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diff --git a/libavcodec/elsdec.h b/libavcodec/elsdec.h
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+/*
+ * ELS (Entropy Logarithmic-Scale) decoder
+ *
+ * Copyright (c) 2013 Maxim Poliakovski
+ *
+ * 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
+ */
+
+/**
+ * @file
+ * Entropy Logarithmic-Scale binary arithmetic coder
+ */
+
+#ifndef AVCODEC_ELSDEC_H
+#define AVCODEC_ELSDEC_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#define ELS_EXPGOLOMB_LEN 10
+
+typedef struct ElsDecCtx {
+ const uint8_t *in_buf;
+ unsigned x;
+ size_t data_size;
+ int j, t, diff, err;
+} ElsDecCtx;
+
+typedef struct ElsRungNode {
+ uint8_t rung;
+ uint16_t next_index;
+} ElsRungNode;
+
+typedef struct ElsUnsignedRung {
+ uint8_t prefix_rung[ELS_EXPGOLOMB_LEN + 1];
+ ElsRungNode *rem_rung_list;
+ size_t rung_list_size;
+ uint16_t avail_index;
+} ElsUnsignedRung;
+
+void ff_els_decoder_init(ElsDecCtx *ctx, const uint8_t *in, size_t data_size);
+void ff_els_decoder_uninit(ElsUnsignedRung *rung);
+int ff_els_decode_bit(ElsDecCtx *ctx, unsigned char *rung);
+unsigned ff_els_decode_unsigned(ElsDecCtx *ctx, ElsUnsignedRung *ur);
+
+#endif /* AVCODEC_ELSDEC_H */