avcodec/scpr: add version 3 support

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/scpr3.h

+/*
+ * ScreenPressor version 3 decoder
+ *
+ * Copyright (c) 2017 Paul B Mahol
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVCODEC_SCPR3_H
+#define AVCODEC_SCPR3_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "avcodec.h"
+#include "internal.h"
+
+typedef struct PixelModel3 {
+    uint8_t    type;
+    uint8_t    length;
+    uint8_t    maxpos;
+    uint8_t    fshift;
+    uint16_t   size;
+    uint32_t   cntsum;
+    uint8_t    symbols[256];
+    uint16_t   freqs[256];
+    uint16_t   freqs1[256];
+    uint16_t   cnts[256];
+    uint8_t    dectab[32];
+} PixelModel3;
+
+typedef struct FillModel3 {
+    uint32_t   cntsum;
+    uint16_t   freqs[2][5];
+    uint16_t   cnts[5];
+    uint8_t    dectab[32];
+} FillModel3;
+
+typedef struct OpModel3 {
+    uint32_t   cntsum;
+    uint16_t   freqs[2][6];
+    uint16_t   cnts[6];
+    uint8_t    dectab[32];
+} OpModel3;
+
+typedef struct RunModel3 {
+    uint32_t   cntsum;
+    uint16_t   freqs[2][256];
+    uint16_t   cnts[256];
+    uint8_t    dectab[32];
+} RunModel3;
+
+typedef struct SxyModel3 {
+    uint32_t   cntsum;
+    uint16_t   freqs[2][16];
+    uint16_t   cnts[16];
+    uint8_t    dectab[32];
+} SxyModel3;
+
+typedef struct MVModel3 {
+    uint32_t   cntsum;
+    uint16_t   freqs[2][512];
+    uint16_t   cnts[512];
+    uint8_t    dectab[32];
+} MVModel3;
+
+#endif /* AVCODEC_SCPR3_H */