/*
 * 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 libavcodec/get_bits.h
 * 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"*/
#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])
/*#include "libavutil/log.h"
#include "mathops.h"*/

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

#if !defined(LIBMPEG2_BITSTREAM_READER) && !defined(A32_BITSTREAM_READER) && !defined(ALT_BITSTREAM_READER)
#   if 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 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 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;

/* 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.
 */
#if 0
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
  }
}

/**
 * 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<=17) return show_bits(s, n);
  else{
    GetBitContext gb= *s;
    return get_bits_long(&gb, n);
  }
}
#endif
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
 */
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);
}


#ifdef VLC
#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 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;
}
#endif

//#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

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 /* AVCODEC_GET_BITS_H */
