pnggccrd.c
Go to the documentation of this file.
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 #if defined(PNG_MMX_CODE_SUPPORTED) // superfluous, but what the heck
21  __asm__ __volatile__ (
22 #if defined(__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 #if defined(__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
PNGAPI
#define PNGAPI
Definition: pngconf.h:1386

openhrp3
Author(s): AIST, General Robotix Inc., Nakamura Lab of Dept. of Mechano Informatics at University of Tokyo
autogenerated on Sat Apr 13 2019 02:14:24