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/*
* 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.
*/
// Core algorithm of the Triscan screen scaler (based on Scale2x)
// (for scale2x please see http://scale2x.sf.net)
// Template
// When this file is built standalone is produces a plain C version
// Also #included by 2xscalers_mmx.c for an MMX version
#include "libs/graphics/sdl/sdl_common.h"
#include "types.h"
#include "scalers.h"
#include "scaleint.h"
#include "2xscalers.h"
// Triscan scaling to 2x
// derivative of scale2x -- scale2x.sf.net
// The name expands to either
// Scale_TriScanFilter (for plain C) or
// Scale_MMX_TriScanFilter (for MMX)
// [others when platforms are added]
void
SCALE_(TriScanFilter) (SDL_Surface *src, SDL_Surface *dst, SDL_Rect *r)
{
int x, y;
const int w = src->w, h = src->h;
int xend, yend;
int dsrc, ddst;
SDL_Rect *region = r;
SDL_Rect limits;
SDL_PixelFormat *fmt = dst->format;
const int sp = src->pitch, dp = dst->pitch;
const int bpp = fmt->BytesPerPixel;
const int slen = sp / bpp, dlen = dp / bpp;
// for clarity purposes, the 'pixels' array here is transposed
Uint32 pixels[3][3];
Uint32 *src_p = (Uint32 *)src->pixels;
Uint32 *dst_p = (Uint32 *)dst->pixels;
int prevline, nextline;
// these macros are for clarity; they make the current pixel (0,0)
// and allow to access pixels in all directions
#define PIX(x, y) (pixels[1 + (x)][1 + (y)])
#define TRISCAN_YUV_MED 100
// medium tolerance pixel comparison
#define TRISCAN_CMPYUV(p1, p2) \
(PIX p1 == PIX p2 || SCALE_CMPYUV (PIX p1, PIX p2, TRISCAN_YUV_MED))
SCALE_(PlatInit) ();
// expand updated region if necessary
// pixels neighbooring the updated region may
// change as a result of updates
limits.x = 0;
limits.y = 0;
limits.w = src->w;
limits.h = src->h;
Scale_ExpandRect (region, 1, &limits);
xend = region->x + region->w;
yend = region->y + region->h;
dsrc = slen - region->w;
ddst = (dlen - region->w) * 2;
// move ptrs to the first updated pixel
src_p += slen * region->y + region->x;
dst_p += (dlen * region->y + region->x) * 2;
for (y = region->y; y < yend; ++y, dst_p += ddst, src_p += dsrc)
{
if (y > 0)
prevline = -slen;
else
prevline = 0;
if (y < h - 1)
nextline = slen;
else
nextline = 0;
// prime the (tiny) sliding-window pixel arrays
PIX( 1, 0) = src_p[0];
if (region->x > 0)
PIX( 0, 0) = src_p[-1];
else
PIX( 0, 0) = PIX( 1, 0);
for (x = region->x; x < xend; ++x, ++src_p, dst_p += 2)
{
// slide the window
PIX(-1, 0) = PIX( 0, 0);
PIX( 0, -1) = src_p[prevline];
PIX( 0, 0) = PIX( 1, 0);
PIX( 0, 1) = src_p[nextline];
if (x < w - 1)
PIX( 1, 0) = src_p[1];
else
PIX( 1, 0) = PIX( 0, 0);
if (!TRISCAN_CMPYUV (( 0, -1), ( 0, 1)) &&
!TRISCAN_CMPYUV ((-1, 0), ( 1, 0)))
{
if (TRISCAN_CMPYUV ((-1, 0), ( 0, -1)))
dst_p[0] = Scale_Blend_11 (PIX(-1, 0), PIX(0, -1));
else
dst_p[0] = PIX(0, 0);
if (TRISCAN_CMPYUV (( 1, 0), ( 0, -1)))
dst_p[1] = Scale_Blend_11 (PIX(1, 0), PIX(0, -1));
else
dst_p[1] = PIX(0, 0);
if (TRISCAN_CMPYUV ((-1, 0), ( 0, 1)))
dst_p[dlen] = Scale_Blend_11 (PIX(-1, 0), PIX(0, 1));
else
dst_p[dlen] = PIX(0, 0);
if (TRISCAN_CMPYUV (( 1, 0), ( 0, 1)))
dst_p[dlen+1] = Scale_Blend_11 (PIX(1, 0), PIX(0, 1));
else
dst_p[dlen+1] = PIX(0, 0);
}
else
{
dst_p[0] = PIX(0, 0);
dst_p[1] = PIX(0, 0);
dst_p[dlen] = PIX(0, 0);
dst_p[dlen+1] = PIX(0, 0);
}
}
}
SCALE_(PlatDone) ();
}
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