diff options
| author | Mans Rullgard <mans@mansr.com> | 2012-06-24 12:29:28 +0100 |
|---|---|---|
| committer | Michael Niedermayer <michaelni@gmx.at> | 2012-07-10 20:32:16 +0200 |
| commit | e346176de9809afec3724139ee320b613f753062 (patch) | |
| tree | bc26600a4bd00db28dc2100e80fc9228cfc5daa0 /libavutil/x86/cpu.c | |
| parent | 96890c001f32943a8d5823ae553d6022bee8850b (diff) | |
x86: cpu: clean up check for cpuid instruction support
This adds macros for accessing the EFLAGS register and uses
these instead of coding the entire check in inline asm.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Diffstat (limited to 'libavutil/x86/cpu.c')
| -rw-r--r-- | libavutil/x86/cpu.c | 36 |
1 files changed, 16 insertions, 20 deletions
diff --git a/libavutil/x86/cpu.c b/libavutil/x86/cpu.c index d77f0fcc15..663fb93e52 100644 --- a/libavutil/x86/cpu.c +++ b/libavutil/x86/cpu.c @@ -37,6 +37,16 @@ #define xgetbv(index, eax, edx) \ __asm__ (".byte 0x0f, 0x01, 0xd0" : "=a"(eax), "=d"(edx) : "c" (index)) +#define get_eflags(x) \ + __asm__ volatile ("pushfl \n" \ + "pop %0 \n" \ + : "=r"(x)) + +#define set_eflags(x) \ + __asm__ volatile ("push %0 \n" \ + "popfl \n" \ + :: "r"(x)) + /* Function to test if multimedia instructions are supported... */ int ff_get_cpu_flags_x86(void) { @@ -48,26 +58,12 @@ int ff_get_cpu_flags_x86(void) #if ARCH_X86_32 x86_reg a, c; - __asm__ volatile ( - /* See if CPUID instruction is supported ... */ - /* ... Get copies of EFLAGS into eax and ecx */ - "pushfl\n\t" - "pop %0\n\t" - "mov %0, %1\n\t" - - /* ... Toggle the ID bit in one copy and store */ - /* to the EFLAGS reg */ - "xor $0x200000, %0\n\t" - "push %0\n\t" - "popfl\n\t" - - /* ... Get the (hopefully modified) EFLAGS */ - "pushfl\n\t" - "pop %0\n\t" - : "=a" (a), "=c" (c) - : - : "cc" - ); + + /* Check if CPUID is supported by attempting to toggle the ID bit in + * the EFLAGS register. */ + get_eflags(a); + set_eflags(a ^ 0x200000); + get_eflags(c); if (a == c) return 0; /* CPUID not supported */ |