common.c -> bitstream.c (and the single non bitstream func -> utils.c)

common.h -> common.h/bitstream.h

Originally committed as revision 3777 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 287 insertions, 0 deletions

diff --git a/libavcodec/bitstream.c b/libavcodec/bitstream.c
new file mode 100644
index 0000000000..2678772c49
--- /dev/null
+++ b/libavcodec/bitstream.c
@@ -0,0 +1,287 @@
+/*
+ * Common bit i/o utils
+ * Copyright (c) 2000, 2001 Fabrice Bellard.
+ * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at>
+ */
+
+/**
+ * @file bitstream.c
+ * bitstream api.
+ */
+ 
+#include "avcodec.h"
+#include "bitstream.h"
+
+void align_put_bits(PutBitContext *s)
+{
+#ifdef ALT_BITSTREAM_WRITER
+    put_bits(s,(  - s->index) & 7,0);
+#else
+    put_bits(s,s->bit_left & 7,0);
+#endif
+}
+
+void put_string(PutBitContext * pbc, char *s, int put_zero)
+{
+    while(*s){
+        put_bits(pbc, 8, *s);
+        s++;
+    }
+    if(put_zero)
+        put_bits(pbc, 8, 0);
+}
+
+/* bit input functions */
+
+/** 
+ * reads 0-32 bits.
+ */
+unsigned int get_bits_long(GetBitContext *s, int n){
+    if(n<=17) return get_bits(s, n);
+    else{
+        int ret= get_bits(s, 16) << (n-16);
+        return ret | get_bits(s, n-16);
+    }
+}
+
+/** 
+ * shows 0-32 bits.
+ */
+unsigned int show_bits_long(GetBitContext *s, int n){
+    if(n<=17) return show_bits(s, n);
+    else{
+        GetBitContext gb= *s;
+        int ret= get_bits_long(s, n);
+        *s= gb;
+        return ret;
+    }
+}
+
+void align_get_bits(GetBitContext *s)
+{
+    int n= (-get_bits_count(s)) & 7;
+    if(n) skip_bits(s, n);
+}
+
+int check_marker(GetBitContext *s, const char *msg)
+{
+    int bit= get_bits1(s);
+    if(!bit)
+	    av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg);
+
+    return bit;
+}
+
+/* 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) {
+        vlc->table_allocated += (1 << vlc->bits);
+        if(use_static)
+            vlc->table = av_realloc_static(vlc->table,
+                                           sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
+        else
+            vlc->table = av_realloc(vlc->table,
+                                    sizeof(VLC_TYPE) * 2 * vlc->table_allocated);
+        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,
+                       uint32_t code_prefix, int n_prefix, int use_static)
+{
+    int i, j, k, n, table_size, table_index, nb, n1, index;
+    uint32_t code;
+    VLC_TYPE (*table)[2];
+
+    table_size = 1 << table_nb_bits;
+    table_index = alloc_table(vlc, table_size, use_static);
+#ifdef DEBUG_VLC
+    printf("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 defined(DEBUG_VLC) && 0
+        printf("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 (n > 0 && (code >> n) == 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++) {
+#ifdef DEBUG_VLC
+                    av_log(NULL, AV_LOG_DEBUG, "%4x: code=%d n=%d\n",
+                           j, i, n);
+#endif
+                    if (table[j][1] /*bits*/ != 0) {
+                        av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");
+                        return -1;
+                    }
+                    table[j][1] = n; //bits
+                    table[j][0] = i; //code
+                    j++;
+                }
+            } else {
+                n -= table_nb_bits;
+                j = (code >> n) & ((1 << table_nb_bits) - 1);
+#ifdef DEBUG_VLC
+                printf("%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,
+                                (code_prefix << table_nb_bits) | i,
+                                n_prefix + table_nb_bits, use_static);
+            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.
+
+   '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' and 'codes' 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(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,
+             int use_static)
+{
+    vlc->bits = nb_bits;
+    if(!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
+    printf("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,
+                    0, 0, use_static) < 0) {
+        av_free(vlc->table);
+        return -1;
+    }
+    return 0;
+}
+
+
+void free_vlc(VLC *vlc)
+{
+    av_free(vlc->table);
+}
+