lavc/golomb: unmerge the cached bitstream reader codebitstream_unmerge

Move the cached bitstream reader code to a new header, which can either
be used on its own with the cached bitstream reader, or from get_bits
code by #defining CACHED_BITSTREAM_READER.

Restore proper attribution for this code.

Integration by Anton Khirnov <anton@khirnov.net>

3 files changed, 376 insertions, 162 deletions

diff --git a/libavcodec/golomb.h b/libavcodec/golomb.h
index 164c2583b6..905da4f51c 100644
--- a/libavcodec/golomb.h
+++ b/libavcodec/golomb.h
@@ -33,17 +33,30 @@
 #include <stdint.h>
 
 #include "get_bits.h"
+#include "golomb_common.h"
 
-#define INVALID_VLC           0x80000000
+#if CACHED_BITSTREAM_READER
 
-extern const uint8_t ff_golomb_vlc_len[512];
-extern const uint8_t ff_ue_golomb_vlc_code[512];
-extern const  int8_t ff_se_golomb_vlc_code[512];
+#include "golomb_bs.h"
+
+#define get_ue_golomb               golomb_bs_get_ue
+#define get_ue_golomb_long          golomb_bs_get_ue_long
+#define get_ue_golomb_31            golomb_bs_get_ue_31
+#define get_interleaved_ue_golomb   golomb_bs_get_ue_interleaved
+#define get_te0_golomb              golomb_bs_get_te0
+#define get_te_golomb               golomb_bs_get_te
+#define get_se_golomb               golomb_bs_get_se
+#define get_se_golomb_long          golomb_bs_get_se_long
+#define get_interleaved_se_golomb   golomb_bs_get_se_interleaved
+#define dirac_get_se_golomb         golomb_bs_get_se_dirac
+#define get_ur_golomb               golomb_bs_get_ur
+#define get_ur_golomb_jpegls        golomb_bs_get_ur_jpegls
+#define get_sr_golomb               golomb_bs_get_sr
+#define get_sr_golomb_flac          golomb_bs_get_sr_flac
+#define get_ur_golomb_shorten       golomb_bs_get_ur_shorten
+#define get_sr_golomb_shorten       golomb_bs_get_sr_shorten
 
-extern const uint8_t ff_interleaved_golomb_vlc_len[256];
-extern const uint8_t ff_interleaved_ue_golomb_vlc_code[256];
-extern const  int8_t ff_interleaved_se_golomb_vlc_code[256];
-extern const uint8_t ff_interleaved_dirac_golomb_vlc_code[256];
+#else
 
 /**
  * Read an unsigned Exp-Golomb code in the range 0 to 8190.
@@ -54,26 +67,6 @@ static inline int get_ue_golomb(GetBitContext *gb)
 {
     unsigned int buf;
 
-#if CACHED_BITSTREAM_READER
-    buf = show_bits_long(gb, 32);
-
-    if (buf >= (1 << 27)) {
-        buf >>= 32 - 9;
-        skip_bits_long(gb, ff_golomb_vlc_len[buf]);
-
-        return ff_ue_golomb_vlc_code[buf];
-    } else {
-        int log = 2 * av_log2(buf) - 31;
-
-        skip_bits_long(gb, 32 - log);
-        if (log < 7)
-            return AVERROR_INVALIDDATA;
-        buf >>= log;
-        buf--;
-
-        return buf;
-    }
-#else
     OPEN_READER(re, gb);
     UPDATE_CACHE(re, gb);
     buf = GET_CACHE(re, gb);
@@ -95,7 +88,6 @@ static inline int get_ue_golomb(GetBitContext *gb)
 
         return buf;
     }
-#endif
 }
 
 /**
@@ -121,13 +113,6 @@ static inline int get_ue_golomb_31(GetBitContext *gb)
 {
     unsigned int buf;
 
-#if CACHED_BITSTREAM_READER
-    buf = show_bits_long(gb, 32);
-
-    buf >>= 32 - 9;
-    skip_bits_long(gb, ff_golomb_vlc_len[buf]);
-#else
-
     OPEN_READER(re, gb);
     UPDATE_CACHE(re, gb);
     buf = GET_CACHE(re, gb);
@@ -135,7 +120,6 @@ static inline int get_ue_golomb_31(GetBitContext *gb)
     buf >>= 32 - 9;
     LAST_SKIP_BITS(re, gb, ff_golomb_vlc_len[buf]);
     CLOSE_READER(re, gb);
-#endif
 
     return ff_ue_golomb_vlc_code[buf];
 }
@@ -144,33 +128,6 @@ static inline unsigned get_interleaved_ue_golomb(GetBitContext *gb)
 {
     uint32_t buf;
 
-#if CACHED_BITSTREAM_READER
-    buf = show_bits_long(gb, 32);
-
-    if (buf & 0xAA800000) {
-        buf >>= 32 - 8;
-        skip_bits_long(gb, ff_interleaved_golomb_vlc_len[buf]);
-
-        return ff_interleaved_ue_golomb_vlc_code[buf];
-    } else {
-        unsigned ret = 1;
-
-        do {
-            buf >>= 32 - 8;
-            skip_bits_long(gb, FFMIN(ff_interleaved_golomb_vlc_len[buf], 8));
-
-            if (ff_interleaved_golomb_vlc_len[buf] != 9) {
-                ret <<= (ff_interleaved_golomb_vlc_len[buf] - 1) >> 1;
-                ret  |= ff_interleaved_dirac_golomb_vlc_code[buf];
-                break;
-            }
-            ret = (ret << 4) | ff_interleaved_dirac_golomb_vlc_code[buf];
-            buf = show_bits_long(gb, 32);
-        } while (get_bits_left(gb) > 0);
-
-        return ret - 1;
-    }
-#else
     OPEN_READER(re, gb);
     UPDATE_CACHE(re, gb);
     buf = GET_CACHE(re, gb);
@@ -202,7 +159,6 @@ static inline unsigned get_interleaved_ue_golomb(GetBitContext *gb)
         CLOSE_READER(re, gb);
         return ret - 1;
     }
-#endif
 }
 
 /**
@@ -240,28 +196,6 @@ static inline int get_se_golomb(GetBitContext *gb)
 {
     unsigned int buf;
 
-#if CACHED_BITSTREAM_READER
-    buf = show_bits_long(gb, 32);
-
-    if (buf >= (1 << 27)) {
-        buf >>= 32 - 9;
-        skip_bits_long(gb, ff_golomb_vlc_len[buf]);
-
-        return ff_se_golomb_vlc_code[buf];
-    } else {
-        int log = 2 * av_log2(buf) - 31;
-        buf >>= log;
-
-        skip_bits_long(gb, 32 - log);
-
-        if (buf & 1)
-            buf = -(buf >> 1);
-        else
-            buf = (buf >> 1);
-
-        return buf;
-    }
-#else
     OPEN_READER(re, gb);
     UPDATE_CACHE(re, gb);
     buf = GET_CACHE(re, gb);
@@ -288,7 +222,6 @@ static inline int get_se_golomb(GetBitContext *gb)
 
         return buf;
     }
-#endif
 }
 
 static inline int get_se_golomb_long(GetBitContext *gb)
@@ -302,30 +235,6 @@ static inline int get_interleaved_se_golomb(GetBitContext *gb)
 {
     unsigned int buf;
 
-#if CACHED_BITSTREAM_READER
-    buf = show_bits_long(gb, 32);
-
-    if (buf & 0xAA800000) {
-        buf >>= 32 - 8;
-        skip_bits_long(gb, ff_interleaved_golomb_vlc_len[buf]);
-
-        return ff_interleaved_se_golomb_vlc_code[buf];
-    } else {
-        int log;
-        skip_bits(gb, 8);
-        buf |= 1 | show_bits(gb, 24);
-
-        if ((buf & 0xAAAAAAAA) == 0)
-            return INVALID_VLC;
-
-        for (log = 31; (buf & 0x80000000) == 0; log--)
-            buf = (buf << 2) - ((buf << log) >> (log - 1)) + (buf >> 30);
-
-        skip_bits_long(gb, 63 - 2 * log - 8);
-
-        return (signed) (((((buf << log) >> log) - 1) ^ -(buf & 0x1)) + 1) >> 1;
-    }
-#else
     OPEN_READER(re, gb);
     UPDATE_CACHE(re, gb);
     buf = GET_CACHE(re, gb);
@@ -353,7 +262,6 @@ static inline int get_interleaved_se_golomb(GetBitContext *gb)
 
         return (signed) (((((buf << log) >> log) - 1) ^ -(buf & 0x1)) + 1) >> 1;
     }
-#endif
 }
 
 static inline int dirac_get_se_golomb(GetBitContext *gb)
@@ -377,24 +285,6 @@ static inline int get_ur_golomb(GetBitContext *gb, int k, int limit,
     unsigned int buf;
     int log;
 
-#if CACHED_BITSTREAM_READER
-    buf = show_bits_long(gb, 32);
-
-    log = av_log2(buf);
-
-    if (log > 31 - limit) {
-        buf >>= log - k;
-        buf  += (30 - log) << k;
-        skip_bits_long(gb, 32 + k - log);
-
-        return buf;
-    } else {
-        skip_bits_long(gb, limit);
-        buf = get_bits_long(gb, esc_len);
-
-        return buf + limit - 1;
-    }
-#else
     OPEN_READER(re, gb);
     UPDATE_CACHE(re, gb);
     buf = GET_CACHE(re, gb);
@@ -419,7 +309,6 @@ static inline int get_ur_golomb(GetBitContext *gb, int k, int limit,
 
         return buf + limit - 1;
     }
-#endif
 }
 
 /**
@@ -431,35 +320,6 @@ static inline int get_ur_golomb_jpegls(GetBitContext *gb, int k, int limit,
     unsigned int buf;
     int log;
 
-#if CACHED_BITSTREAM_READER
-    buf = show_bits_long(gb, 32);
-
-    log = av_log2(buf);
-
-    if (log - k >= 1 && 32 - log < limit) {
-        buf >>= log - k;
-        buf  += (30 - log) << k;
-        skip_bits_long(gb, 32 + k - log);
-
-        return buf;
-    } else {
-        int i;
-        for (i = 0;
-             i < limit && get_bits1(gb) == 0 && get_bits_left(gb) > 0;
-             i++);
-
-        if (i < limit - 1) {
-            buf = get_bits_long(gb, k);
-
-            return buf + (i << k);
-        } else if (i == limit - 1) {
-            buf = get_bits_long(gb, esc_len);
-
-            return buf + 1;
-        } else
-            return -1;
-    }
-#else
     OPEN_READER(re, gb);
     UPDATE_CACHE(re, gb);
     buf = GET_CACHE(re, gb);
@@ -520,7 +380,6 @@ static inline int get_ur_golomb_jpegls(GetBitContext *gb, int k, int limit,
         CLOSE_READER(re, gb);
         return buf;
     }
-#endif
 }
 
 /**
@@ -613,4 +472,7 @@ static inline int get_te(GetBitContext *s, int r, char *file, const char *func,
 #define get_te0_golomb(a, r) get_te(a, r, __FILE__, __func__, __LINE__)
 
 #endif /* TRACE */
+
+#endif /* CACHED_BITSTREAM_READER */
+
 #endif /* AVCODEC_GOLOMB_H */
diff --git a/libavcodec/golomb_bs.h b/libavcodec/golomb_bs.h
new file mode 100644
index 0000000000..bba126bfc4
--- /dev/null
+++ b/libavcodec/golomb_bs.h
@@ -0,0 +1,317 @@
+/*
+ * 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_GOLOMB_BS_H
+#define AVCODEC_GOLOMB_BS_H
+
+#include <stdint.h>
+
+#include "bitstream.h"
+#include "golomb_common.h"
+
+/**
+ * Read an unsigned Exp-Golomb code in the range 0 to 8190.
+ *
+ * @returns the read value or a negative error code.
+ */
+static inline int golomb_bs_get_ue(BitstreamContext *bc)
+{
+    unsigned int buf = bitstream_peek(bc, 32);
+
+    if (buf >= (1 << 27)) {
+        buf >>= 32 - 9;
+        bitstream_skip_cache(bc, ff_golomb_vlc_len[buf]);
+
+        return ff_ue_golomb_vlc_code[buf];
+    } else {
+        int log = 2 * av_log2(buf) - 31;
+
+        bitstream_skip_cache(bc, 32 - log);
+        if (log < 7)
+            return AVERROR_INVALIDDATA;
+        buf >>= log;
+        buf--;
+
+        return buf;
+    }
+}
+
+/**
+ * Read an unsigned Exp-Golomb code in the range 0 to UINT32_MAX-1.
+ */
+static inline unsigned golomb_bs_get_ue_long(BitstreamContext *bc)
+{
+    unsigned int buf = bitstream_peek(bc, 32);
+    unsigned int log = 31 - av_log2(buf);
+    bitstream_skip_cache(bc, log);
+    return bitstream_read(bc, log + 1) - 1;
+}
+
+/**
+ * read unsigned exp golomb code, constraint to a max of 31.
+ * If the value encountered is not in 0..31, the return value
+ * is outside the range 0..30.
+ */
+static inline int golomb_bs_get_ue_31(BitstreamContext *bc)
+{
+    unsigned int buf = bitstream_peek(bc, 32);
+
+    buf >>= 32 - 9;
+    bitstream_skip_cache(bc, ff_golomb_vlc_len[buf]);
+
+    return ff_ue_golomb_vlc_code[buf];
+}
+
+static inline unsigned golomb_bs_get_ue_interleaved(BitstreamContext *bc)
+{
+    uint32_t buf = bitstream_peek(bc, 32);
+
+    if (buf & 0xAA800000) {
+        buf >>= 32 - 8;
+        bitstream_skip_cache(bc, ff_interleaved_golomb_vlc_len[buf]);
+
+        return ff_interleaved_ue_golomb_vlc_code[buf];
+    } else {
+        unsigned ret = 1;
+
+        do {
+            buf >>= 32 - 8;
+            bitstream_skip_cache(bc, FFMIN(ff_interleaved_golomb_vlc_len[buf], 8));
+
+            if (ff_interleaved_golomb_vlc_len[buf] != 9) {
+                ret <<= (ff_interleaved_golomb_vlc_len[buf] - 1) >> 1;
+                ret  |= ff_interleaved_dirac_golomb_vlc_code[buf];
+                break;
+            }
+            ret = (ret << 4) | ff_interleaved_dirac_golomb_vlc_code[buf];
+            buf = bitstream_peek(bc, 32);
+        } while (bitstream_bits_left(bc) > 0);
+
+        return ret - 1;
+    }
+}
+
+/**
+ * read unsigned truncated exp golomb code.
+ */
+static inline int golomb_bs_get_te0(BitstreamContext *bc, int range)
+{
+    av_assert2(range >= 1);
+
+    if (range == 1)
+        return 0;
+    else if (range == 2)
+        return bitstream_read(bc, 1) ^ 1;
+    else
+        return golomb_bs_get_ue(bc);
+}
+
+/**
+ * read unsigned truncated exp golomb code.
+ */
+static inline int golomb_bs_get_te(BitstreamContext *bc, int range)
+{
+    av_assert2(range >= 1);
+
+    if (range == 2)
+        return bitstream_read(bc, 1) ^ 1;
+    else
+        return golomb_bs_get_ue(bc);
+}
+
+/**
+ * read signed exp golomb code.
+ */
+static inline int golomb_bs_get_se(BitstreamContext *bc)
+{
+    unsigned int buf;
+
+    buf = bitstream_peek(bc, 32);
+
+    if (buf >= (1 << 27)) {
+        buf >>= 32 - 9;
+        bitstream_skip_cache(bc, ff_golomb_vlc_len[buf]);
+
+        return ff_se_golomb_vlc_code[buf];
+    } else {
+        int log = 2 * av_log2(buf) - 31;
+        buf >>= log;
+
+        bitstream_skip_cache(bc, 32 - log);
+
+        if (buf & 1)
+            buf = -(buf >> 1);
+        else
+            buf = (buf >> 1);
+
+        return buf;
+    }
+}
+
+static inline int golomb_bs_get_se_long(BitstreamContext *bc)
+{
+    unsigned int buf = golomb_bs_get_ue_long(bc);
+    int sign = (buf & 1) - 1;
+    return ((buf >> 1) ^ sign) + 1;
+}
+
+static inline int golomb_bs_get_se_interleaved(BitstreamContext *bc)
+{
+    unsigned int buf;
+
+    buf = bitstream_peek(bc, 32);
+
+    if (buf & 0xAA800000) {
+        buf >>= 32 - 8;
+        bitstream_skip_cache(bc, ff_interleaved_golomb_vlc_len[buf]);
+
+        return ff_interleaved_se_golomb_vlc_code[buf];
+    } else {
+        int log;
+        bitstream_skip_cache(bc, 8);
+        buf |= 1 | bitstream_peek(bc, 24);
+
+        if ((buf & 0xAAAAAAAA) == 0)
+            return INVALID_VLC;
+
+        for (log = 31; (buf & 0x80000000) == 0; log--)
+            buf = (buf << 2) - ((buf << log) >> (log - 1)) + (buf >> 30);
+
+        bitstream_skip(bc, 63 - 2 * log - 8);
+
+        return (signed) (((((buf << log) >> log) - 1) ^ -(buf & 0x1)) + 1) >> 1;
+    }
+}
+
+static inline int golomb_bs_get_se_dirac(BitstreamContext *bc)
+{
+    uint32_t ret = golomb_bs_get_ue_interleaved(bc);
+
+    if (ret) {
+        int sign = -bitstream_read(bc, 1);
+        ret = (ret ^ sign) - sign;
+    }
+
+    return ret;
+}
+
+/**
+ * read unsigned golomb rice code (ffv1).
+ */
+static inline int golomb_bs_get_ur(BitstreamContext *bc, int k, int limit,
+                                   int esc_len)
+{
+    unsigned int buf;
+    int log;
+
+    buf = bitstream_peek(bc, 32);
+
+    log = av_log2(buf);
+
+    if (log > 31 - limit) {
+        buf >>= log - k;
+        buf  += (30 - log) << k;
+        bitstream_skip(bc, 32 + k - log);
+
+        return buf;
+    } else {
+        bitstream_skip(bc, limit);
+        buf = bitstream_read(bc, esc_len);
+
+        return buf + limit - 1;
+    }
+}
+
+/**
+ * read unsigned golomb rice code (jpegls).
+ */
+static inline int golomb_bs_get_ur_jpegls(BitstreamContext *bc, int k, int limit,
+                                          int esc_len)
+{
+    unsigned int buf;
+    int log;
+
+    buf = bitstream_peek(bc, 32);
+
+    log = av_log2(buf);
+
+    if (log - k >= 1 && 32 - log < limit) {
+        buf >>= log - k;
+        buf  += (30 - log) << k;
+        bitstream_skip(bc, 32 + k - log);
+
+        return buf;
+    } else {
+        int i;
+        for (i = 0;
+             i < limit && bitstream_peek(bc, 1) == 0 && bitstream_bits_left(bc) > 0;
+             i++)
+            bitstream_skip_cache(bc, 1);
+        bitstream_skip(bc, 1);
+
+        if (i < limit - 1) {
+            buf = bitstream_read(bc, k);
+
+            return buf + (i << k);
+        } else if (i == limit - 1) {
+            buf = bitstream_read(bc, esc_len);
+
+            return buf + 1;
+        } else
+            return -1;
+    }
+}
+
+/**
+ * read signed golomb rice code (ffv1).
+ */
+static inline int golomb_bs_get_sr(BitstreamContext *bc, int k, int limit,
+                                   int esc_len)
+{
+    unsigned v = golomb_bs_get_ur(bc, k, limit, esc_len);
+    return (v >> 1) ^ -(v & 1);
+}
+
+/**
+ * read signed golomb rice code (flac).
+ */
+static inline int golomb_bs_get_sr_flac(BitstreamContext *bc, int k, int limit,
+                                        int esc_len)
+{
+    unsigned v = golomb_bs_get_ur_jpegls(bc, k, limit, esc_len);
+    return (v >> 1) ^ -(v & 1);
+}
+
+/**
+ * read unsigned golomb rice code (shorten).
+ */
+static inline unsigned int golomb_bs_get_ur_shorten(BitstreamContext *bc, int k)
+{
+    return golomb_bs_get_ur_jpegls(bc, k, INT_MAX, 0);
+}
+
+/**
+ * read signed golomb rice code (shorten).
+ */
+static inline int golomb_bs_get_sr_shorten(BitstreamContext *bc, int k)
+{
+    int uvar = golomb_bs_get_ur_jpegls(bc, k + 1, INT_MAX, 0);
+    return (uvar >> 1) ^ -(uvar & 1);
+}
+
+#endif /* AVCODEC_GOLOMB_BS_H */
diff --git a/libavcodec/golomb_common.h b/libavcodec/golomb_common.h
new file mode 100644
index 0000000000..19136aae3c
--- /dev/null
+++ b/libavcodec/golomb_common.h
@@ -0,0 +1,35 @@
+/*
+ * 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_GOLOMB_COMMON_H
+#define AVCODEC_GOLOMB_COMMON_H
+
+#include <stdint.h>
+
+#define INVALID_VLC           0x80000000
+
+extern const uint8_t ff_golomb_vlc_len[512];
+extern const uint8_t ff_ue_golomb_vlc_code[512];
+extern const  int8_t ff_se_golomb_vlc_code[512];
+
+extern const uint8_t ff_interleaved_golomb_vlc_len[256];
+extern const uint8_t ff_interleaved_ue_golomb_vlc_code[256];
+extern const  int8_t ff_interleaved_se_golomb_vlc_code[256];
+extern const uint8_t ff_interleaved_dirac_golomb_vlc_code[256];
+
+#endif /* AVCODEC_GOLOMB_COMMON_H */