/*
  Hatari - low320x8.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 function, Low Res to 320x8Bit
*/

static void ConvertLowRes_320x8Bit(void)
{
  Uint32 *edi, *ebp;
  Uint32 *esi;
  Uint32 eax, edx;
  Uint32 ebx, ecx;
  int y, x, update;

  edx = 0;

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

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

    /* Get screen addresses, 'edi'-ST screen, 'ebp'-Previous ST screen, 'esi'-PC screen */
    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, byte per pixel 256 colors */

    update = AdjustLinePaletteRemap(y) & PALETTEMASK_UPDATEMASK;

    x = STScreenWidthBytes>>3;   /* Amount to draw across in 16-pixels(8 bytes) */

    do    /* x-loop */
    {
      /* Do 16 pixels at one time */
      ebx = *edi;
      ecx = *(edi+1);

      if(update || ebx!=*ebp || ecx!=*(ebp+1))  /* Does differ? */
      { /* copy word */

        bScreenContentsChanged = TRUE;
   
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
        /* Plot pixels */
        LOW_BUILD_PIXELS_0 ;    /* Generate 'ecx' as pixels [4,5,6,7] */
        PLOT_LOW_320_8BIT(3) ;
        LOW_BUILD_PIXELS_1 ;    /* Generate 'ecx' as pixels [12,13,14,15] */
        PLOT_LOW_320_8BIT(1) ;
        LOW_BUILD_PIXELS_2 ;    /* Generate 'ecx' as pixels [0,1,2,3] */
        PLOT_LOW_320_8BIT(2) ;
        LOW_BUILD_PIXELS_3 ;    /* Generate 'ecx' as pixels [8,9,10,11] */
        PLOT_LOW_320_8BIT(0) ;
#else
        /* Plot pixels */
        LOW_BUILD_PIXELS_0 ;    /* Generate 'ecx' as pixels [4,5,6,7] */
        PLOT_LOW_320_8BIT(1) ;
        LOW_BUILD_PIXELS_1 ;    /* Generate 'ecx' as pixels [12,13,14,15] */
        PLOT_LOW_320_8BIT(3) ;
        LOW_BUILD_PIXELS_2 ;    /* Generate 'ecx' as pixels [0,1,2,3] */
        PLOT_LOW_320_8BIT(0) ;
        LOW_BUILD_PIXELS_3 ;    /* Generate 'ecx' as pixels [8,9,10,11] */
        PLOT_LOW_320_8BIT(2) ;
#endif
      }

      esi += 4;                 /* Next PC pixels */
      edi += 2;                 /* Next ST pixels */
      ebp += 2;                 /* Next ST copy pixels */
    }
    while(--x);              /* Loop on X */

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