kc3-lang/libjpeg-turbo/jsimdgcc.c

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• Hash : a2e6a9dd
  Author :
  Date : 2006-02-04T00:00:00
  

  IJG R6b with x86SIMD V1.02
  Independent JPEG Group's JPEG software release 6b
  with x86 SIMD extension for IJG JPEG library version 1.02
  

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• jsimdgcc.c

• /*
   * jsimdgcc.c - SIMD instruction support check (gcc)
   *
   * x86 SIMD extension for IJG JPEG library
   * Copyright (C) 1999-2006, MIYASAKA Masaru.
   * For conditions of distribution and use, see copyright notice in jsimdext.inc
   *
   * Last Modified : January 24, 2006
   */
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "jpeglib.h"
  
  #include <setjmp.h>
  #include <signal.h>
  
  
  static volatile int lockf /* = 0 */;
  static jmp_buf jmpbuf;
  
  
  /*
   * Exception handler for signal()
   */
  
  LOCAL(void)
  exception_handler (int sig)
  {
    signal(SIGILL, SIG_DFL);
    longjmp(jmpbuf, 1);
  }
  
  
  /*
   * Check if the OS supports SIMD instructions
   */
  
  GLOBAL(unsigned int)
  jpeg_simd_os_support (unsigned int simd)
  {
  #ifdef __GNUC__		/* gcc (i386) */
    unsigned int mxcsr = 0x1F80;
  
    /* enter critical section */
    __asm__ __volatile__ (
    "get_lock:                  \n\t"
      "movl  $1,%%eax           \n\t"
      "xchgl %0,%%eax           \n\t"	/* try to get lock */
      "cmpl  $0,%%eax           \n\t"	/* test if successful */
      "je    critical_section   \n"
    "spin_loop:                 \n\t"
    /*".byte 0xF3,0x90          \n\t"*/	/* "pause" on P4 (short delay) */
      "cmpl  $0,%0              \n\t"	/* check if lock is free */
      "jne   spin_loop          \n\t"
      "jmp   get_lock           \n"
    "critical_section:          \n\t"
       : "=m" (lockf) : "m" (lockf) : "%eax"
    );
  
    /* If floating point emulation is enabled (CR0.EM = 1),
     * executing an MMX/3DNow! instruction generates invalid
     * opcode exception (#UD).
     */
    if (simd & (JSIMD_MMX | JSIMD_3DNOW)) {
      if (!setjmp(jmpbuf)) {
        signal(SIGILL, exception_handler);
        __asm__ __volatile__ (
          ".byte 0x0F,0x77"		/* emms */
        );
        signal(SIGILL, SIG_DFL);
      } else {
        simd &= ~(JSIMD_MMX | JSIMD_3DNOW);
      }
    }
    if (simd & (JSIMD_SSE | JSIMD_SSE2)) {
      if (!setjmp(jmpbuf)) {
        signal(SIGILL, exception_handler);
        __asm__ __volatile__ (
          "leal  %0,%%eax        \n\t"
          ".byte 0x0F,0xAE,0x10  \n\t"	/* ldmxcsr [eax] */
           : : "m" (mxcsr) : "%eax"
        );
        signal(SIGILL, SIG_DFL);
      } else {
        simd &= ~(JSIMD_SSE | JSIMD_SSE2);
      }
    }
  
    /* leave critical section */
    lockf = 0;	/* release lock */
  #endif	/* __GNUC__ */
  
    return simd;
  }
  

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