1# ===========================================================================
2#        http://www.nongnu.org/autoconf-archive/ax_gcc_x86_cpuid.html
3# ===========================================================================
4#
5# SYNOPSIS
6#
7#   AX_GCC_X86_CPUID(OP)
8#
9# DESCRIPTION
10#
11#   On Pentium and later x86 processors, with gcc or a compiler that has a
12#   compatible syntax for inline assembly instructions, run a small program
13#   that executes the cpuid instruction with input OP. This can be used to
14#   detect the CPU type.
15#
16#   On output, the values of the eax, ebx, ecx, and edx registers are stored
17#   as hexadecimal strings as "eax:ebx:ecx:edx" in the cache variable
18#   ax_cv_gcc_x86_cpuid_OP.
19#
20#   If the cpuid instruction fails (because you are running a
21#   cross-compiler, or because you are not using gcc, or because you are on
22#   a processor that doesn't have this instruction), ax_cv_gcc_x86_cpuid_OP
23#   is set to the string "unknown".
24#
25#   This macro mainly exists to be used in AX_GCC_ARCHFLAG.
26#
27# LICENSE
28#
29#   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
30#   Copyright (c) 2008 Matteo Frigo
31#
32#   This program is free software: you can redistribute it and/or modify it
33#   under the terms of the GNU General Public License as published by the
34#   Free Software Foundation, either version 3 of the License, or (at your
35#   option) any later version.
36#
37#   This program is distributed in the hope that it will be useful, but
38#   WITHOUT ANY WARRANTY; without even the implied warranty of
39#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
40#   Public License for more details.
41#
42#   You should have received a copy of the GNU General Public License along
43#   with this program. If not, see <http://www.gnu.org/licenses/>.
44#
45#   As a special exception, the respective Autoconf Macro's copyright owner
46#   gives unlimited permission to copy, distribute and modify the configure
47#   scripts that are the output of Autoconf when processing the Macro. You
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52#
53#   This special exception to the GPL applies to versions of the Autoconf
54#   Macro released by the Autoconf Archive. When you make and distribute a
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56#   exception to the GPL to apply to your modified version as well.
57
58AC_DEFUN([AX_GCC_X86_CPUID],
59[AC_REQUIRE([AC_PROG_CC])
60AC_LANG_PUSH([C])
61AC_CACHE_CHECK(for x86 cpuid $1 output, ax_cv_gcc_x86_cpuid_$1,
62 [AC_RUN_IFELSE([AC_LANG_PROGRAM([#include <stdio.h>], [
63     int op = $1, eax, ebx, ecx, edx;
64     FILE *f;
65      __asm__("cpuid"
66        : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
67        : "a" (op));
68     f = fopen("conftest_cpuid", "w"); if (!f) return 1;
69     fprintf(f, "%x:%x:%x:%x\n", eax, ebx, ecx, edx);
70     fclose(f);
71     return 0;
72])],
73     [ax_cv_gcc_x86_cpuid_$1=`cat conftest_cpuid`; rm -f conftest_cpuid],
74     [ax_cv_gcc_x86_cpuid_$1=unknown; rm -f conftest_cpuid],
75     [ax_cv_gcc_x86_cpuid_$1=unknown])])
76AC_LANG_POP([C])
77])
78