path: root/lzip.h

/*  Lunzip - Decompressor for the lzip format
    Copyright (C) 2010-2016 Antonio Diaz Diaz.

    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, see <http://www.gnu.org/licenses/>.
*/

#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_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_short_rep( 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] ); }

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];
  };

static inline void Lm_init( struct 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 );
  }


struct Pretty_print
  {
  const char * name;
  const char * stdin_name;
  unsigned longest_name;
  bool first_post;
  };

static inline void Pp_init( struct Pretty_print * const pp,
                            const char * const filenames[],
                            const int num_filenames, const int verbosity )
  {
  unsigned stdin_name_len;
  int i;
  pp->name = 0;
  pp->stdin_name = "(stdin)";
  pp->longest_name = 0;
  pp->first_post = false;
  stdin_name_len = strlen( pp->stdin_name );

  if( verbosity <= 0 ) return;
  for( i = 0; i < num_filenames; ++i )
    {
    const char * const s = filenames[i];
    const unsigned len = (strcmp( s, "-" ) == 0) ? stdin_name_len : strlen( s );
    if( len > pp->longest_name ) pp->longest_name = len;
    }
  if( pp->longest_name == 0 ) pp->longest_name = stdin_name_len;
  }

static inline void Pp_set_name( struct Pretty_print * const pp,
                                const char * const filename )
  {
  if( filename && filename[0] && strcmp( filename, "-" ) != 0 )
    pp->name = filename;
  else pp->name = pp->stdin_name;
  pp->first_post = true;
  }

static inline void Pp_reset( struct Pretty_print * const pp )
  { if( pp->name && pp->name[0] ) pp->first_post = true; }
void Pp_show_msg( struct Pretty_print * const pp, const char * const msg );


typedef uint32_t CRC32[256];	/* Table of CRCs of all 8-bit messages. */

extern CRC32 crc32;

static inline void CRC32_init( void )
  {
  unsigned n;
  for( n = 0; n < 256; ++n )
    {
    unsigned c = n;
    int k;
    for( k = 0; k < 8; ++k )
      { if( c & 1 ) c = 0xEDB88320U ^ ( c >> 1 ); else c >>= 1; }
    crc32[n] = c;
    }
  }

static inline void CRC32_update_buf( uint32_t * const crc,
                                     const uint8_t * const buffer,
                                     const int size )
  {
  int i;
  for( i = 0; i < size; ++i )
    *crc = crc32[(*crc^buffer[i])&0xFF] ^ ( *crc >> 8 );
  }


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

typedef uint8_t File_header[6];		/* 0-3 magic bytes */
					/*   4 version */
					/*   5 coded_dict_size */
enum { Fh_size = 6 };

static inline bool Fh_verify_magic( const File_header data )
  { return ( memcmp( data, magic_string, 4 ) == 0 ); }

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

static inline uint8_t Fh_version( const File_header data )
  { return data[4]; }

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

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


typedef uint8_t File_trailer[20];
			/*  0-3  CRC32 of the uncompressed data */
			/*  4-11 size of the uncompressed data */
			/* 12-19 member size including header and trailer */

enum { Ft_size = 20 };

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

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

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


/* defined in main.c */
extern int verbosity;
void cleanup_and_fail( const int retval );
void show_error( const char * const msg, const int errcode, const bool help );