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