mss1: move code that will be reused by MSS2 decoder into separate file

libavcodec/mss12.h

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2012 Konstantin Shishkov
+ *
+ * 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
+ * Common header for Microsoft Screen 1 and 2
+ */
+
+#ifndef AVCODEC_MSS12_H
+#define AVCODEC_MSS12_H
+
+#include "avcodec.h"
+#include "get_bits.h"
+
+#define MODEL_MIN_SYMS    2
+#define MODEL_MAX_SYMS  256
+#define THRESH_ADAPTIVE  -1
+#define THRESH_LOW       15
+#define THRESH_HIGH      50
+
+typedef struct Model {
+    int cum_prob[MODEL_MAX_SYMS + 1];
+    int weights[MODEL_MAX_SYMS + 1];
+    int idx2sym[MODEL_MAX_SYMS + 1];
+    int sym2idx[MODEL_MAX_SYMS + 1];
+    int num_syms;
+    int thr_weight, threshold;
+} Model;
+
+typedef struct ArithCoder {
+    int low, high, value;
+    GetBitContext *gb;
+    int (*get_model_sym)(struct ArithCoder *c, Model *m);
+    int (*get_number)   (struct ArithCoder *c, int n);
+} ArithCoder;
+
+typedef struct PixContext {
+    int cache_size, num_syms;
+    uint8_t cache[12];
+    Model cache_model, full_model;
+    Model sec_models[4][8][4];
+} PixContext;
+
+typedef struct MSS12Context {
+    AVCodecContext *avctx;
+    uint8_t        *pic_start;
+    int            pic_stride;
+    uint8_t        *mask;
+    int            mask_linesize;
+    uint32_t       pal[256];
+    int            free_colours;
+    int            keyframe;
+    Model          intra_region, inter_region;
+    Model          pivot, edge_mode, split_mode;
+    PixContext     intra_pix_ctx, inter_pix_ctx;
+    int            corrupted;
+} MSS12Context;
+
+int ff_mss12_decode_rect(MSS12Context *ctx, ArithCoder *acoder,
+                         int x, int y, int width, int height);
+void ff_mss12_model_update(Model *m, int val);
+void ff_mss12_codec_reset(MSS12Context *ctx);
+av_cold int ff_mss12_decode_init(AVCodecContext *avctx, int version);
+av_cold int ff_mss12_decode_end(AVCodecContext *avctx);
+
+#endif /* AVCODEC_MSS12_H */