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med640x8.c

/*
  Hatari - med640x8.c
 
  This file is distributed under the GNU Public License, version 2 or at your
  option any later version. Read the file gpl.txt for details.

  Screen conversion, Medium Res to 640x8Bit
*/

static void ConvertMediumRes_640x8Bit(void)
{
  Uint32 *edi, *ebp;
  Uint32 *esi;
  Uint32 eax;
  int y;

  Convert_StartFrame();          /* Start frame, track palettes */

  for (y = STScreenStartHorizLine; y < STScreenEndHorizLine; y++) {

    eax = STScreenLineOffset[y] + STScreenLeftSkipBytes;  /* Offset for this line + Amount to skip on left hand side */
    edi = (Uint32 *)((Uint8 *)pSTScreen + eax);       /* ST format screen 4-plane 16 colours */
    ebp = (Uint32 *)((Uint8 *)pSTScreenCopy + eax);   /* Previous ST format screen */
    esi = (Uint32 *)pPCScreenDest;                    /* PC format screen */

    if((AdjustLinePaletteRemap(y) & 0x00030000) == 0)    /* Change palette table */
      Line_ConvertLowRes_640x8Bit(edi, ebp, esi, eax);
    else
      Line_ConvertMediumRes_640x8Bit(edi, ebp, esi, eax);

    pPCScreenDest = (void *)(((Uint8 *)pPCScreenDest)+PCScreenBytesPerLine*2);  /* Offset to next line */
  }
}


static void Line_ConvertMediumRes_640x8Bit(Uint32 *edi, Uint32 *ebp, Uint32 *esi, Uint32 eax)
{
  Uint32 ebx, ecx;
  int x;

  x = STScreenWidthBytes>>2;   /* Amount to draw across in 16-pixels (4 bytes) */

  do    /* x-loop */
  {

    /* Do 16 pixels at one time */
    ebx = *edi;

    if((ScrUpdateFlag&0xe0000000) || ebx!=*ebp)       /* Does differ? */
    {  /* copy word */

      bScreenContentsChanged = TRUE;

#if SDL_BYTEORDER == SDL_BIG_ENDIAN
      /* Plot in 'right-order' on big endian systems */
      if(!bScrDoubleY)                  /* Double on Y? */
      {
        MED_BUILD_PIXELS_0 ;            /* Generate 'ecx' as pixels [4,5,6,7] */
        PLOT_MED_640_8BIT(3) ;
        MED_BUILD_PIXELS_1 ;            /* Generate 'ecx' as pixels [12,13,14,15] */
        PLOT_MED_640_8BIT(1) ;
        MED_BUILD_PIXELS_2 ;            /* Generate 'ecx' as pixels [0,1,2,3] */
        PLOT_MED_640_8BIT(2) ;
        MED_BUILD_PIXELS_3 ;            /* Generate 'ecx' as pixels [8,9,10,11] */
        PLOT_MED_640_8BIT(0) ;
      }
      else
      {
        MED_BUILD_PIXELS_0 ;            /* Generate 'ecx' as pixels [4,5,6,7] */
        PLOT_MED_640_8BIT_DOUBLE_Y(3) ;
        MED_BUILD_PIXELS_1 ;            /* Generate 'ecx' as pixels [12,13,14,15] */
        PLOT_MED_640_8BIT_DOUBLE_Y(1) ;
        MED_BUILD_PIXELS_2 ;            /* Generate 'ecx' as pixels [0,1,2,3] */
        PLOT_MED_640_8BIT_DOUBLE_Y(2) ;
        MED_BUILD_PIXELS_3 ;            /* Generate 'ecx' as pixels [8,9,10,11] */
        PLOT_MED_640_8BIT_DOUBLE_Y(0) ;
      }
#else
      /* Plot in 'wrong-order', as ebx is 68000 endian */
      if(!bScrDoubleY)                  /* Double on Y? */
      {
        MED_BUILD_PIXELS_0 ;            /* Generate 'ecx' as pixels [4,5,6,7] */
        PLOT_MED_640_8BIT(1) ;
        MED_BUILD_PIXELS_1 ;            /* Generate 'ecx' as pixels [12,13,14,15] */
        PLOT_MED_640_8BIT(3) ;
        MED_BUILD_PIXELS_2 ;            /* Generate 'ecx' as pixels [0,1,2,3] */
        PLOT_MED_640_8BIT(0) ;
        MED_BUILD_PIXELS_3 ;            /* Generate 'ecx' as pixels [8,9,10,11] */
        PLOT_MED_640_8BIT(2) ;
      }
      else
      {
        MED_BUILD_PIXELS_0 ;            /* Generate 'ecx' as pixels [4,5,6,7] */
        PLOT_MED_640_8BIT_DOUBLE_Y(1) ;
        MED_BUILD_PIXELS_1 ;            /* Generate 'ecx' as pixels [12,13,14,15] */
        PLOT_MED_640_8BIT_DOUBLE_Y(3) ;
        MED_BUILD_PIXELS_2 ;            /* Generate 'ecx' as pixels [0,1,2,3] */
        PLOT_MED_640_8BIT_DOUBLE_Y(0) ;
        MED_BUILD_PIXELS_3 ;            /* Generate 'ecx' as pixels [8,9,10,11] */
        PLOT_MED_640_8BIT_DOUBLE_Y(2) ;
      }
#endif
    }

    esi += 4;                           /* Next PC pixels */
    edi += 1;                           /* Next ST pixels */
    ebp += 1;                           /* Next ST copy pixels */
  
  }
  while(--x);                        /* Loop on X */
}

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