/*
  * 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
  */
 

 /**

  * @file

  * bitstream reader API header.

  */
 

 #ifndef AVCODEC_GET_BITS_H
 #define AVCODEC_GET_BITS_H

 #include <stdint.h>
 #include <stdlib.h>
 #include <assert.h>

 #include "libavutil/bswap.h"
 #include "libavutil/common.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/log.h"

 #include "mathops.h"

 #if defined(ALT_BITSTREAM_READER_LE) && !defined(ALT_BITSTREAM_READER)

 #   define ALT_BITSTREAM_READER

 #endif
 

 #if !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)

 #   if ARCH_ARM && !HAVE_FAST_UNALIGNED

 #       define A32_BITSTREAM_READER
 #   else

 #       define ALT_BITSTREAM_READER

 //#define A32_BITSTREAM_READER

 #   endif

 #endif

 /* 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 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;
 
 /* 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 LAST_SKIP_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)                \
     unsigned int name##_index = (gb)->index;    \

     av_unused unsigned int name##_cache

 #   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) do {        \
         SKIP_CACHE(name, gb, num);              \
         SKIP_COUNTER(name, gb, num);            \
     } while (0)

 
 #   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) zero_extend(name##_cache, num)

 #   define SHOW_SBITS(name, gb, num) sign_extend(name##_cache, 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(const GetBitContext *s){

     return s->index;
 }

 
 static inline void skip_bits_long(GetBitContext *s, int n){

     s->index += n;

 }
 

 #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) do {          \
         (gb)->bit_count  = name##_bit_count;    \
         (gb)->cache0     = name##_cache0;       \
         (gb)->cache1     = name##_cache1;       \
         (gb)->buffer_ptr = name##_buffer_ptr;   \

     } while (0)

 #   define UPDATE_CACHE(name, gb) do {                                  \
         if(name##_bit_count > 0){                                       \
             const uint32_t next = av_be2ne32(*name##_buffer_ptr);       \
             name##_cache0 |= NEG_USR32(next, name##_bit_count);         \
             name##_cache1 |= next << name##_bit_count;                  \
             name##_buffer_ptr++;                                        \
             name##_bit_count -= 32;                                     \
         }                                                               \
     } while (0)

 #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) do {               \
         name##_cache0 <<= (num);                        \
         name##_cache0 |= NEG_USR32(name##_cache1,num);  \
         name##_cache1 <<= (num);                        \

     } while (0)

 #endif
 

 #   define SKIP_COUNTER(name, gb, num) name##_bit_count += (num)

 #   define SKIP_BITS(name, gb, num) do {        \
         SKIP_CACHE(name, gb, num);              \
         SKIP_COUNTER(name, gb, num);            \
     } while (0)

 #   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(const 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 = av_be2ne32(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;
 }
 
 /**

  * Read 1-25 bits.

  */
 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 1-25 bits.

  */
 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);

     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

     unsigned int index = s->index;
     uint8_t result = s->buffer[index>>3];

 #ifdef ALT_BITSTREAM_READER_LE

     result >>= index & 7;
     result &= 1;

 #else

     result <<= index & 7;
     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 <= MIN_CACHE_BITS) 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

     }
 }
 
 /**

  * 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);
 }
 
 /**

  * shows 0-32 bits.
  */
 static inline unsigned int show_bits_long(GetBitContext *s, int n){

     if (n <= MIN_CACHE_BITS) return show_bits(s, n);
     else {
         GetBitContext gb = *s;

         return get_bits_long(&gb, n);

     }
 }
 
 static inline 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;
 }
 
 /**

  * 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

  *
  * While GetBitContext stores the buffer size, for performance reasons you are
  * responsible for checking for the buffer end yourself (take advantage of the padding)!

  */
 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 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_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) do {     \
         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);    \
     } while (0)

 /**
  *

  * If the vlc code is invalid and max_depth=1, then no bits will be removed.
  * If the vlc code is invalid and max_depth>1, then the number of bits removed
  * is undefined.

  */

 #define GET_VLC(code, name, gb, table, bits, max_depth) do {    \
         int n, nb_bits;                                         \
         unsigned int index;                                     \
                                                                 \
         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);                                 \
     } while (0)
 
 #define GET_RL_VLC(level, run, name, gb, table, bits, max_depth, need_update) do { \
         int n, nb_bits;                                                 \
         unsigned int index;                                             \
                                                                         \
         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);                                         \
     } while (0)

 
 
 /**
  * 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 av_always_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;
 }
 

 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);
 }
 
 static inline int get_bits_left(GetBitContext *gb)
 {
     return gb->size_in_bits - get_bits_count(gb);
 }
 

 //#define TRACE
 
 #ifdef TRACE
 static inline void print_bin(int bits, int n){
     int i;

     for (i = n-1; i >= 0; i--) {

         av_log(NULL, AV_LOG_DEBUG, "%d", (bits>>i)&1);

     }

     for (i = n; i < 24; i++)

         av_log(NULL, AV_LOG_DEBUG, " ");

 }
 

 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);

     av_log(NULL, AV_LOG_DEBUG, "%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);

     av_log(NULL, AV_LOG_DEBUG, "%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);

     av_log(NULL, AV_LOG_DEBUG, "%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, ...) av_log(p, AV_LOG_DEBUG, __VA_ARGS__)

 
 #else //TRACE

 #define tprintf(p, ...) {}

 #endif
 

 #endif /* AVCODEC_GET_BITS_H */