1 /* pnggccrd.c was removed from libpng-1.2.20. */ 2 3 /* This code snippet is for use by configure's compilation test. */ 4 5 #if (!defined _MSC_VER) && \ 6 defined(PNG_ASSEMBLER_CODE_SUPPORTED) && \ 7 defined(PNG_MMX_CODE_SUPPORTED) 8 9 int PNGAPI png_dummy_mmx_support(void); 10 11 static int _mmx_supported = 2; // 0: no MMX; 1: MMX supported; 2: not tested 12 13 int PNGAPI 14 png_dummy_mmx_support(void) __attribute__((noinline)); 15 16 int PNGAPI 17 png_dummy_mmx_support(void) 18 { 19 int result; 20 #ifdef PNG_MMX_CODE_SUPPORTED // superfluous, but what the heck 21 __asm__ __volatile__ ( 22 #ifdef __x86_64__ 23 "pushq %%rbx \n\t" // rbx gets clobbered by CPUID instruction 24 "pushq %%rcx \n\t" // so does rcx... 25 "pushq %%rdx \n\t" // ...and rdx (but rcx & rdx safe on Linux) 26 "pushfq \n\t" // save Eflag to stack 27 "popq %%rax \n\t" // get Eflag from stack into rax 28 "movq %%rax, %%rcx \n\t" // make another copy of Eflag in rcx 29 "xorl $0x200000, %%eax \n\t" // toggle ID bit in Eflag (i.e., bit 21) 30 "pushq %%rax \n\t" // save modified Eflag back to stack 31 "popfq \n\t" // restore modified value to Eflag reg 32 "pushfq \n\t" // save Eflag to stack 33 "popq %%rax \n\t" // get Eflag from stack 34 "pushq %%rcx \n\t" // save original Eflag to stack 35 "popfq \n\t" // restore original Eflag 36 #else 37 "pushl %%ebx \n\t" // ebx gets clobbered by CPUID instruction 38 "pushl %%ecx \n\t" // so does ecx... 39 "pushl %%edx \n\t" // ...and edx (but ecx & edx safe on Linux) 40 "pushfl \n\t" // save Eflag to stack 41 "popl %%eax \n\t" // get Eflag from stack into eax 42 "movl %%eax, %%ecx \n\t" // make another copy of Eflag in ecx 43 "xorl $0x200000, %%eax \n\t" // toggle ID bit in Eflag (i.e., bit 21) 44 "pushl %%eax \n\t" // save modified Eflag back to stack 45 "popfl \n\t" // restore modified value to Eflag reg 46 "pushfl \n\t" // save Eflag to stack 47 "popl %%eax \n\t" // get Eflag from stack 48 "pushl %%ecx \n\t" // save original Eflag to stack 49 "popfl \n\t" // restore original Eflag 50 #endif 51 "xorl %%ecx, %%eax \n\t" // compare new Eflag with original Eflag 52 "jz 0f \n\t" // if same, CPUID instr. is not supported 53 54 "xorl %%eax, %%eax \n\t" // set eax to zero 55 // ".byte 0x0f, 0xa2 \n\t" // CPUID instruction (two-byte opcode) 56 "cpuid \n\t" // get the CPU identification info 57 "cmpl $1, %%eax \n\t" // make sure eax return non-zero value 58 "jl 0f \n\t" // if eax is zero, MMX is not supported 59 60 "xorl %%eax, %%eax \n\t" // set eax to zero and... 61 "incl %%eax \n\t" // ...increment eax to 1. This pair is 62 // faster than the instruction "mov eax, 1" 63 "cpuid \n\t" // get the CPU identification info again 64 "andl $0x800000, %%edx \n\t" // mask out all bits but MMX bit (23) 65 "cmpl $0, %%edx \n\t" // 0 = MMX not supported 66 "jz 0f \n\t" // non-zero = yes, MMX IS supported 67 68 "movl $1, %%eax \n\t" // set return value to 1 69 "jmp 1f \n\t" // DONE: have MMX support 70 71 "0: \n\t" // .NOT_SUPPORTED: target label for jump instructions 72 "movl $0, %%eax \n\t" // set return value to 0 73 "1: \n\t" // .RETURN: target label for jump instructions 74 #ifdef __x86_64__ 75 "popq %%rdx \n\t" // restore rdx 76 "popq %%rcx \n\t" // restore rcx 77 "popq %%rbx \n\t" // restore rbx 78 #else 79 "popl %%edx \n\t" // restore edx 80 "popl %%ecx \n\t" // restore ecx 81 "popl %%ebx \n\t" // restore ebx 82 #endif 83 84 // "ret \n\t" // DONE: no MMX support 85 // (fall through to standard C "ret") 86 87 : "=a" (result) // output list 88 89 : // any variables used on input (none) 90 91 // no clobber list 92 // , "%ebx", "%ecx", "%edx" // GRR: we handle these manually 93 // , "memory" // if write to a variable gcc thought was in a reg 94 // , "cc" // "condition codes" (flag bits) 95 ); 96 _mmx_supported = result; 97 #else 98 _mmx_supported = 0; 99 #endif /* PNG_MMX_CODE_SUPPORTED */ 100 101 return _mmx_supported; 102 } 103 #endif 104
