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/* displaymodes.cpp
*
* Copyright (C) 2012 GBAtemp user Nebuleon.
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdio.h>
#include "ds2_types.h"
#include "ds2io.h"
#include "gfx.h"
static uint16 SevenToSixScanlineResize (uint16 TopColour, uint16 BottomColour, uint8 TopFraction, uint8 BottomFraction)
{
// Speed hacks!
if (TopColour == BottomColour) // Two colours identical (no calc)
return TopColour;
if (TopColour == 0x0000) // From black to a non-identical colour
return
// Red component
( ( ((BottomColour >> 10) & 0x1F) * BottomFraction / 7 ) << 10 )
// Green component
| ( ( ((BottomColour >> 5) & 0x1F) * BottomFraction / 7 ) << 5 )
// Blue component
| ( ( (BottomColour & 0x1F) * BottomFraction / 7 ) )
;
if (BottomColour == 0x0000) // To black from a non-identical colour
return
// Red component
( ( ((TopColour >> 10) & 0x1F) * TopFraction / 7 ) << 10 )
// Green component
| ( ( ((TopColour >> 5) & 0x1F) * TopFraction / 7 ) << 5 )
// Blue component
| ( ( (TopColour & 0x1F) * TopFraction / 7 ) )
;
return
// Red component
( ( ((TopColour >> 10) & 0x1F) * TopFraction / 7 + ((BottomColour >> 10) & 0x1F) * BottomFraction / 7 ) << 10 )
// Green component
| ( ( ((TopColour >> 5) & 0x1F) * TopFraction / 7 + ((BottomColour >> 5) & 0x1F) * BottomFraction / 7 ) << 5 )
// Blue component
| ( ( (TopColour & 0x1F) * TopFraction / 7 + (BottomColour & 0x1F) * BottomFraction / 7 ) )
;
}
void NDSSFCDrawFrameAntialiased (void* screen_addr)
{
uint16 X, Y;
uint16 *SrcTop = (uint16 *) GFX.Screen, *SrcBottom = SrcTop + 256, *Dest = (uint16 *) screen_addr;
for (Y = 0; Y < 224; Y += 7)
{
for (X = 0; X < 256; X++)
*Dest++ = SevenToSixScanlineResize (*SrcTop++, *SrcBottom++, 6, 1);
// At the end of this loop, line 1 for this block of 6
// has been drawn from the 2 first lines in the block
// of 7. Do the rest.
for (X = 0; X < 256; X++)
*Dest++ = SevenToSixScanlineResize (*SrcTop++, *SrcBottom++, 5, 2);
for (X = 0; X < 256; X++)
*Dest++ = SevenToSixScanlineResize (*SrcTop++, *SrcBottom++, 4, 3);
for (X = 0; X < 256; X++)
*Dest++ = SevenToSixScanlineResize (*SrcTop++, *SrcBottom++, 3, 4);
for (X = 0; X < 256; X++)
*Dest++ = SevenToSixScanlineResize (*SrcTop++, *SrcBottom++, 2, 5);
for (X = 0; X < 256; X++)
*Dest++ = SevenToSixScanlineResize (*SrcTop++, *SrcBottom++, 1, 6);
// At the end of these loops, SrcTop and SrcBottom point to
// the first element in the 7th line of the current block and
// the first element in the 1st line of the next.
// We need to increase the pointer to start on lines 1 & 2.
SrcTop += 256;
SrcBottom += 256;
}
}
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