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