1 files changed, 112 insertions, 0 deletions
diff --git a/src/libs/graphics/sdl/bilinear2x.c b/src/libs/graphics/sdl/bilinear2x.c
new file mode 100644
index 0000000..a12eb93
--- /dev/null
+++ b/src/libs/graphics/sdl/bilinear2x.c
@@ -0,0 +1,112 @@
+/*
+ *  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 BiLinear screen scaler
+//  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"
+
+
+// Bilinear scaling to 2x
+// The name expands to either
+//		Scale_BilinearFilter (for plain C) or
+//		Scale_MMX_BilinearFilter (for MMX)
+//		Scale_SSE_BilinearFilter (for SSE)
+//		[others when platforms are added]
+void
+SCALE_(BilinearFilter) (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 pitch = src->pitch, dp = dst->pitch;
+	const int bpp = fmt->BytesPerPixel;
+	const int len = pitch / bpp, dlen = dp / bpp;
+	Uint32 p[4];	// influential pixels array
+	Uint32 *srow0 = (Uint32 *) src->pixels;
+	Uint32 *dst_p = (Uint32 *) dst->pixels;
+
+	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 = w;
+	limits.h = h;
+	Scale_ExpandRect (region, 1, &limits);
+
+	xend = region->x + region->w;
+	yend = region->y + region->h;
+	dsrc = len - region->w;
+	ddst = (dlen - region->w) * 2;
+
+	// move ptrs to the first updated pixel
+	srow0 += len * region->y + region->x;
+	dst_p += (dlen * region->y + region->x) * 2;
+
+	for (y = region->y; y < yend; ++y, dst_p += ddst, srow0 += dsrc)
+	{
+		Uint32 *srow1;
+		
+		SCALE_(Prefetch) (srow0 + 16);
+		SCALE_(Prefetch) (srow0 + 32);
+		
+		if (y < h - 1)
+			srow1 = srow0 + len;
+		else
+			srow1 = srow0;
+
+		SCALE_(Prefetch) (srow1 + 16);
+		SCALE_(Prefetch) (srow1 + 32);
+
+		for (x = region->x; x < xend; ++x, ++srow0, ++srow1, dst_p += 2)
+		{
+			if (x < w - 1)
+			{	// can blend directly from pixels
+				SCALE_BILINEAR_BLEND4 (srow0, srow1, dst_p, dlen);
+			}
+			else
+			{	// need to make temp pixel rows
+				p[0] = srow0[0];
+				p[1] = p[0];
+				p[2] = srow1[0];
+				p[3] = p[2];
+
+				SCALE_BILINEAR_BLEND4 (&p[0], &p[2], dst_p, dlen);
+			}
+		}
+
+		SCALE_(Prefetch) (srow0 + dsrc);
+		SCALE_(Prefetch) (srow0 + dsrc + 16);
+		SCALE_(Prefetch) (srow1 + dsrc);
+		SCALE_(Prefetch) (srow1 + dsrc + 16);
+	}
+
+	SCALE_(PlatDone) ();
+}
+