/* Lzlib - Compression library for the lzip format
   Copyright (C) 2009-2025 Antonio Diaz Diaz.

   This library is free software. Redistribution and use in source and
   binary forms, with or without modification, are permitted provided
   that the following conditions are met:

   1. Redistributions of source code must retain the above copyright
   notice, this list of conditions, and the following disclaimer.

   2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions, and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

   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.
*/

#ifndef max
  #define max(x,y) ((x) >= (y) ? (x) : (y))
#endif
#ifndef min
  #define min(x,y) ((x) <= (y) ? (x) : (y))
#endif

typedef int State;

enum { states = 12 };

static inline bool St_is_char( const State st ) { return st < 7; }

static inline State St_set_char( const State st )
  {
  static const State next[states] = { 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 4, 5 };
  return next[st];
  }
static inline State St_set_char_rep() { return 8; }
static inline State St_set_match( const State st )
  { return ( st < 7 ) ? 7 : 10; }
static inline State St_set_rep( const State st )
  { return ( st < 7 ) ? 8 : 11; }
static inline State St_set_shortrep( const State st )
  { return ( st < 7 ) ? 9 : 11; }


enum {
  min_dictionary_bits = 12,
  min_dictionary_size = 1 << min_dictionary_bits,	/* >= modeled_distances */
  max_dictionary_bits = 29,
  max_dictionary_size = 1 << max_dictionary_bits,
  literal_context_bits = 3,
  literal_pos_state_bits = 0,				/* not used */
  pos_state_bits = 2,
  pos_states = 1 << pos_state_bits,
  pos_state_mask = pos_states - 1,

  len_states = 4,
  dis_slot_bits = 6,
  start_dis_model = 4,
  end_dis_model = 14,
  modeled_distances = 1 << (end_dis_model / 2),		/* 128 */
  dis_align_bits = 4,
  dis_align_size = 1 << dis_align_bits,

  len_low_bits = 3,
  len_mid_bits = 3,
  len_high_bits = 8,
  len_low_symbols = 1 << len_low_bits,
  len_mid_symbols = 1 << len_mid_bits,
  len_high_symbols = 1 << len_high_bits,
  max_len_symbols = len_low_symbols + len_mid_symbols + len_high_symbols,

  min_match_len = 2,					/* must be 2 */
  max_match_len = min_match_len + max_len_symbols - 1,	/* 273 */
  min_match_len_limit = 5 };

static inline int get_len_state( const int len )
  { return min( len - min_match_len, len_states - 1 ); }

static inline int get_lit_state( const uint8_t prev_byte )
  { return prev_byte >> ( 8 - literal_context_bits ); }


enum { bit_model_move_bits = 5,
       bit_model_total_bits = 11,
       bit_model_total = 1 << bit_model_total_bits };

typedef int Bit_model;

static inline void Bm_init( Bit_model * const probability )
  { *probability = bit_model_total / 2; }

static inline void Bm_array_init( Bit_model bm[], const int size )
  { int i; for( i = 0; i < size; ++i ) Bm_init( &bm[i] ); }

typedef struct Len_model
  {
  Bit_model choice1;
  Bit_model choice2;
  Bit_model bm_low[pos_states][len_low_symbols];
  Bit_model bm_mid[pos_states][len_mid_symbols];
  Bit_model bm_high[len_high_symbols];
  } Len_model;

static inline void Lm_init( Len_model * const lm )
  {
  Bm_init( &lm->choice1 );
  Bm_init( &lm->choice2 );
  Bm_array_init( lm->bm_low[0], pos_states * len_low_symbols );
  Bm_array_init( lm->bm_mid[0], pos_states * len_mid_symbols );
  Bm_array_init( lm->bm_high, len_high_symbols );
  }


/* Table of CRCs of all 8-bit messages. */
static const uint32_t crc32[256] =
  {
  0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F,
  0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
  0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2,
  0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
  0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
  0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
  0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C,
  0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
  0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423,
  0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
  0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106,
  0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
  0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
  0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
  0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
  0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
  0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7,
  0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
  0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA,
  0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
  0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81,
  0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
  0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84,
  0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
  0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
  0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
  0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E,
  0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
  0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55,
  0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
  0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28,
  0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
  0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F,
  0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
  0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
  0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
  0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69,
  0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
  0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
  0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
  0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693,
  0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
  0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D };


static inline void CRC32_update_byte( uint32_t * const crc, const uint8_t byte )
  { *crc = crc32[(*crc^byte)&0xFF] ^ ( *crc >> 8 ); }

/* about as fast as it is possible without messing with endianness */
static inline void CRC32_update_buf( uint32_t * const crc,
                                     const uint8_t * const buffer,
                                     const int size )
  {
  int i;
  uint32_t c = *crc;
  for( i = 0; i < size; ++i )
    c = crc32[(c^buffer[i])&0xFF] ^ ( c >> 8 );
  *crc = c;
  }


static inline bool isvalid_ds( const unsigned dictionary_size )
  { return dictionary_size >= min_dictionary_size &&
           dictionary_size <= max_dictionary_size; }


static inline int real_bits( unsigned value )
  {
  int bits = 0;
  while( value > 0 ) { value >>= 1; ++bits; }
  return bits;
  }


static const uint8_t lzip_magic[4] = { 0x4C, 0x5A, 0x49, 0x50 }; /* "LZIP" */

enum { Lh_size = 6 };
typedef uint8_t Lzip_header[Lh_size];	/* 0-3 magic bytes */
					/*   4 version */
					/*   5 coded dictionary size */

static inline void Lh_set_magic( Lzip_header data )
  { memcpy( data, lzip_magic, 4 ); data[4] = 1; }

static inline bool Lh_check_magic( const Lzip_header data )
  { return memcmp( data, lzip_magic, 4 ) == 0; }

/* detect (truncated) header */
static inline bool Lh_check_prefix( const Lzip_header data, const int sz )
  {
  int i; for( i = 0; i < sz && i < 4; ++i )
    if( data[i] != lzip_magic[i] ) return false;
  return sz > 0;
  }

/* detect corrupt header */
static inline bool Lh_check_corrupt( const Lzip_header data )
  {
  int matches = 0;
  int i; for( i = 0; i < 4; ++i )
    if( data[i] == lzip_magic[i] ) ++matches;
  return matches > 1 && matches < 4;
  }

static inline uint8_t Lh_version( const Lzip_header data )
  { return data[4]; }

static inline bool Lh_check_version( const Lzip_header data )
  { return data[4] == 1; }

static inline unsigned Lh_get_dictionary_size( const Lzip_header data )
  {
  unsigned sz = 1 << ( data[5] & 0x1F );
  if( sz > min_dictionary_size )
    sz -= ( sz / 16 ) * ( ( data[5] >> 5 ) & 7 );
  return sz;
  }

static inline bool Lh_set_dictionary_size( Lzip_header data, const unsigned sz )
  {
  if( !isvalid_ds( sz ) ) return false;
  data[5] = real_bits( sz - 1 );
  if( sz > min_dictionary_size )
    {
    const unsigned base_size = 1 << data[5];
    const unsigned fraction = base_size / 16;
    unsigned i;
    for( i = 7; i >= 1; --i )
      if( base_size - ( i * fraction ) >= sz )
        { data[5] |= i << 5; break; }
    }
  return true;
  }

static inline bool Lh_check( const Lzip_header data )
  {
  return Lh_check_magic( data ) && Lh_check_version( data ) &&
         isvalid_ds( Lh_get_dictionary_size( data ) );
  }


enum { Lt_size = 20 };
typedef uint8_t Lzip_trailer[Lt_size];
			/*  0-3  CRC32 of the uncompressed data */
			/*  4-11 size of the uncompressed data */
			/* 12-19 member size including header and trailer */

static inline unsigned Lt_get_data_crc( const Lzip_trailer data )
  {
  unsigned tmp = 0;
  int i; for( i = 3; i >= 0; --i ) { tmp <<= 8; tmp += data[i]; }
  return tmp;
  }

static inline void Lt_set_data_crc( Lzip_trailer data, unsigned crc )
  { int i; for( i = 0; i <= 3; ++i ) { data[i] = (uint8_t)crc; crc >>= 8; } }

static inline unsigned long long Lt_get_data_size( const Lzip_trailer data )
  {
  unsigned long long tmp = 0;
  int i; for( i = 11; i >= 4; --i ) { tmp <<= 8; tmp += data[i]; }
  return tmp;
  }

static inline void Lt_set_data_size( Lzip_trailer data, unsigned long long sz )
  { int i; for( i = 4; i <= 11; ++i ) { data[i] = (uint8_t)sz; sz >>= 8; } }

static inline unsigned long long Lt_get_member_size( const Lzip_trailer data )
  {
  unsigned long long tmp = 0;
  int i; for( i = 19; i >= 12; --i ) { tmp <<= 8; tmp += data[i]; }
  return tmp;
  }

static inline void Lt_set_member_size( Lzip_trailer data, unsigned long long sz )
  { int i; for( i = 12; i <= 19; ++i ) { data[i] = (uint8_t)sz; sz >>= 8; } }
