a2e6a9dd47
Independent JPEG Group's JPEG software release 6b with x86 SIMD extension for IJG JPEG library version 1.02
96 lines
2.2 KiB
C
96 lines
2.2 KiB
C
/*
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* jsimdgcc.c - SIMD instruction support check (gcc)
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*
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* x86 SIMD extension for IJG JPEG library
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* Copyright (C) 1999-2006, MIYASAKA Masaru.
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* For conditions of distribution and use, see copyright notice in jsimdext.inc
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*
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* Last Modified : January 24, 2006
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*/
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#define JPEG_INTERNALS
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#include "jinclude.h"
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#include "jpeglib.h"
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#include <setjmp.h>
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#include <signal.h>
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static volatile int lockf /* = 0 */;
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static jmp_buf jmpbuf;
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/*
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* Exception handler for signal()
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*/
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LOCAL(void)
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exception_handler (int sig)
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{
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signal(SIGILL, SIG_DFL);
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longjmp(jmpbuf, 1);
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}
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/*
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* Check if the OS supports SIMD instructions
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*/
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GLOBAL(unsigned int)
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jpeg_simd_os_support (unsigned int simd)
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{
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#ifdef __GNUC__ /* gcc (i386) */
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unsigned int mxcsr = 0x1F80;
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/* enter critical section */
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__asm__ __volatile__ (
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"get_lock: \n\t"
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"movl $1,%%eax \n\t"
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"xchgl %0,%%eax \n\t" /* try to get lock */
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"cmpl $0,%%eax \n\t" /* test if successful */
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"je critical_section \n"
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"spin_loop: \n\t"
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/*".byte 0xF3,0x90 \n\t"*/ /* "pause" on P4 (short delay) */
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"cmpl $0,%0 \n\t" /* check if lock is free */
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"jne spin_loop \n\t"
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"jmp get_lock \n"
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"critical_section: \n\t"
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: "=m" (lockf) : "m" (lockf) : "%eax"
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);
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/* If floating point emulation is enabled (CR0.EM = 1),
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* executing an MMX/3DNow! instruction generates invalid
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* opcode exception (#UD).
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*/
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if (simd & (JSIMD_MMX | JSIMD_3DNOW)) {
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if (!setjmp(jmpbuf)) {
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signal(SIGILL, exception_handler);
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__asm__ __volatile__ (
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".byte 0x0F,0x77" /* emms */
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);
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signal(SIGILL, SIG_DFL);
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} else {
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simd &= ~(JSIMD_MMX | JSIMD_3DNOW);
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}
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}
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if (simd & (JSIMD_SSE | JSIMD_SSE2)) {
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if (!setjmp(jmpbuf)) {
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signal(SIGILL, exception_handler);
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__asm__ __volatile__ (
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"leal %0,%%eax \n\t"
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".byte 0x0F,0xAE,0x10 \n\t" /* ldmxcsr [eax] */
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: : "m" (mxcsr) : "%eax"
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);
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signal(SIGILL, SIG_DFL);
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} else {
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simd &= ~(JSIMD_SSE | JSIMD_SSE2);
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}
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}
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/* leave critical section */
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lockf = 0; /* release lock */
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#endif /* __GNUC__ */
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return simd;
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}
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