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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 |