diff options
Diffstat (limited to 'src/libpng/pnggccrd.c')
| -rw-r--r-- | src/libpng/pnggccrd.c | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/src/libpng/pnggccrd.c b/src/libpng/pnggccrd.c new file mode 100644 index 0000000..a7248d6 --- /dev/null +++ b/src/libpng/pnggccrd.c @@ -0,0 +1,101 @@ +/* pnggccrd.c was removed from libpng-1.2.20. */ + +/* This code snippet is for use by configure's compilation test. */ + +#if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && \ + defined(PNG_MMX_CODE_SUPPORTED) +int PNGAPI png_dummy_mmx_support(void); + +static int _mmx_supported = 2; // 0: no MMX; 1: MMX supported; 2: not tested + +int PNGAPI +png_dummy_mmx_support(void) __attribute__((noinline)); + +int PNGAPI +png_dummy_mmx_support(void) +{ + int result; +#if defined(PNG_MMX_CODE_SUPPORTED) // superfluous, but what the heck + __asm__ __volatile__ ( +#if defined(__x86_64__) + "pushq %%rbx \n\t" // rbx gets clobbered by CPUID instruction + "pushq %%rcx \n\t" // so does rcx... + "pushq %%rdx \n\t" // ...and rdx (but rcx & rdx safe on Linux) + "pushfq \n\t" // save Eflag to stack + "popq %%rax \n\t" // get Eflag from stack into rax + "movq %%rax, %%rcx \n\t" // make another copy of Eflag in rcx + "xorl $0x200000, %%eax \n\t" // toggle ID bit in Eflag (i.e., bit 21) + "pushq %%rax \n\t" // save modified Eflag back to stack + "popfq \n\t" // restore modified value to Eflag reg + "pushfq \n\t" // save Eflag to stack + "popq %%rax \n\t" // get Eflag from stack + "pushq %%rcx \n\t" // save original Eflag to stack + "popfq \n\t" // restore original Eflag +#else + "pushl %%ebx \n\t" // ebx gets clobbered by CPUID instruction + "pushl %%ecx \n\t" // so does ecx... + "pushl %%edx \n\t" // ...and edx (but ecx & edx safe on Linux) + "pushfl \n\t" // save Eflag to stack + "popl %%eax \n\t" // get Eflag from stack into eax + "movl %%eax, %%ecx \n\t" // make another copy of Eflag in ecx + "xorl $0x200000, %%eax \n\t" // toggle ID bit in Eflag (i.e., bit 21) + "pushl %%eax \n\t" // save modified Eflag back to stack + "popfl \n\t" // restore modified value to Eflag reg + "pushfl \n\t" // save Eflag to stack + "popl %%eax \n\t" // get Eflag from stack + "pushl %%ecx \n\t" // save original Eflag to stack + "popfl \n\t" // restore original Eflag +#endif + "xorl %%ecx, %%eax \n\t" // compare new Eflag with original Eflag + "jz 0f \n\t" // if same, CPUID instr. is not supported + + "xorl %%eax, %%eax \n\t" // set eax to zero +// ".byte 0x0f, 0xa2 \n\t" // CPUID instruction (two-byte opcode) + "cpuid \n\t" // get the CPU identification info + "cmpl $1, %%eax \n\t" // make sure eax return non-zero value + "jl 0f \n\t" // if eax is zero, MMX is not supported + + "xorl %%eax, %%eax \n\t" // set eax to zero and... + "incl %%eax \n\t" // ...increment eax to 1. This pair is + // faster than the instruction "mov eax, 1" + "cpuid \n\t" // get the CPU identification info again + "andl $0x800000, %%edx \n\t" // mask out all bits but MMX bit (23) + "cmpl $0, %%edx \n\t" // 0 = MMX not supported + "jz 0f \n\t" // non-zero = yes, MMX IS supported + + "movl $1, %%eax \n\t" // set return value to 1 + "jmp 1f \n\t" // DONE: have MMX support + + "0: \n\t" // .NOT_SUPPORTED: target label for jump instructions + "movl $0, %%eax \n\t" // set return value to 0 + "1: \n\t" // .RETURN: target label for jump instructions +#if defined(__x86_64__) + "popq %%rdx \n\t" // restore rdx + "popq %%rcx \n\t" // restore rcx + "popq %%rbx \n\t" // restore rbx +#else + "popl %%edx \n\t" // restore edx + "popl %%ecx \n\t" // restore ecx + "popl %%ebx \n\t" // restore ebx +#endif + +// "ret \n\t" // DONE: no MMX support + // (fall through to standard C "ret") + + : "=a" (result) // output list + + : // any variables used on input (none) + + // no clobber list +// , "%ebx", "%ecx", "%edx" // GRR: we handle these manually +// , "memory" // if write to a variable gcc thought was in a reg +// , "cc" // "condition codes" (flag bits) + ); + _mmx_supported = result; +#else + _mmx_supported = 0; +#endif /* PNG_MMX_CODE_SUPPORTED */ + + return _mmx_supported; +} +#endif |