xref: /reactos/win32ss/gdi/dib/dib24bppc.c (revision c2c66aff)

/*
 * PROJECT:         Win32 subsystem
 * LICENSE:         See COPYING in the top level directory
 * FILE:            win32ss/gdi/dib/dib24bppc.c
 * PURPOSE:         C language equivalents of asm optimised 24bpp functions
 * PROGRAMMERS:     Jason Filby
 *                  Magnus Olsen
 */

#include <win32k.h>

#define NDEBUG
#include <debug.h>

VOID
DIB_24BPP_HLine(SURFOBJ *SurfObj, LONG x1, LONG x2, LONG y, ULONG c)
{
  PBYTE addr = (PBYTE)SurfObj->pvScan0 + y * SurfObj->lDelta + (x1 << 1) + x1;
  ULONG Count = x2 - x1;

  if (Count < 8)
  {
    /* For small fills, don't bother doing anything fancy */
    while (Count--)
    {
      *(PUSHORT)(addr) = c;
      addr += 2;
      *(addr) = c >> 16;
      addr += 1;
    }
  }
  else
  {
    ULONG Fill[3];
    ULONG MultiCount;

    /* Align to 4-byte address */
    while (0 != ((ULONG_PTR) addr & 0x3))
    {
      *(PUSHORT)(addr) = c;
      addr += 2;
      *(addr) = c >> 16;
      addr += 1;
      Count--;
    }
    /* If the color we need to fill with is 0ABC, then the final mem pattern
    * (note little-endianness) would be:
    *
    * |C.B.A|C.B.A|C.B.A|C.B.A|   <- pixel borders
    * |C.B.A.C|B.A.C.B|A.C.B.A|   <- ULONG borders
    *
    * So, taking endianness into account again, we need to fill with these
    * ULONGs: CABC BCAB ABCA */

    c = c & 0xffffff;                /* 0ABC */
    Fill[0] = c | (c << 24);         /* CABC */
    Fill[1] = (c >> 8) | (c << 16);  /* BCAB */
    Fill[2] = (c << 8) | (c >> 16);  /* ABCA */
    MultiCount = Count / 4;
    do
    {
      *(PULONG)addr = Fill[0];
      addr += 4;
      *(PULONG)addr = Fill[1];
      addr += 4;
      *(PULONG)addr = Fill[2];
      addr += 4;
    }
    while (0 != --MultiCount);

    Count = Count & 0x03;
    while (0 != Count--)
    {
      *(PUSHORT)(addr) = c;
      addr += 2;
      *(addr) = c >> 16;
      addr += 1;
    }
  }
}