6.20070208)
- dnl ##
- dnl ## Check for C99 va_copy() implementation
- dnl ## (and provide fallback implementation if neccessary)
- dnl ##
- dnl ## configure.in:
- dnl ## AC_CHECK_VA_COPY
- dnl ## foo.c:
- dnl ## #include "config.h"
- dnl ## [...]
- dnl ## va_copy(d,s)
- dnl ##
- dnl ## This check is rather complex: first because we really have to
- dnl ## try various possible implementations in sequence and second, we
- dnl ## cannot define a macro in config.h with parameters directly.
- dnl ##
- dnl # test program for va_copy() implementation
- changequote(<<,>>)
- m4_define(__va_copy_test, <<[
- #include <stdlib.h>
- #include <stdarg.h>
- #include <string.h>
- #define DO_VA_COPY(d, s) $1
- void test(char *str, ...)
- {
- va_list ap, ap2;
- int i;
- va_start(ap, str);
- DO_VA_COPY(ap2, ap);
- for (i = 1; i <= 9; i++) {
- int k = (int)va_arg(ap, int);
- if (k != i)
- abort();
- }
- DO_VA_COPY(ap, ap2);
- for (i = 1; i <= 9; i++) {
- int k = (int)va_arg(ap, int);
- if (k != i)
- abort();
- }
- va_end(ap);
- }
- int main(int argc, char *argv[])
- {
- test("test", 1, 2, 3, 4, 5, 6, 7, 8, 9);
- exit(0);
- }
- ]>>)
- changequote([,])
- dnl # test driver for va_copy() implementation
- m4_define(__va_copy_check, [
- AH_VERBATIM($1,
- [/* Predefined possible va_copy() implementation (id: $1) */
- #define __VA_COPY_USE_$1(d, s) $2])
- if test ".$ac_cv_va_copy" = .; then
- AC_TRY_RUN(__va_copy_test($2), [ac_cv_va_copy="$1"])
- fi
- ])
- dnl # Autoconf check for va_copy() implementation checking
- AC_DEFUN([AC_CHECK_VA_COPY],[
- dnl # provide Autoconf display check message
- AC_MSG_CHECKING(for va_copy() function)
- dnl # check for various implementations in priorized sequence
- AC_CACHE_VAL(ac_cv_va_copy, [
- ac_cv_va_copy=""
- dnl # 1. check for standardized C99 macro
- __va_copy_check(C99, [va_copy((d), (s))])
- dnl # 2. check for alternative/deprecated GCC macro
- __va_copy_check(GCM, [VA_COPY((d), (s))])
- dnl # 3. check for internal GCC macro (high-level define)
- __va_copy_check(GCH, [__va_copy((d), (s))])
- dnl # 4. check for internal GCC macro (built-in function)
- __va_copy_check(GCB, [__builtin_va_copy((d), (s))])
- dnl # 5. check for assignment approach (assuming va_list is a struct)
- __va_copy_check(ASS, [do { (d) = (s); } while (0)])
- dnl # 6. check for assignment approach (assuming va_list is a pointer)
- __va_copy_check(ASP, [do { *(d) = *(s); } while (0)])
- dnl # 7. check for memory copying approach (assuming va_list is a struct)
- __va_copy_check(CPS, [memcpy((void *)&(d), (void *)&(s)), sizeof((s))])
- dnl # 8. check for memory copying approach (assuming va_list is a pointer)
- __va_copy_check(CPP, [memcpy((void *)(d), (void *)(s)), sizeof(*(s))])
- if test ".$ac_cv_va_copy" = .; then
- AC_ERROR([no working implementation found])
- fi
- ])
- dnl # optionally activate the fallback implementation
- if test ".$ac_cv_va_copy" = ".C99"; then
- AC_DEFINE(HAVE_VA_COPY, 1, [Define if va_copy() macro exists (and no fallback implementation is required)])
- fi
- dnl # declare which fallback implementation to actually use
- AC_DEFINE_UNQUOTED([__VA_COPY_USE], [__VA_COPY_USE_$ac_cv_va_copy],
- [Define to id of used va_copy() implementation])
- dnl # provide activation hook for fallback implementation
- AH_VERBATIM([__VA_COPY_ACTIVATION],
- [/* Optional va_copy() implementation activation */
- #ifndef HAVE_VA_COPY
- #define va_copy(d, s) __VA_COPY_USE(d, s)
- #endif
- ])
- dnl # provide Autoconf display result message
- if test ".$ac_cv_va_copy" = ".C99"; then
- AC_MSG_RESULT([yes])
- else
- AC_MSG_RESULT([no (using fallback implementation)])
- fi
- ])
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