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Diffstat (limited to 'Build/source/libs/zziplib/zziplib-0.13.58/m4/ax_check_aligned_access_required.m4')
-rw-r--r-- | Build/source/libs/zziplib/zziplib-0.13.58/m4/ax_check_aligned_access_required.m4 | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/Build/source/libs/zziplib/zziplib-0.13.58/m4/ax_check_aligned_access_required.m4 b/Build/source/libs/zziplib/zziplib-0.13.58/m4/ax_check_aligned_access_required.m4 new file mode 100644 index 00000000000..513e6bfffad --- /dev/null +++ b/Build/source/libs/zziplib/zziplib-0.13.58/m4/ax_check_aligned_access_required.m4 @@ -0,0 +1,57 @@ +dnl /usr/share/aclocal/guidod-cvs/ax_check_aligned_access_required.m4 +dnl @synopsis AC_CHECK_ALIGNED_ACCESS_REQUIRED +dnl +dnl While the x86 CPUs allow access to memory objects to be unaligned +dnl it happens that most of the modern designs require objects to be +dnl aligned - or they will fail with a buserror. That mode is quite known +dnl by big-endian machines (sparc, etc) however the alpha cpu is little- +dnl endian. +dnl +dnl The following function will test for aligned access to be required and +dnl set a config.h define HAVE_ALIGNED_ACCESS_REQUIRED (name derived by +dnl standard usage). Structures loaded from a file (or mmapped to memory) +dnl should be accessed per-byte in that case to avoid segfault type errors. +dnl +dnl @category C +dnl @author Guido U. Draheim <guidod@gmx.de> +dnl @version 2009-05-22 +dnl @license GPLWithACException + +AC_DEFUN([AX_CHECK_ALIGNED_ACCESS_REQUIRED], +[AC_CACHE_CHECK([if pointers to integers require aligned access], + [ax_cv_have_aligned_access_required], +[if test "$cross_compiling" = "yes"; then + case "$host_cpu" in alpha*|arm*|bfin*|hp*|mips*|sh*|sparc*|ia64|nv1) + ax_cv_have_aligned_access_required="yes" + ;; esac +else + AC_TRY_RUN([ +#include <stdio.h> +#include <stdlib.h> + +int main() +{ + char* string = malloc(40); + int i; + for (i=0; i < 40; i++) string[[i]] = i; + { + void* s = string; + int* p = s+1; + int* q = s+2; + + if (*p == *q) { return 1; } + } + return 0; +} + ], + [ax_cv_have_aligned_access_required=yes], + [ax_cv_have_aligned_access_required=no], + [ax_cv_have_aligned_access_required=no]) + ]) +fi +if test "$ax_cv_have_aligned_access_required" = yes ; then + AC_DEFINE([HAVE_ALIGNED_ACCESS_REQUIRED], [1], + [Define if pointers to integers require aligned access]) +fi +]) + |