lavc: introduce VideoDSPContext

Move some functions from dsputil. The idea is that videodsp contains
functions that are useful for a large and varied set of video decoders.
Currently, it contains emulated_edge_mc() and prefetch().

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavcodec/videodsp.h

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2012 Ronald S. Bultje
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * Core video DSP helper functions
+ */
+
+#ifndef AVCODEC_VIDEODSP_H
+#define AVCODEC_VIDEODSP_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+typedef struct VideoDSPContext {
+    /**
+     * Copy a rectangular area of samples to a temporary buffer and replicate
+     * the border samples.
+     *
+     * @param buf destination buffer
+     * @param src source buffer
+     * @param linesize number of bytes between 2 vertically adjacent samples
+     *                 in both the source and destination buffers
+     * @param block_w width of block
+     * @param block_h height of block
+     * @param src_x x coordinate of the top left sample of the block in the
+     *                source buffer
+     * @param src_y y coordinate of the top left sample of the block in the
+     *                source buffer
+     * @param w width of the source buffer
+     * @param h height of the source buffer
+     */
+    void (*emulated_edge_mc)(uint8_t *buf, const uint8_t *src,
+                             ptrdiff_t linesize, int block_w, int block_h,
+                             int src_x, int src_y, int w, int h);
+
+    /**
+     * Prefetch memory into cache (if supported by hardware).
+     *
+     * @buf pointer to buffer to prefetch memory from
+     * @stride distance between two lines of buf (in bytes)
+     * @h number of lines to prefetch
+     */
+    void (*prefetch)(uint8_t *buf, ptrdiff_t stride, int h);
+} VideoDSPContext;
+
+void ff_videodsp_init(VideoDSPContext *ctx, int bpc);
+
+/* for internal use only (i.e. called by ff_videodsp_init() */
+void ff_videodsp_init_arm(VideoDSPContext *ctx, int bpc);
+void ff_videodsp_init_ppc(VideoDSPContext *ctx, int bpc);
+void ff_videodsp_init_x86(VideoDSPContext *ctx, int bpc);
+
+#endif /* AVCODEC_VIDEODSP_H */