/* pngvcrd.c - mixed C/assembler version of utilities to read a PNG file * * For Intel x86 CPU and Microsoft Visual C++ compiler * * libpng 1.0.12 - June 8, 2001 * For conditions of distribution and use, see copyright notice in png.h * Copyright (c) 1998-2001 Glenn Randers-Pehrson * Copyright (c) 1998, Intel Corporation * * Contributed by Nirav Chhatrapati, Intel Corporation, 1998 * Interface to libpng contributed by Gilles Vollant, 1999 * Debugging and cleanup by Greg Roelofs, 2000, 2001 * * In png_do_read_interlace() in libpng versions 1.0.3a through 1.0.4d, * a sign error in the post-MMX cleanup code for each pixel_depth resulted * in bad pixels at the beginning of some rows of some images, and also * (due to out-of-range memory reads and writes) caused heap corruption * when compiled with MSVC 6.0.  The error was fixed in version 1.0.4e. * * [png_read_filter_row_mmx_avg() bpp == 2 bugfix, GRR 20000916] * */#define PNG_INTERNAL#include "png.h"#if defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_USE_PNGVCRD)static int mmx_supported=2;int PNGAPIpng_mmx_support(void){  int mmx_supported_local = 0;  _asm {    push ebx          //CPUID will trash these    push ecx    push edx    pushfd            //Save Eflag to stack    pop eax           //Get Eflag from stack into eax    mov ecx, eax      //Make another copy of Eflag in ecx    xor eax, 0x200000 //Toggle ID bit in Eflag [i.e. bit(21)]    push eax          //Save modified Eflag back to stack    popfd             //Restored modified value back to Eflag reg    pushfd            //Save Eflag to stack    pop eax           //Get Eflag from stack    xor eax, ecx      //Compare the new Eflag with the original Eflag    jz NOT_SUPPORTED  //If the same, CPUID instruction is not supported,                      //skip following instructions and jump to                      //NOT_SUPPORTED label    xor eax, eax      //Set eax to zero    _asm _emit 0x0f   //CPUID instruction  (two bytes opcode)    _asm _emit 0xa2    cmp eax, 1        //make sure eax return non-zero value    jl NOT_SUPPORTED  //If eax is zero, mmx not supported    xor eax, eax      //set eax to zero    inc eax           //Now increment eax to 1.  This instruction is                      //faster than the instruction "mov eax, 1"    _asm _emit 0x0f   //CPUID instruction    _asm _emit 0xa2    and edx, 0x00800000  //mask out all bits but mmx bit(24)    cmp edx, 0        // 0 = mmx not supported    jz  NOT_SUPPORTED // non-zero = Yes, mmx IS supported    mov  mmx_supported_local, 1  //set return value to 1NOT_SUPPORTED:    mov  eax, mmx_supported_local  //move return value to eax    pop edx          //CPUID trashed these    pop ecx    pop ebx  }  //mmx_supported_local=0; // test code for force don't support MMX  //printf("MMX : %u (1=MMX supported)\n",mmx_supported_local);  mmx_supported = mmx_supported_local;  return mmx_supported_local;}/* Combines the row recently read in with the previous row.   This routine takes care of alpha and transparency if requested.   This routine also handles the two methods of progressive display   of interlaced images, depending on the mask value.   The mask value describes which pixels are to be combined with   the row.  The pattern always repeats every 8 pixels, so just 8   bits are needed.  A one indicates the pixel is to be combined; a   zero indicates the pixel is to be skipped.  This is in addition   to any alpha or transparency value associated with the pixel.  If   you want all pixels to be combined, pass 0xff (255) in mask.  *//* Use this routine for x86 platform - uses faster MMX routine if machine   supports MMX */void /* PRIVATE */png_combine_row(png_structp png_ptr, png_bytep row, int mask){#ifdef PNG_USE_LOCAL_ARRAYS   const int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};#endif   png_debug(1,"in png_combine_row_asm\n");   if (mmx_supported == 2) {       png_mmx_support();   }   if (mask == 0xff)   {      png_memcpy(row, png_ptr->row_buf + 1,       (png_size_t)((png_ptr->width * png_ptr->row_info.pixel_depth + 7) >> 3));   }   /* GRR:  add "else if (mask == 0)" case?    *       or does png_combine_row() not even get called in that case? */   else   {      switch (png_ptr->row_info.pixel_depth)      {         case 1:         {            png_bytep sp;            png_bytep dp;            int s_inc, s_start, s_end;            int m;            int shift;            png_uint_32 i;            sp = png_ptr->row_buf + 1;            dp = row;            m = 0x80;#if defined(PNG_READ_PACKSWAP_SUPPORTED)            if (png_ptr->transformations & PNG_PACKSWAP)            {                s_start = 0;                s_end = 7;                s_inc = 1;            }            else#endif            {                s_start = 7;                s_end = 0;                s_inc = -1;            }            shift = s_start;            for (i = 0; i < png_ptr->width; i++)            {               if (m & mask)               {                  int value;                  value = (*sp >> shift) & 0x1;                  *dp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);                  *dp |= (png_byte)(value << shift);               }               if (shift == s_end)               {                  shift = s_start;                  sp++;                  dp++;               }               else                  shift += s_inc;               if (m == 1)                  m = 0x80;               else                  m >>= 1;            }            break;         }         case 2:         {            png_bytep sp;            png_bytep dp;            int s_start, s_end, s_inc;            int m;            int shift;            png_uint_32 i;            int value;            sp = png_ptr->row_buf + 1;            dp = row;            m = 0x80;#if defined(PNG_READ_PACKSWAP_SUPPORTED)            if (png_ptr->transformations & PNG_PACKSWAP)            {               s_start = 0;               s_end = 6;               s_inc = 2;            }            else#endif            {               s_start = 6;               s_end = 0;               s_inc = -2;            }            shift = s_start;            for (i = 0; i < png_ptr->width; i++)            {               if (m & mask)               {                  value = (*sp >> shift) & 0x3;                  *dp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);                  *dp |= (png_byte)(value << shift);               }               if (shift == s_end)               {                  shift = s_start;                  sp++;                  dp++;               }               else                  shift += s_inc;               if (m == 1)                  m = 0x80;               else                  m >>= 1;            }            break;         }         case 4:         {            png_bytep sp;            png_bytep dp;            int s_start, s_end, s_inc;            int m;            int shift;            png_uint_32 i;            int value;            sp = png_ptr->row_buf + 1;            dp = row;            m = 0x80;#if defined(PNG_READ_PACKSWAP_SUPPORTED)            if (png_ptr->transformations & PNG_PACKSWAP)            {               s_start = 0;               s_end = 4;               s_inc = 4;            }            else#endif            {               s_start = 4;               s_end = 0;               s_inc = -4;            }            shift = s_start;            for (i = 0; i < png_ptr->width; i++)            {               if (m & mask)               {                  value = (*sp >> shift) & 0xf;                  *dp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);                  *dp |= (png_byte)(value << shift);               }               if (shift == s_end)               {                  shift = s_start;                  sp++;                  dp++;               }               else                  shift += s_inc;               if (m == 1)                  m = 0x80;               else                  m >>= 1;            }            break;         }         case 8:         {            png_bytep srcptr;            png_bytep dstptr;            png_uint_32 len;            int m;            int diff, unmask;            __int64 mask0=0x0102040810204080;            if ( mmx_supported )            {               srcptr = png_ptr->row_buf + 1;               dstptr = row;               m = 0x80;               unmask = ~mask;               len  = png_ptr->width &~7;  //reduce to multiple of 8               diff = png_ptr->width & 7;  //amount lost               _asm               {                  movd       mm7, unmask   //load bit pattern                  psubb      mm6,mm6       //zero mm6                  punpcklbw  mm7,mm7                  punpcklwd  mm7,mm7                  punpckldq  mm7,mm7       //fill register with 8 masks                  movq       mm0,mask0                  pand       mm0,mm7       //nonzero if keep byte                  pcmpeqb    mm0,mm6       //zeros->1s, v versa                  mov        ecx,len       //load length of line (pixels)                  mov        esi,srcptr    //load source                  mov        ebx,dstptr    //load dest                  cmp        ecx,0         //lcr                  je         mainloop8endmainloop8:                  movq       mm4,[esi]                  pand       mm4,mm0                  movq       mm6,mm0                  pandn      mm6,[ebx]                  por        mm4,mm6                  movq       [ebx],mm4                  add        esi,8         //inc by 8 bytes processed                  add        ebx,8                  sub        ecx,8         //dec by 8 pixels processed                  ja         mainloop8mainloop8end:                  mov        ecx,diff                  cmp        ecx,0                  jz         end8                  mov        edx,mask                  sal        edx,24        //make low byte the high bytesecondloop8:                  sal        edx,1         //move high bit to CF                  jnc        skip8         //if CF = 0                  mov        al,[esi]                  mov        [ebx],alskip8:                  inc        esi                  inc        ebx                  dec        ecx                  jnz        secondloop8end8:                  emms               }            }            else /* mmx not supported - use modified C routine */            {               register unsigned int incr1, initial_val, final_val;               png_size_t pixel_bytes;               png_uint_32 i;