Move bitstream.[ch] to codecs/lib/ffmpeg_bitstream.[ch] to avoid duplicate copies across codecs.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@22337 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 1239 insertions, 0 deletions

diff --git a/apps/codecs/lib/ffmpeg_bitstream.c b/apps/codecs/lib/ffmpeg_bitstream.c
new file mode 100644
index 0000000..88e3cbf
--- /dev/null
+++ b/apps/codecs/lib/ffmpeg_bitstream.c
@@ -0,0 +1,276 @@
+/*
+ * Common bit i/o utils
+ * Copyright (c) 2000, 2001 Fabrice Bellard
+ * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
+ *
+ * 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
+ */
+
+#include "ffmpeg_bitstream.h"
+
+#ifdef ROCKBOX
+#undef DEBUGF
+#define DEBUGF(...)
+#endif
+
+const uint8_t ff_log2_run[32]={
+ 0, 0, 0, 0, 1, 1, 1, 1,
+ 2, 2, 2, 2, 3, 3, 3, 3,
+ 4, 4, 5, 5, 6, 6, 7, 7,
+ 8, 9,10,11,12,13,14,15
+};
+
+/**
+ * Same as av_mallocz_static(), but does a realloc.
+ *
+ * @param[in] ptr The block of memory to reallocate.
+ * @param[in] size The requested size.
+ * @return Block of memory of requested size.
+ * @deprecated. Code which uses ff_realloc_static is broken/misdesigned
+ * and should correctly use static arrays
+ */
+
+
+void ff_put_string(PutBitContext * pbc, const char *s, int put_zero)
+{
+    while(*s){
+        put_bits(pbc, 8, *s);
+        s++;
+    }
+    if(put_zero)
+        put_bits(pbc, 8, 0);
+}
+
+/* VLC decoding */
+
+//#define DEBUG_VLC
+
+#define GET_DATA(v, table, i, wrap, size) \
+{\
+    const uint8_t *ptr = (const uint8_t *)table + i * wrap;\
+    switch(size) {\
+    case 1:\
+        v = *(const uint8_t *)ptr;\
+        break;\
+    case 2:\
+        v = *(const uint16_t *)ptr;\
+        break;\
+    default:\
+        v = *(const uint32_t *)ptr;\
+        break;\
+    }\
+}
+
+
+static int alloc_table(VLC *vlc, int size, int use_static)
+{
+    int index;
+    index = vlc->table_size;
+    vlc->table_size += size;
+    if (vlc->table_size > vlc->table_allocated) {
+        if(use_static>1){
+            DEBUGF("init_vlc() used with too little memory : table_size > allocated_memory\n");
+        }
+
+        if (!vlc->table)
+            return -1;
+    }
+    return index;
+}
+
+static int build_table(VLC *vlc, int table_nb_bits,
+                       int nb_codes,
+                       const void *bits, int bits_wrap, int bits_size,
+                       const void *codes, int codes_wrap, int codes_size,
+                       const void *symbols, int symbols_wrap, int symbols_size,
+                       uint32_t code_prefix, int n_prefix, int flags)
+{
+    int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2, symbol;
+    uint32_t code;
+    VLC_TYPE (*table)[2];
+
+    table_size = 1 << table_nb_bits;
+    table_index = alloc_table(vlc, table_size, flags & (INIT_VLC_USE_STATIC|INIT_VLC_USE_NEW_STATIC));
+#ifdef DEBUG_VLC
+    DEBUGF("new table index=%d size=%d code_prefix=%x n=%d\n",
+           table_index, table_size, code_prefix, n_prefix);
+#endif
+    if (table_index < 0)
+        return -1;
+    table = &vlc->table[table_index];
+
+    for(i=0;i<table_size;i++) {
+        table[i][1] = 0; //bits
+        table[i][0] = -1; //codes
+    }
+
+    /* first pass: map codes and compute auxillary table sizes */
+    for(i=0;i<nb_codes;i++) {
+        GET_DATA(n, bits, i, bits_wrap, bits_size);
+        GET_DATA(code, codes, i, codes_wrap, codes_size);
+        /* we accept tables with holes */
+        if (n <= 0)
+            continue;
+        if (!symbols)
+            symbol = i;
+        else
+            GET_DATA(symbol, symbols, i, symbols_wrap, symbols_size);
+#if defined(DEBUG_VLC) && 0
+        DEBUGF("i=%d n=%d code=0x%x\n", i, n, code);
+#endif
+        /* if code matches the prefix, it is in the table */
+        n -= n_prefix;
+        if(flags & INIT_VLC_LE)
+            code_prefix2= code & (n_prefix>=32 ? (int)0xffffffff : (1 << n_prefix)-1);
+        else
+            code_prefix2= code >> n;
+        if (n > 0 && code_prefix2 == (int)code_prefix) {
+            if (n <= table_nb_bits) {
+                /* no need to add another table */
+                j = (code << (table_nb_bits - n)) & (table_size - 1);
+                nb = 1 << (table_nb_bits - n);
+                for(k=0;k<nb;k++) {
+                    if(flags & INIT_VLC_LE)
+                        j = (code >> n_prefix) + (k<<n);
+#ifdef DEBUG_VLC
+                    DEBUGF("%4x: code=%d n=%d\n",
+                           j, i, n);
+#endif
+                    if (table[j][1] /*bits*/ != 0) {
+                        DEBUGF("incorrect codes\n");
+                        return -1;
+                    }
+                    table[j][1] = n; //bits
+                    table[j][0] = symbol;
+                    j++;
+                }
+            } else {
+                n -= table_nb_bits;
+                j = (code >> ((flags & INIT_VLC_LE) ? n_prefix : n)) & ((1 << table_nb_bits) - 1);
+#ifdef DEBUG_VLC
+                DEBUGF("%4x: n=%d (subtable)\n",
+                       j, n);
+#endif
+                /* compute table size */
+                n1 = -table[j][1]; //bits
+                if (n > n1)
+                    n1 = n;
+                table[j][1] = -n1; //bits
+            }
+        }
+    }
+
+    /* second pass : fill auxillary tables recursively */
+    for(i=0;i<table_size;i++) {
+        n = table[i][1]; //bits
+        if (n < 0) {
+            n = -n;
+            if (n > table_nb_bits) {
+                n = table_nb_bits;
+                table[i][1] = -n; //bits
+            }
+            index = build_table(vlc, n, nb_codes,
+                                bits, bits_wrap, bits_size,
+                                codes, codes_wrap, codes_size,
+                                symbols, symbols_wrap, symbols_size,
+                                (flags & INIT_VLC_LE) ? (code_prefix | (i << n_prefix)) : ((code_prefix << table_nb_bits) | i),
+                                n_prefix + table_nb_bits, flags);
+            if (index < 0)
+                return -1;
+            /* note: realloc has been done, so reload tables */
+            table = &vlc->table[table_index];
+            table[i][0] = index; //code
+        }
+    }
+    return table_index;
+}
+
+
+/* Build VLC decoding tables suitable for use with get_vlc().
+
+   'nb_bits' set thee decoding table size (2^nb_bits) entries. The
+   bigger it is, the faster is the decoding. But it should not be too
+   big to save memory and L1 cache. '9' is a good compromise.
+
+   'nb_codes' : number of vlcs codes
+
+   'bits' : table which gives the size (in bits) of each vlc code.
+
+   'codes' : table which gives the bit pattern of of each vlc code.
+
+   'symbols' : table which gives the values to be returned from get_vlc().
+
+   'xxx_wrap' : give the number of bytes between each entry of the
+   'bits' or 'codes' tables.
+
+   'xxx_size' : gives the number of bytes of each entry of the 'bits'
+   or 'codes' tables.
+
+   'wrap' and 'size' allows to use any memory configuration and types
+   (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
+
+   'use_static' should be set to 1 for tables, which should be freed
+   with av_free_static(), 0 if free_vlc() will be used.
+*/
+int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
+             const void *bits, int bits_wrap, int bits_size,
+             const void *codes, int codes_wrap, int codes_size,
+             const void *symbols, int symbols_wrap, int symbols_size,
+             int flags)
+{
+    vlc->bits = nb_bits;
+    if(flags & INIT_VLC_USE_NEW_STATIC){
+        if(vlc->table_size && vlc->table_size == vlc->table_allocated){
+            return 0;
+        }else if(vlc->table_size){
+            return -1; // fatal error, we are called on a partially initialized table
+        }
+    }else if(!(flags & INIT_VLC_USE_STATIC)) {
+        vlc->table = NULL;
+        vlc->table_allocated = 0;
+        vlc->table_size = 0;
+    } else {
+        /* Static tables are initially always NULL, return
+           if vlc->table != NULL to avoid double allocation */
+        if(vlc->table)
+            return 0;
+    }
+
+#ifdef DEBUG_VLC
+    DEBUGF("build table nb_codes=%d\n", nb_codes);
+#endif
+
+    if (build_table(vlc, nb_bits, nb_codes,
+                    bits, bits_wrap, bits_size,
+                    codes, codes_wrap, codes_size,
+                    symbols, symbols_wrap, symbols_size,
+                    0, 0, flags) < 0) {
+        //free(&vlc->table);
+        return -1;
+    }
+    /* Changed the following condition to be true if table_size > table_allocated. *
+     * This would be more sensible for static tables since we want warnings for    *
+     * memory shortages only.                                                      */
+#ifdef TEST
+    if((flags & INIT_VLC_USE_NEW_STATIC) && vlc->table_size > vlc->table_allocated)
+        DEBUGF("needed %d had %d\n", vlc->table_size, vlc->table_allocated);
+#endif
+    return 0;
+}
+
diff --git a/apps/codecs/lib/ffmpeg_bitstream.h b/apps/codecs/lib/ffmpeg_bitstream.h
new file mode 100644
index 0000000..f0105a4
--- /dev/null
+++ b/apps/codecs/lib/ffmpeg_bitstream.h
@@ -0,0 +1,963 @@
+/*
+ * copyright (c) 2004 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * 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 BITSTREAM_H
+#define BITSTREAM_H
+
+#include <inttypes.h>
+#include <stdlib.h>
+//#include <assert.h>
+#include <string.h>
+#include <stdio.h>
+#include "ffmpeg_bswap.h"
+
+/* The following 2 defines are taken from libavutil/intreadwrite.h */
+#define AV_RB32(x)  ((((const uint8_t*)(x))[0] << 24) | \
+                     (((const uint8_t*)(x))[1] << 16) | \
+                     (((const uint8_t*)(x))[2] <<  8) | \
+                      ((const uint8_t*)(x))[3])
+#define AV_WB32(p, d) do { \
+                    ((uint8_t*)(p))[3] = (d); \
+                    ((uint8_t*)(p))[2] = (d)>>8; \
+                    ((uint8_t*)(p))[1] = (d)>>16; \
+                    ((uint8_t*)(p))[0] = (d)>>24; } while(0)
+
+#if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER)
+#   define ALT_BITSTREAM_READER
+#endif
+
+//#define ALT_BITSTREAM_WRITER
+//#define ALIGNED_BITSTREAM_WRITER
+#if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
+#   if defined(ARCH_ARM)
+#       define A32_BITSTREAM_READER
+#   else
+#       define ALT_BITSTREAM_READER
+//#define LIBMPEG2_BITSTREAM_READER
+//#define A32_BITSTREAM_READER
+#   endif
+#endif
+
+extern const uint8_t ff_reverse[256];
+
+#if defined(ARCH_X86)
+// avoid +32 for shift optimization (gcc should do that ...)
+static inline  int32_t NEG_SSR32( int32_t a, int8_t s){
+    __asm__ ("sarl %1, %0\n\t"
+         : "+r" (a)
+         : "ic" ((uint8_t)(-s))
+    );
+    return a;
+}
+static inline uint32_t NEG_USR32(uint32_t a, int8_t s){
+    __asm__ ("shrl %1, %0\n\t"
+         : "+r" (a)
+         : "ic" ((uint8_t)(-s))
+    );
+    return a;
+}
+#else
+#    define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))
+#    define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
+#endif
+
+/* bit output */
+
+/* buf and buf_end must be present and used by every alternative writer. */
+typedef struct PutBitContext {
+#ifdef ALT_BITSTREAM_WRITER
+    uint8_t *buf, *buf_end;
+    int index;
+#else
+    uint32_t bit_buf;
+    int bit_left;
+    uint8_t *buf, *buf_ptr, *buf_end;
+#endif
+    int size_in_bits;
+} PutBitContext;
+
+static inline void init_put_bits(PutBitContext *s, uint8_t *buffer, int buffer_size)
+{
+    if(buffer_size < 0) {
+        buffer_size = 0;
+        buffer = NULL;
+    }
+
+    s->size_in_bits= 8*buffer_size;
+    s->buf = buffer;
+    s->buf_end = s->buf + buffer_size;
+#ifdef ALT_BITSTREAM_WRITER
+    s->index=0;
+    ((uint32_t*)(s->buf))[0]=0;
+//    memset(buffer, 0, buffer_size);
+#else
+    s->buf_ptr = s->buf;
+    s->bit_left=32;
+    s->bit_buf=0;
+#endif
+}
+
+/* return the number of bits output */
+static inline int put_bits_count(PutBitContext *s)
+{
+#ifdef ALT_BITSTREAM_WRITER
+    return s->index;
+#else
+    return (s->buf_ptr - s->buf) * 8 + 32 - s->bit_left;
+#endif
+}
+
+/* pad the end of the output stream with zeros */
+static inline void flush_put_bits(PutBitContext *s)
+{
+#ifdef ALT_BITSTREAM_WRITER
+    align_put_bits(s);
+#else
+#ifndef BITSTREAM_WRITER_LE
+    s->bit_buf<<= s->bit_left;
+#endif
+    while (s->bit_left < 32) {
+        /* XXX: should test end of buffer */
+#ifdef BITSTREAM_WRITER_LE
+        *s->buf_ptr++=s->bit_buf;
+        s->bit_buf>>=8;
+#else
+        *s->buf_ptr++=s->bit_buf >> 24;
+        s->bit_buf<<=8;
+#endif
+        s->bit_left+=8;
+    }
+    s->bit_left=32;
+    s->bit_buf=0;
+#endif
+}
+
+void align_put_bits(PutBitContext *s);
+void ff_put_string(PutBitContext * pbc, const char *s, int put_zero);
+void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length);
+
+/* bit input */
+/* buffer, buffer_end and size_in_bits must be present and used by every reader */
+typedef struct GetBitContext {
+    const uint8_t *buffer, *buffer_end;
+#ifdef ALT_BITSTREAM_READER
+    int index;
+#elif defined LIBMPEG2_BITSTREAM_READER
+    uint8_t *buffer_ptr;
+    uint32_t cache;
+    int bit_count;
+#elif defined A32_BITSTREAM_READER
+    uint32_t *buffer_ptr;
+    uint32_t cache0;
+    uint32_t cache1;
+    int bit_count;
+#endif
+    int size_in_bits;
+} GetBitContext;
+
+#define VLC_TYPE int16_t
+
+typedef struct VLC {
+    int bits;
+    VLC_TYPE (*table)[2]; ///< code, bits
+    int table_size, table_allocated;
+} VLC;
+
+typedef struct RL_VLC_ELEM {
+    int16_t level;
+    int8_t len;
+    uint8_t run;
+} RL_VLC_ELEM;
+
+#ifndef ALT_BITSTREAM_WRITER
+static inline void put_bits(PutBitContext *s, int n, unsigned int value)
+{
+    unsigned int bit_buf;
+    int bit_left;
+
+    //    printf("put_bits=%d %x\n", n, value);
+    //assert(n == 32 || value < (1U << n));
+
+    bit_buf = s->bit_buf;
+    bit_left = s->bit_left;
+
+    //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
+    /* XXX: optimize */
+#ifdef BITSTREAM_WRITER_LE
+    bit_buf |= value << (32 - bit_left);
+    if (n >= bit_left) {
+#if !HAVE_FAST_UNALIGNED
+        if (3 & (intptr_t) s->buf_ptr) {
+            AV_WL32(s->buf_ptr, bit_buf);
+        } else
+#endif
+        *(uint32_t *)s->buf_ptr = le2me_32(bit_buf);
+        s->buf_ptr+=4;
+        bit_buf = (bit_left==32)?0:value >> bit_left;
+        bit_left+=32;
+    }
+    bit_left-=n;
+#else
+    if (n < bit_left) {
+        bit_buf = (bit_buf<<n) | value;
+        bit_left-=n;
+    } else {
+        bit_buf<<=bit_left;
+        bit_buf |= value >> (n - bit_left);
+#if !defined(HAVE_FAST_UNALIGNED)
+        if (3 & (intptr_t) s->buf_ptr) {
+            AV_WB32(s->buf_ptr, bit_buf);
+        } else
+#endif
+        *(uint32_t *)s->buf_ptr = be2me_32(bit_buf);
+        //printf("bitbuf = %08x\n", bit_buf);
+        s->buf_ptr+=4;
+        bit_left+=32 - n;
+        bit_buf = value;
+    }
+#endif
+
+    s->bit_buf = bit_buf;
+    s->bit_left = bit_left;
+}
+#endif
+
+
+#ifdef ALT_BITSTREAM_WRITER
+static inline void put_bits(PutBitContext *s, int n, unsigned int value)
+{
+#    ifdef ALIGNED_BITSTREAM_WRITER
+#        if ARCH_X86
+    __asm__ volatile(
+        "movl %0, %%ecx                 \n\t"
+        "xorl %%eax, %%eax              \n\t"
+        "shrdl %%cl, %1, %%eax          \n\t"
+        "shrl %%cl, %1                  \n\t"
+        "movl %0, %%ecx                 \n\t"
+        "shrl $3, %%ecx                 \n\t"
+        "andl $0xFFFFFFFC, %%ecx        \n\t"
+        "bswapl %1                      \n\t"
+        "orl %1, (%2, %%ecx)            \n\t"
+        "bswapl %%eax                   \n\t"
+        "addl %3, %0                    \n\t"
+        "movl %%eax, 4(%2, %%ecx)       \n\t"
+        : "=&r" (s->index), "=&r" (value)
+        : "r" (s->buf), "r" (n), "0" (s->index), "1" (value<<(-n))
+        : "%eax", "%ecx"
+    );
+#        else
+    int index= s->index;
+    uint32_t *ptr= ((uint32_t *)s->buf)+(index>>5);
+
+    value<<= 32-n;
+
+    ptr[0] |= be2me_32(value>>(index&31));
+    ptr[1]  = be2me_32(value<<(32-(index&31)));
+//if(n>24) printf("%d %d\n", n, value);
+    index+= n;
+    s->index= index;
+#        endif
+#    else //ALIGNED_BITSTREAM_WRITER
+#        if ARCH_X86
+    __asm__ volatile(
+        "movl $7, %%ecx                 \n\t"
+        "andl %0, %%ecx                 \n\t"
+        "addl %3, %%ecx                 \n\t"
+        "negl %%ecx                     \n\t"
+        "shll %%cl, %1                  \n\t"
+        "bswapl %1                      \n\t"
+        "movl %0, %%ecx                 \n\t"
+        "shrl $3, %%ecx                 \n\t"
+        "orl %1, (%%ecx, %2)            \n\t"
+        "addl %3, %0                    \n\t"
+        "movl $0, 4(%%ecx, %2)          \n\t"
+        : "=&r" (s->index), "=&r" (value)
+        : "r" (s->buf), "r" (n), "0" (s->index), "1" (value)
+        : "%ecx"
+    );
+#        else
+    int index= s->index;
+    uint32_t *ptr= (uint32_t*)(((uint8_t *)s->buf)+(index>>3));
+
+    ptr[0] |= be2me_32(value<<(32-n-(index&7) ));
+    ptr[1] = 0;
+//if(n>24) printf("%d %d\n", n, value);
+    index+= n;
+    s->index= index;
+#        endif
+#    endif //!ALIGNED_BITSTREAM_WRITER
+}
+#endif
+
+static inline void put_sbits(PutBitContext *pb, int bits, int32_t val)
+{
+    //assert(bits >= 0 && bits <= 31);
+
+    put_bits(pb, bits, val & ((1<<bits)-1));
+}
+
+
+static inline uint8_t* pbBufPtr(PutBitContext *s)
+{
+#ifdef ALT_BITSTREAM_WRITER
+        return s->buf + (s->index>>3);
+#else
+        return s->buf_ptr;
+#endif
+}
+
+/**
+ *
+ * PutBitContext must be flushed & aligned to a byte boundary before calling this.
+ */
+static inline void skip_put_bytes(PutBitContext *s, int n){
+        //assert((put_bits_count(s)&7)==0);
+#ifdef ALT_BITSTREAM_WRITER
+        FIXME may need some cleaning of the buffer
+        s->index += n<<3;
+#else
+        //assert(s->bit_left==32);
+        s->buf_ptr += n;
+#endif
+}
+
+/**
+ * Skips the given number of bits.
+ * Must only be used if the actual values in the bitstream do not matter.
+ */
+static inline void skip_put_bits(PutBitContext *s, int n){
+#ifdef ALT_BITSTREAM_WRITER
+    s->index += n;
+#else
+    s->bit_left -= n;
+    s->buf_ptr-= s->bit_left>>5;
+    s->bit_left &= 31;
+#endif
+}
+
+/**
+ * Changes the end of the buffer.
+ */
+static inline void set_put_bits_buffer_size(PutBitContext *s, int size){
+    s->buf_end= s->buf + size;
+}
+
+/* Bitstream reader API docs:
+name
+    arbitrary name which is used as prefix for the internal variables
+
+gb
+    getbitcontext
+
+OPEN_READER(name, gb)
+    loads gb into local variables
+
+CLOSE_READER(name, gb)
+    stores local vars in gb
+
+UPDATE_CACHE(name, gb)
+    refills the internal cache from the bitstream
+    after this call at least MIN_CACHE_BITS will be available,
+
+GET_CACHE(name, gb)
+    will output the contents of the internal cache, next bit is MSB of 32 or 64 bit (FIXME 64bit)
+
+SHOW_UBITS(name, gb, num)
+    will return the next num bits
+
+SHOW_SBITS(name, gb, num)
+    will return the next num bits and do sign extension
+
+SKIP_BITS(name, gb, num)
+    will skip over the next num bits
+    note, this is equivalent to SKIP_CACHE; SKIP_COUNTER
+
+SKIP_CACHE(name, gb, num)
+    will remove the next num bits from the cache (note SKIP_COUNTER MUST be called before UPDATE_CACHE / CLOSE_READER)
+
+SKIP_COUNTER(name, gb, num)
+    will increment the internal bit counter (see SKIP_CACHE & SKIP_BITS)
+
+LAST_SKIP_CACHE(name, gb, num)
+    will remove the next num bits from the cache if it is needed for UPDATE_CACHE otherwise it will do nothing
+
+LAST_SKIP_BITS(name, gb, num)
+    is equivalent to SKIP_LAST_CACHE; SKIP_COUNTER
+
+for examples see get_bits, show_bits, skip_bits, get_vlc
+*/
+
+#ifdef ALT_BITSTREAM_READER
+#   define MIN_CACHE_BITS 25
+
+#   define OPEN_READER(name, gb)\
+        int name##_index= (gb)->index;\
+        int name##_cache= 0;\
+
+#   define CLOSE_READER(name, gb)\
+        (gb)->index= name##_index;\
+
+# ifdef ALT_BITSTREAM_READER_LE
+#   define UPDATE_CACHE(name, gb)\
+        name##_cache= AV_RL32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) >> (name##_index&0x07);\
+
+#   define SKIP_CACHE(name, gb, num)\
+        name##_cache >>= (num);
+# else
+#   define UPDATE_CACHE(name, gb)\
+        name##_cache= AV_RB32( ((const uint8_t *)(gb)->buffer)+(name##_index>>3) ) << (name##_index&0x07);\
+
+#   define SKIP_CACHE(name, gb, num)\
+        name##_cache <<= (num);
+# endif
+
+// FIXME name?
+#   define SKIP_COUNTER(name, gb, num)\
+        name##_index += (num);\
+
+#   define SKIP_BITS(name, gb, num)\
+        {\
+            SKIP_CACHE(name, gb, num)\
+            SKIP_COUNTER(name, gb, num)\
+        }\
+
+#   define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)
+#   define LAST_SKIP_CACHE(name, gb, num) ;
+
+# ifdef ALT_BITSTREAM_READER_LE
+#   define SHOW_UBITS(name, gb, num)\
+        ((name##_cache) & (NEG_USR32(0xffffffff,num)))
+
+#   define SHOW_SBITS(name, gb, num)\
+        NEG_SSR32((name##_cache)<<(32-(num)), num)
+# else
+#   define SHOW_UBITS(name, gb, num)\
+        NEG_USR32(name##_cache, num)
+
+#   define SHOW_SBITS(name, gb, num)\
+        NEG_SSR32(name##_cache, num)
+# endif
+
+#   define GET_CACHE(name, gb)\
+        ((uint32_t)name##_cache)
+
+static inline int get_bits_count(GetBitContext *s){
+    return s->index;
+}
+
+static inline void skip_bits_long(GetBitContext *s, int n){
+    s->index += n;
+}
+
+#elif defined LIBMPEG2_BITSTREAM_READER
+//libmpeg2 like reader
+
+#   define MIN_CACHE_BITS 17
+
+#   define OPEN_READER(name, gb)\
+        int name##_bit_count=(gb)->bit_count;\
+        int name##_cache= (gb)->cache;\
+        uint8_t * name##_buffer_ptr=(gb)->buffer_ptr;\
+
+#   define CLOSE_READER(name, gb)\
+        (gb)->bit_count= name##_bit_count;\
+        (gb)->cache= name##_cache;\
+        (gb)->buffer_ptr= name##_buffer_ptr;\
+
+#   define UPDATE_CACHE(name, gb)\
+    if(name##_bit_count >= 0){\
+        name##_cache+= AV_RB16(name##_buffer_ptr) << name##_bit_count; \
+        name##_buffer_ptr+=2;\
+        name##_bit_count-= 16;\
+    }\
+
+#   define SKIP_CACHE(name, gb, num)\
+        name##_cache <<= (num);\
+
+#   define SKIP_COUNTER(name, gb, num)\
+        name##_bit_count += (num);\
+
+#   define SKIP_BITS(name, gb, num)\
+        {\
+            SKIP_CACHE(name, gb, num)\
+            SKIP_COUNTER(name, gb, num)\
+        }\
+
+#   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
+#   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
+
+#   define SHOW_UBITS(name, gb, num)\
+        NEG_USR32(name##_cache, num)
+
+#   define SHOW_SBITS(name, gb, num)\
+        NEG_SSR32(name##_cache, num)
+
+#   define GET_CACHE(name, gb)\
+        ((uint32_t)name##_cache)
+
+static inline int get_bits_count(GetBitContext *s){
+    return (s->buffer_ptr - s->buffer)*8 - 16 + s->bit_count;
+}
+
+static inline void skip_bits_long(GetBitContext *s, int n){
+    OPEN_READER(re, s)
+    re_bit_count += n;
+    re_buffer_ptr += 2*(re_bit_count>>4);
+    re_bit_count &= 15;
+    re_cache = ((re_buffer_ptr[-2]<<8) + re_buffer_ptr[-1]) << (16+re_bit_count);
+    UPDATE_CACHE(re, s)
+    CLOSE_READER(re, s)
+}
+
+#elif defined A32_BITSTREAM_READER
+
+#   define MIN_CACHE_BITS 32
+
+#   define OPEN_READER(name, gb)\
+        int name##_bit_count=(gb)->bit_count;\
+        uint32_t name##_cache0= (gb)->cache0;\
+        uint32_t name##_cache1= (gb)->cache1;\
+        uint32_t * name##_buffer_ptr=(gb)->buffer_ptr;\
+
+#   define CLOSE_READER(name, gb)\
+        (gb)->bit_count= name##_bit_count;\
+        (gb)->cache0= name##_cache0;\
+        (gb)->cache1= name##_cache1;\
+        (gb)->buffer_ptr= name##_buffer_ptr;\
+
+#   define UPDATE_CACHE(name, gb)\
+    if(name##_bit_count > 0){\
+        const uint32_t next= be2me_32( *name##_buffer_ptr );\
+        name##_cache0 |= NEG_USR32(next,name##_bit_count);\
+        name##_cache1 |= next<<name##_bit_count;\
+        name##_buffer_ptr++;\
+        name##_bit_count-= 32;\
+    }\
+
+#if ARCH_X86
+#   define SKIP_CACHE(name, gb, num)\
+        __asm__(\
+            "shldl %2, %1, %0          \n\t"\
+            "shll %2, %1               \n\t"\
+            : "+r" (name##_cache0), "+r" (name##_cache1)\
+            : "Ic" ((uint8_t)(num))\
+           );
+#else
+#   define SKIP_CACHE(name, gb, num)\
+        name##_cache0 <<= (num);\
+        name##_cache0 |= NEG_USR32(name##_cache1,num);\
+        name##_cache1 <<= (num);
+#endif
+
+#   define SKIP_COUNTER(name, gb, num)\
+        name##_bit_count += (num);\
+
+#   define SKIP_BITS(name, gb, num)\
+        {\
+            SKIP_CACHE(name, gb, num)\
+            SKIP_COUNTER(name, gb, num)\
+        }\
+
+#   define LAST_SKIP_BITS(name, gb, num) SKIP_BITS(name, gb, num)
+#   define LAST_SKIP_CACHE(name, gb, num) SKIP_CACHE(name, gb, num)
+
+#   define SHOW_UBITS(name, gb, num)\
+        NEG_USR32(name##_cache0, num)
+
+#   define SHOW_SBITS(name, gb, num)\
+        NEG_SSR32(name##_cache0, num)
+
+#   define GET_CACHE(name, gb)\
+        (name##_cache0)
+
+static inline int get_bits_count(GetBitContext *s){
+    return ((uint8_t*)s->buffer_ptr - s->buffer)*8 - 32 + s->bit_count;
+}
+
+static inline void skip_bits_long(GetBitContext *s, int n){
+    OPEN_READER(re, s)
+    re_bit_count += n;
+    re_buffer_ptr += re_bit_count>>5;
+    re_bit_count &= 31;
+    re_cache0 = be2me_32( re_buffer_ptr[-1] ) << re_bit_count;
+    re_cache1 = 0;
+    UPDATE_CACHE(re, s)
+    CLOSE_READER(re, s)
+}
+
+#endif
+
+/**
+ * read mpeg1 dc style vlc (sign bit + mantisse with no MSB).
+ * if MSB not set it is negative
+ * @param n length in bits
+ * @author BERO
+ */
+static inline int get_xbits(GetBitContext *s, int n){
+    register int sign;
+    register int32_t cache;
+    OPEN_READER(re, s)
+    UPDATE_CACHE(re, s)
+    cache = GET_CACHE(re,s);
+    sign=(~cache)>>31;
+    LAST_SKIP_BITS(re, s, n)
+    CLOSE_READER(re, s)
+    return (NEG_USR32(sign ^ cache, n) ^ sign) - sign;
+}
+
+static inline int get_sbits(GetBitContext *s, int n){
+    register int tmp;
+    OPEN_READER(re, s)
+    UPDATE_CACHE(re, s)
+    tmp= SHOW_SBITS(re, s, n);
+    LAST_SKIP_BITS(re, s, n)
+    CLOSE_READER(re, s)
+    return tmp;
+}
+
+/**
+ * reads 1-17 bits.
+ * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
+ */
+static inline unsigned int get_bits(GetBitContext *s, int n){
+    register int tmp;
+    OPEN_READER(re, s)
+    UPDATE_CACHE(re, s)
+    tmp= SHOW_UBITS(re, s, n);
+    LAST_SKIP_BITS(re, s, n)
+    CLOSE_READER(re, s)
+    return tmp;
+}
+
+/**
+ * shows 1-17 bits.
+ * Note, the alt bitstream reader can read up to 25 bits, but the libmpeg2 reader can't
+ */
+static inline unsigned int show_bits(GetBitContext *s, int n){
+    register int tmp;
+    OPEN_READER(re, s)
+    UPDATE_CACHE(re, s)
+    tmp= SHOW_UBITS(re, s, n);
+//    CLOSE_READER(re, s)
+    return tmp;
+}
+
+static inline void skip_bits(GetBitContext *s, int n){
+ //Note gcc seems to optimize this to s->index+=n for the ALT_READER :))
+    OPEN_READER(re, s)
+    UPDATE_CACHE(re, s)
+    LAST_SKIP_BITS(re, s, n)
+    CLOSE_READER(re, s)
+}
+
+static inline unsigned int get_bits1(GetBitContext *s){
+#ifdef ALT_BITSTREAM_READER
+    int index= s->index;
+    uint8_t result= s->buffer[ index>>3 ];
+#ifdef ALT_BITSTREAM_READER_LE
+    result>>= (index&0x07);
+    result&= 1;
+#else
+    result<<= (index&0x07);
+    result>>= 8 - 1;
+#endif
+    index++;
+    s->index= index;
+
+    return result;
+#else
+    return get_bits(s, 1);
+#endif
+}
+
+static inline unsigned int show_bits1(GetBitContext *s){
+    return show_bits(s, 1);
+}
+
+static inline void skip_bits1(GetBitContext *s){
+    skip_bits(s, 1);
+}
+
+/**
+ * reads 0-32 bits.
+ */
+static inline unsigned int get_bits_long(GetBitContext *s, int n){
+    if(n<=17) return get_bits(s, n);
+    else{
+#ifdef ALT_BITSTREAM_READER_LE
+        int ret= get_bits(s, 16);
+        return ret | (get_bits(s, n-16) << 16);
+#else
+        int ret= get_bits(s, 16) << (n-16);
+        return ret | get_bits(s, n-16);
+#endif
+    }
+}
+
+#if 0
+/**
+ * reads 0-32 bits as a signed integer.
+ */
+static inline int get_sbits_long(GetBitContext *s, int n) {
+    return sign_extend(get_bits_long(s, n), n);
+}
+#endif
+
+/**
+ * shows 0-32 bits.
+ */
+static inline unsigned int show_bits_long(GetBitContext *s, int n){
+    if(n<=17) return show_bits(s, n);
+    else{
+        GetBitContext gb= *s;
+        return get_bits_long(&gb, n);
+    }
+}
+
+#if 0
+static inline int check_marker(GetBitContext *s, const char *msg)
+{
+    int bit= get_bits1(s);
+    if(!bit)
+        printf("Marker bit missing %s\n", msg);
+
+    return bit;
+}
+#endif
+
+/**
+ * init GetBitContext.
+ * @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes larger then the actual read bits
+ * because some optimized bitstream readers read 32 or 64 bit at once and could read over the end
+ * @param bit_size the size of the buffer in bits
+ */
+static inline void init_get_bits(GetBitContext *s,
+                   const uint8_t *buffer, int bit_size)
+{
+    int buffer_size= (bit_size+7)>>3;
+    if(buffer_size < 0 || bit_size < 0) {
+        buffer_size = bit_size = 0;
+        buffer = NULL;
+    }
+
+    s->buffer= buffer;
+    s->size_in_bits= bit_size;
+    s->buffer_end= buffer + buffer_size;
+#ifdef ALT_BITSTREAM_READER
+    s->index=0;
+#elif defined LIBMPEG2_BITSTREAM_READER
+    s->buffer_ptr = (uint8_t*)((intptr_t)buffer&(~1));
+    s->bit_count = 16 + 8*((intptr_t)buffer&1);
+    skip_bits_long(s, 0);
+#elif defined A32_BITSTREAM_READER
+    s->buffer_ptr = (uint32_t*)((intptr_t)buffer&(~3));
+    s->bit_count = 32 + 8*((intptr_t)buffer&3);
+    skip_bits_long(s, 0);
+#endif
+}
+
+static inline void align_get_bits(GetBitContext *s)
+{
+    int n= (-get_bits_count(s)) & 7;
+    if(n) skip_bits(s, n);
+}
+
+#define init_vlc(vlc, nb_bits, nb_codes,\
+                 bits, bits_wrap, bits_size,\
+                 codes, codes_wrap, codes_size,\
+                 flags)\
+        init_vlc_sparse(vlc, nb_bits, nb_codes,\
+                 bits, bits_wrap, bits_size,\
+                 codes, codes_wrap, codes_size,\
+                 NULL, 0, 0, flags)
+
+int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
+             const void *bits, int bits_wrap, int bits_size,
+             const void *codes, int codes_wrap, int codes_size,
+             const void *symbols, int symbols_wrap, int symbols_size,
+             int flags);
+#define INIT_VLC_USE_STATIC 1 ///< VERY strongly deprecated and forbidden
+#define INIT_VLC_LE         2
+#define INIT_VLC_USE_NEW_STATIC 4
+void free_vlc(VLC *vlc);
+
+#define INIT_VLC_STATIC(vlc, bits, a,b,c,d,e,f,g, static_size)\
+{\
+    static VLC_TYPE table[static_size][2];\
+    (vlc)->table= table;\
+    (vlc)->table_allocated= static_size;\
+    init_vlc(vlc, bits, a,b,c,d,e,f,g, INIT_VLC_USE_NEW_STATIC);\
+}
+
+
+/**
+ *
+ * if the vlc code is invalid and max_depth=1 than no bits will be removed
+ * if the vlc code is invalid and max_depth>1 than the number of bits removed
+ * is undefined
+ */
+#define GET_VLC(code, name, gb, table, bits, max_depth)\
+{\
+    int n, index, nb_bits;\
+\
+    index= SHOW_UBITS(name, gb, bits);\
+    code = table[index][0];\
+    n    = table[index][1];\
+\
+    if(max_depth > 1 && n < 0){\
+        LAST_SKIP_BITS(name, gb, bits)\
+        UPDATE_CACHE(name, gb)\
+\
+        nb_bits = -n;\
+\
+        index= SHOW_UBITS(name, gb, nb_bits) + code;\
+        code = table[index][0];\
+        n    = table[index][1];\
+        if(max_depth > 2 && n < 0){\
+            LAST_SKIP_BITS(name, gb, nb_bits)\
+            UPDATE_CACHE(name, gb)\
+\
+            nb_bits = -n;\
+\
+            index= SHOW_UBITS(name, gb, nb_bits) + code;\
+            code = table[index][0];\
+            n    = table[index][1];\
+        }\
+    }\
+    SKIP_BITS(name, gb, n)\
+}
+
+#define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update)\
+{\
+    int n, index, nb_bits;\
+\
+    index= SHOW_UBITS(name, gb, bits);\
+    level = table[index].level;\
+    n     = table[index].len;\
+\
+    if(max_depth > 1 && n < 0){\
+        SKIP_BITS(name, gb, bits)\
+        if(need_update){\
+            UPDATE_CACHE(name, gb)\
+        }\
+\
+        nb_bits = -n;\
+\
+        index= SHOW_UBITS(name, gb, nb_bits) + level;\
+        level = table[index].level;\
+        n     = table[index].len;\
+    }\
+    run= table[index].run;\
+    SKIP_BITS(name, gb, n)\
+}
+
+
+/**
+ * parses a vlc code, faster then get_vlc()
+ * @param bits is the number of bits which will be read at once, must be
+ *             identical to nb_bits in init_vlc()
+ * @param max_depth is the number of times bits bits must be read to completely
+ *                  read the longest vlc code
+ *                  = (max_vlc_length + bits - 1) / bits
+ */
+static inline int get_vlc2(GetBitContext *s, VLC_TYPE (*table)[2],
+                                  int bits, int max_depth)
+{
+    int code;
+
+    OPEN_READER(re, s)
+    UPDATE_CACHE(re, s)
+
+    GET_VLC(code, re, s, table, bits, max_depth)
+
+    CLOSE_READER(re, s)
+    return code;
+}
+
+//#define TRACE
+
+#ifdef TRACE
+static inline void print_bin(int bits, int n){
+    int i;
+
+    for(i=n-1; i>=0; i--){
+        printf("%d", (bits>>i)&1);
+    }
+    for(i=n; i<24; i++)
+        printf(" ");
+}
+
+static inline int get_bits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
+    int r= get_bits(s, n);
+
+    print_bin(r, n);
+    printf("%5d %2d %3d bit @%5d in %s %s:%d\n", r, n, r, get_bits_count(s)-n, file, func, line);
+    return r;
+}
+static inline int get_vlc_trace(GetBitContext *s, VLC_TYPE (*table)[2], int bits, int max_depth, char *file, const char *func, int line){
+    int show= show_bits(s, 24);
+    int pos= get_bits_count(s);
+    int r= get_vlc2(s, table, bits, max_depth);
+    int len= get_bits_count(s) - pos;
+    int bits2= show>>(24-len);
+
+    print_bin(bits2, len);
+
+    printf("%5d %2d %3d vlc @%5d in %s %s:%d\n", bits2, len, r, pos, file, func, line);
+    return r;
+}
+static inline int get_xbits_trace(GetBitContext *s, int n, char *file, const char *func, int line){
+    int show= show_bits(s, n);
+    int r= get_xbits(s, n);
+
+    print_bin(show, n);
+    printf("%5d %2d %3d xbt @%5d in %s %s:%d\n", show, n, r, get_bits_count(s)-n, file, func, line);
+    return r;
+}
+
+#define get_bits(s, n)  get_bits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
+#define get_bits1(s)    get_bits_trace(s, 1, __FILE__, __PRETTY_FUNCTION__, __LINE__)
+#define get_xbits(s, n) get_xbits_trace(s, n, __FILE__, __PRETTY_FUNCTION__, __LINE__)
+#define get_vlc(s, vlc)            get_vlc_trace(s, (vlc)->table, (vlc)->bits, 3, __FILE__, __PRETTY_FUNCTION__, __LINE__)
+#define get_vlc2(s, tab, bits, max) get_vlc_trace(s, tab, bits, max, __FILE__, __PRETTY_FUNCTION__, __LINE__)
+
+#define tprintf(p, ...) printf
+
+#else //TRACE
+#define tprintf(p, ...) {}
+#endif
+
+static inline int decode012(GetBitContext *gb){
+    int n;
+    n = get_bits1(gb);
+    if (n == 0)
+        return 0;
+    else
+        return get_bits1(gb) + 1;
+}
+
+static inline int decode210(GetBitContext *gb){
+    if (get_bits1(gb))
+        return 0;
+    else
+        return 2 - get_bits1(gb);
+}
+
+#endif /* BITSTREAM_H */