| /* pnggccrd.c was removed from libpng-1.2.20. */ |
| |
| /* This code snippet is for use by configure's compilation test. */ |
| |
| #if (!defined _MSC_VER) && \ |
| 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 |
