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blitters.cpp

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2005-2006 Neil Millstone
 * Copyright (C) 2006 The ScummVM project
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 */
 
#include "stdafx.h"
#define CHARSET_MASK_TRANSPARENCY 253

namespace DS {

void asmDrawStripToScreen(int height, int width, byte const* text, byte const* src, byte* dst, 
      int vsPitch, int vmScreenWidth, int textSurfacePitch) {


      if (height <= 0) height = 1;
      if (width < 4) return;
      
      
      width &= ~4;
//    src = (const byte *) (((int) (src)) & (~4));
//    dst = (byte *) (((int) (dst)) & (~4));
//    text = (const byte *) (((int) (text)) & (~4));
      
      asm ( "mov r5, %0\n"                      // Height
                  "yLoop:\n"              
                  "mov r3, #0\n"                      // X pos
                  
                  "xLoop:\n"
                  
                  "ldr r4, [%2, r3]\n"          // Load text layer word
                  "cmp r4, %5\n"
                  "bne singleByteCompare\n"
                  "ldr r4, [%3, r3]\n"
                  "str r4, [%4, r3]\n"
                  "add r3, r3, #4\n"
                  "cmp r3, %1\n"                      // x == width?
                  "blt xLoop\n"
                  
                  "add %2, %2, %8\n"                  // src += vs->pitch
                  "add %3, %3, %6\n"                  // dst += _vm->_screenWidth
                  "add %4, %4, %7\n"                  // text += _textSurface.pitch
                  "sub r5, r5, #1\n"                  // y -= 1
                  "cmp r5, #0\n"                      // y == 0?
                  "bne yLoop\n"
                  "b end\n"
                  
                  
                  "singleByteCompare:\n"
                  "ldrb r4, [%2, r3]\n"         // Load text byte
                  "cmps r4, %5, lsr #24\n"      // Compare with mask
                  "strneb r4, [%4, r3]\n"       // Store if not equal
                  "ldreqb r4, [%3, r3]\n"       // Otherwise Load src byte
                  "streqb r4, [%4, r3]\n"       // Store it
                  "add r3, r3, #1\n"

                  "ldrb r4, [%2, r3]\n"         // Load text byte
                  "cmps r4, %5, lsr #24\n"      // Compare with mask
                  "strneb r4, [%4, r3]\n"       // Store if not equal
                  "ldreqb r4, [%3, r3]\n"       // Otherwise Load src byte
                  "streqb r4, [%4, r3]\n"       // Store it
                  "add r3, r3, #1\n"
                  
                  "ldrb r4, [%2, r3]\n"         // Load text byte
                  "cmps r4, %5, lsr #24\n"      // Compare with mask
                  "strneb r4, [%4, r3]\n"       // Store if not equal
                  "ldreqb r4, [%3, r3]\n"       // Otherwise Load src byte
                  "streqb r4, [%4, r3]\n"       // Store it
                  "add r3, r3, #1\n"

                  "ldrb r4, [%2, r3]\n"         // Load text byte
                  "cmps r4, %5, lsr #24\n"      // Compare with mask
                  "strneb r4, [%4, r3]\n"       // Store if not equal
                  "ldreqb r4, [%3, r3]\n"       // Otherwise Load src byte
                  "streqb r4, [%4, r3]\n"       // Store it
                  "add r3, r3, #1\n"                  

                  "cmps r3, %1\n"                     // x == width?
                  "blt xLoop\n"                       // Repeat
                  "add %2, %2, %8\n"                  // src += vs->pitch
                  "add %3, %3, %6\n"                  // dst += _vm->_screenWidth
                  "add %4, %4, %7\n"                  // text += _textSurface.pitch
                  "sub r5, r5, #1\n"                  // y -= 1
                  "cmp r5, #0\n"                      // y == 0?
                  "bne yLoop\n"
                  
                  "end:\n"
            : /* no output registers */
            : "r" (height), "r" (width), "r" (text), "r" (src), "r" (dst), "r" (CHARSET_MASK_TRANSPARENCY | (CHARSET_MASK_TRANSPARENCY << 8) | (CHARSET_MASK_TRANSPARENCY << 16) | (CHARSET_MASK_TRANSPARENCY << 24)), 
                  "r" (vsPitch), "r" (vmScreenWidth), "r" (textSurfacePitch)
            : "r5", "r3", "r4", "%2", "%3", "%4", "memory");
}



void asmCopy8Col(byte* dst, int dstPitch, const byte* src, int height) {
      asm("ands r0, %3, #1\n"
             "addne %3, %3, #1\n"
             "bne roll2\n"
                  
             "yLoop2:\n"
             "ldr r0, [%2, #0]\n"
             "str r0, [%0, #0]\n"
             "ldr r0, [%2, #4]\n"
             "str r0, [%0, #4]\n"
             "add %0, %0, %1\n"
             "add %2, %2, %1\n"
             "roll2:\n"
             "ldr r0, [%2, #0]\n"
             "str r0, [%0, #0]\n"
             "ldr r0, [%2, #4]\n"
             "str r0, [%0, #4]\n"
             "add %0, %0, %1\n"
             "add %2, %2, %1\n"
             "subs %3, %3, #2\n"
             "bne yLoop2\n"          

            : /* no output registers */
            : "r" (dst), "r" (dstPitch), "r" (src), "r" (height)
            : "r0", "%0", "%2", "%3");
}

}

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