Initial revision

Originally committed as revision 5 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 469 insertions, 0 deletions

diff --git a/libavcodec/common.c b/libavcodec/common.c
new file mode 100644
index 0000000000..b9365c9d8d
--- /dev/null
+++ b/libavcodec/common.c
@@ -0,0 +1,469 @@
+/*
+ * Common bit i/o utils
+ * Copyright (c) 2000, 2001 Gerard Lantau.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#ifdef __FreeBSD__
+#include <sys/param.h>
+#endif
+#include <netinet/in.h>
+#include <math.h>
+#include "common.h"
+
+#define NDEBUG
+#include <assert.h>
+
+void init_put_bits(PutBitContext *s, 
+                   UINT8 *buffer, int buffer_size,
+                   void *opaque,
+                   void (*write_data)(void *, UINT8 *, int))
+{
+    s->buf = buffer;
+    s->buf_ptr = s->buf;
+    s->buf_end = s->buf + buffer_size;
+    s->bit_cnt=0;
+    s->bit_buf=0;
+    s->data_out_size = 0;
+    s->write_data = write_data;
+    s->opaque = opaque;
+}
+
+static void flush_buffer(PutBitContext *s)
+{
+    int size;
+    if (s->write_data) {
+        size = s->buf_ptr - s->buf;
+        if (size > 0)
+            s->write_data(s->opaque, s->buf, size);
+        s->buf_ptr = s->buf;
+        s->data_out_size += size;
+    }
+}
+
+void put_bits(PutBitContext *s, int n, unsigned int value)
+{
+    unsigned int bit_buf;
+    int bit_cnt;
+
+#ifdef STATS
+    st_out_bit_counts[st_current_index] += n;
+#endif
+    //    printf("put_bits=%d %x\n", n, value);
+    assert(n == 32 || value < (1U << n));
+
+    bit_buf = s->bit_buf;
+    bit_cnt = s->bit_cnt;
+
+    //    printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
+    /* XXX: optimize */
+    if (n < (32-bit_cnt)) {
+        bit_buf |= value << (32 - n - bit_cnt);
+        bit_cnt+=n;
+    } else {
+        bit_buf |= value >> (n + bit_cnt - 32);
+        *(UINT32 *)s->buf_ptr = htonl(bit_buf);
+        //printf("bitbuf = %08x\n", bit_buf);
+        s->buf_ptr+=4;
+        if (s->buf_ptr >= s->buf_end)
+            flush_buffer(s);
+        bit_cnt=bit_cnt + n - 32;
+        if (bit_cnt == 0) {
+            bit_buf = 0;
+        } else {
+            bit_buf = value << (32 - bit_cnt);
+        }
+    }
+    
+    s->bit_buf = bit_buf;
+    s->bit_cnt = bit_cnt;
+}
+
+/* return the number of bits output */
+long long get_bit_count(PutBitContext *s)
+{
+    return (s->buf_ptr - s->buf + s->data_out_size) * 8 + (long long)s->bit_cnt;
+}
+
+void align_put_bits(PutBitContext *s)
+{
+    put_bits(s,(8 - s->bit_cnt) & 7,0);
+}
+
+/* pad the end of the output stream with zeros */
+void flush_put_bits(PutBitContext *s)
+{
+    while (s->bit_cnt > 0) {
+        /* XXX: should test end of buffer */
+        *s->buf_ptr++=s->bit_buf >> 24;
+        s->bit_buf<<=8;
+        s->bit_cnt-=8;
+    }
+    flush_buffer(s);
+    s->bit_cnt=0;
+    s->bit_buf=0;
+}
+
+/* for jpeg : espace 0xff with 0x00 after it */
+void jput_bits(PutBitContext *s, int n, unsigned int value)
+{
+    unsigned int bit_buf, b;
+    int bit_cnt, i;
+    
+    assert(n == 32 || value < (1U << n));
+
+    bit_buf = s->bit_buf;
+    bit_cnt = s->bit_cnt;
+
+    //printf("n=%d value=%x cnt=%d buf=%x\n", n, value, bit_cnt, bit_buf);
+    /* XXX: optimize */
+    if (n < (32-bit_cnt)) {
+        bit_buf |= value << (32 - n - bit_cnt);
+        bit_cnt+=n;
+    } else {
+        bit_buf |= value >> (n + bit_cnt - 32);
+        /* handle escape */
+        for(i=0;i<4;i++) {
+            b = (bit_buf >> 24);
+            *(s->buf_ptr++) = b;
+            if (b == 0xff)
+                *(s->buf_ptr++) = 0;
+            bit_buf <<= 8;
+        }
+        /* we flush the buffer sooner to handle worst case */
+        if (s->buf_ptr >= (s->buf_end - 8))
+            flush_buffer(s);
+
+        bit_cnt=bit_cnt + n - 32;
+        if (bit_cnt == 0) {
+            bit_buf = 0;
+        } else {
+            bit_buf = value << (32 - bit_cnt);
+        }
+    }
+    
+    s->bit_buf = bit_buf;
+    s->bit_cnt = bit_cnt;
+}
+
+/* pad the end of the output stream with zeros */
+void jflush_put_bits(PutBitContext *s)
+{
+    unsigned int b;
+
+    while (s->bit_cnt > 0) {
+        b = s->bit_buf >> 24;
+        *s->buf_ptr++ = b;
+        if (b == 0xff)
+            *s->buf_ptr++ = 0;
+        s->bit_buf<<=8;
+        s->bit_cnt-=8;
+    }
+    flush_buffer(s);
+    s->bit_cnt=0;
+    s->bit_buf=0;
+}
+
+/* bit input functions */
+
+void init_get_bits(GetBitContext *s, 
+                   UINT8 *buffer, int buffer_size)
+{
+    s->buf = buffer;
+    s->buf_ptr = buffer;
+    s->buf_end = buffer + buffer_size;
+    s->bit_cnt = 0;
+    s->bit_buf = 0;
+    while (s->buf_ptr < s->buf_end && 
+           s->bit_cnt < 32) {
+        s->bit_buf |= (*s->buf_ptr++ << (24 - s->bit_cnt));
+        s->bit_cnt += 8;
+    }
+}
+
+/* n must be >= 1 and <= 32 */
+unsigned int get_bits(GetBitContext *s, int n)
+{
+    unsigned int val;
+    int bit_cnt;
+    unsigned int bit_buf;
+    UINT8 *buf_ptr;
+
+#ifdef STATS
+    st_bit_counts[st_current_index] += n;
+#endif
+
+    bit_cnt = s->bit_cnt;
+    bit_buf = s->bit_buf;
+    
+    bit_cnt -= n;
+    if (bit_cnt >= 0) {
+        /* most common case here */
+        val = bit_buf >> (32 - n);
+        bit_buf <<= n; 
+    } else {
+        val = bit_buf >> (32 - n);
+        buf_ptr = s->buf_ptr;
+        buf_ptr += 4;
+        /* handle common case: we can read everything */
+        if (buf_ptr <= s->buf_end) {
+            bit_buf = (buf_ptr[-4] << 24) |
+                (buf_ptr[-3] << 16) |
+                (buf_ptr[-2] << 8) |
+                (buf_ptr[-1]);
+        } else {
+            buf_ptr -= 4;
+            bit_buf = 0;
+            if (buf_ptr < s->buf_end)
+                bit_buf |= *buf_ptr++ << 24;
+            if (buf_ptr < s->buf_end)
+                bit_buf |= *buf_ptr++ << 16;
+            if (buf_ptr < s->buf_end)
+                bit_buf |= *buf_ptr++ << 8;
+            if (buf_ptr < s->buf_end)
+                bit_buf |= *buf_ptr++;
+        }
+        s->buf_ptr = buf_ptr;
+        val |= bit_buf >> (32 + bit_cnt);
+        bit_buf <<= - bit_cnt;
+        bit_cnt += 32;
+    }
+    s->bit_buf = bit_buf;
+    s->bit_cnt = bit_cnt;
+    return val;
+}
+
+void align_get_bits(GetBitContext *s)
+{
+    int n;
+    n = s->bit_cnt & 7;
+    if (n > 0) {
+        get_bits(s, n);
+    }
+}
+
+/* VLC decoding */
+
+//#define DEBUG_VLC
+
+#define GET_DATA(v, table, i, wrap, size) \
+{\
+    UINT8 *ptr = (UINT8 *)table + i * wrap;\
+    switch(size) {\
+    case 1:\
+        v = *(UINT8 *)ptr;\
+        break;\
+    case 2:\
+        v = *(UINT16 *)ptr;\
+        break;\
+    default:\
+        v = *(UINT32 *)ptr;\
+        break;\
+    }\
+}
+
+
+static int alloc_table(VLC *vlc, int size)
+{
+    int index;
+    index = vlc->table_size;
+    vlc->table_size += size;
+    if (vlc->table_size > vlc->table_allocated) {
+        vlc->table_allocated += (1 << vlc->bits);
+        vlc->table_bits = realloc(vlc->table_bits, 
+                                  sizeof(INT8) * vlc->table_allocated);
+        vlc->table_codes = realloc(vlc->table_codes,
+                                   sizeof(INT16) * vlc->table_allocated);
+        if (!vlc->table_bits ||
+            !vlc->table_codes)
+            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 code_prefix, int n_prefix)
+{
+    int i, j, k, n, table_size, table_index, nb, n1, index;
+    UINT32 code;
+    INT8 *table_bits;
+    INT16 *table_codes;
+
+    table_size = 1 << table_nb_bits;
+    table_index = alloc_table(vlc, table_size);
+#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_bits = &vlc->table_bits[table_index];
+    table_codes = &vlc->table_codes[table_index];
+
+    for(i=0;i<table_size;i++) {
+        table_bits[i] = 0;
+        table_codes[i] = -1;
+    }
+
+    /* 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
+                    printf("%4x: code=%d n=%d\n",
+                           j, i, n);
+#endif
+                    if (table_bits[j] != 0) {
+                        fprintf(stderr, "incorrect codes\n");
+                        exit(1);
+                    }
+                    table_bits[j] = n;
+                    table_codes[j] = i;
+                    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_bits[j];
+                if (n > n1)
+                    n1 = n;
+                table_bits[j] = -n1;
+            }
+        }
+    }
+
+    /* second pass : fill auxillary tables recursively */
+    for(i=0;i<table_size;i++) {
+        n = table_bits[i];
+        if (n < 0) {
+            n = -n;
+            if (n > table_nb_bits) {
+                n = table_nb_bits;
+                table_bits[i] = -n;
+            }
+            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);
+            if (index < 0)
+                return -1;
+            /* note: realloc has been done, so reload tables */
+            table_bits = &vlc->table_bits[table_index];
+            table_codes = &vlc->table_codes[table_index];
+            table_codes[i] = index;
+        }
+    }
+    return table_index;
+}
+
+
+/* wrap and size allow to handle most types of storage.  */
+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)
+{
+    vlc->bits = nb_bits;
+    vlc->table_bits = NULL;
+    vlc->table_codes = NULL;
+    vlc->table_allocated = 0;
+    vlc->table_size = 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) < 0) {
+        if (vlc->table_bits)
+            free(vlc->table_bits);
+        if (vlc->table_codes)
+            free(vlc->table_codes);
+        return -1;
+    }
+    return 0;
+}
+
+
+void free_vlc(VLC *vlc)
+{
+    free(vlc->table_bits);
+    free(vlc->table_codes);
+}
+
+int get_vlc(GetBitContext *s, VLC *vlc)
+{
+    int bit_cnt, code, n, nb_bits, index;
+    UINT32 bit_buf;
+    INT16 *table_codes;
+    INT8 *table_bits;
+    UINT8 *buf_ptr;
+
+    SAVE_BITS(s);
+    nb_bits = vlc->bits;
+    table_codes = vlc->table_codes;
+    table_bits = vlc->table_bits;
+    for(;;) {
+        SHOW_BITS(s, index, nb_bits);
+        code = table_codes[index];
+        n = table_bits[index];
+        if (n > 0) {
+            /* most common case */
+            FLUSH_BITS(n);
+#ifdef STATS
+            st_bit_counts[st_current_index] += n;
+#endif
+            break;
+        } else if (n == 0) {
+            return -1;
+        } else {
+            FLUSH_BITS(nb_bits);
+#ifdef STATS
+            st_bit_counts[st_current_index] += nb_bits;
+#endif
+            nb_bits = -n;
+            table_codes = vlc->table_codes + code;
+            table_bits = vlc->table_bits + code;
+        }
+    }
+    RESTORE_BITS(s);
+    return code;
+}