ref: c1b6d08291087287bceb4dc2ec2c82a295adc575
dir: /src/lzw/ftzopen.c/
#include "ftzopen.h"
#include FT_INTERNAL_MEMORY_H
#include FT_INTERNAL_STREAM_H
#include FT_INTERNAL_DEBUG_H
/* refill input buffer, return 0 on success, or -1 if eof
*/
static int
ft_lzwstate_refill( FT_LzwState state )
{
int result = -1;
if ( !state->in_eof )
{
FT_ULong count = FT_Stream_TryRead( state->source,
state->in_buff,
sizeof( state->in_buff ) );
state->in_cursor = state->in_buff;
state->in_limit = state->in_buff + count;
state->in_eof = FT_BOOL( count < sizeof( state->in_buff ) );
if ( count > 0 )
result = 0;
}
return result;
}
/* return new code of 'num_bits', or -1 if eof
*/
static FT_Int32
ft_lzwstate_get_code( FT_LzwState state,
FT_UInt num_bits )
{
FT_Int32 result = -1;
FT_UInt32 pad = state->pad;
FT_UInt pad_bits = state->pad_bits;
while ( num_bits > pad_bits )
{
if ( state->in_cursor >= state->in_limit &&
ft_lzwstate_refill( state ) < 0 )
goto Exit;
pad |= (FT_UInt32)(*state->in_cursor++) << pad_bits;
pad_bits += 8;
}
result = (FT_Int32)( pad & LZW_MASK(num_bits) );
state->pad_bits = pad_bits - num_bits;
state->pad = pad >> num_bits;
Exit:
return result;
}
/* grow the character stack
*/
static int
ft_lzwstate_stack_grow( FT_LzwState state )
{
if ( state->stack_top >= state->stack_size )
{
FT_Memory memory = state->memory;
FT_Error error;
FT_UInt old_size = state->stack_size;
FT_UInt new_size = old_size;
new_size = new_size + (new_size >> 1) + 4;
if ( state->stack == state->stack_0 )
{
state->stack = NULL;
old_size = 0;
}
if ( FT_RENEW_ARRAY( state->stack, old_size, new_size ) )
return -1;
state->stack_size = new_size;
}
return 0;
}
/* grow the prefix/suffix arrays
*/
static int
ft_lzwstate_prefix_grow( FT_LzwState state )
{
FT_UInt old_size = state->prefix_size;
FT_UInt new_size = old_size;
FT_Memory memory = state->memory;
FT_Error error;
if ( new_size == 0 ) /* first allocation -> 9 bits */
new_size = 512;
else
new_size += (new_size >> 2); /* don't grow too fast */
/* note that the 'suffix' array is located in the same memory block
* pointed to by 'prefix'
*
* I know that sizeof(FT_Byte) == 1 by definition, but it's clearer
* to write it literally
*/
if ( FT_REALLOC( state->prefix,
old_size*(sizeof(FT_UShort)+sizeof(FT_Byte)),
new_size*(sizeof(FT_UShort)+sizeof(FT_Byte)) ) )
return -1;
/* now adjust 'suffix' and move the data accordingly */
state->suffix = (FT_Byte*)(state->prefix + new_size);
FT_MEM_MOVE( state->suffix,
state->prefix + old_size,
old_size * sizeof(FT_Byte) );
state->prefix_size = new_size;
return 0;
}
FT_LOCAL_DEF( void )
ft_lzwstate_reset( FT_LzwState state )
{
state->in_cursor = state->in_buff;
state->in_limit = state->in_buff;
state->in_eof = 0;
state->pad_bits = 0;
state->pad = 0;
state->stack_top = 0;
state->num_bits = LZW_INIT_BITS;
state->phase = FT_LZW_PHASE_START;
}
FT_LOCAL_DEF( void )
ft_lzwstate_init( FT_LzwState state,
FT_Stream source )
{
FT_ZERO( state );
state->source = source;
state->memory = source->memory;
state->prefix = NULL;
state->suffix = NULL;
state->prefix_size = 0;
state->stack = state->stack_0;
state->stack_size = sizeof(state->stack_0);
ft_lzwstate_reset( state );
}
FT_LOCAL_DEF( void )
ft_lzwstate_done( FT_LzwState state )
{
FT_Memory memory = state->memory;
ft_lzwstate_reset( state );
if ( state->stack != state->stack_0 )
FT_FREE( state->stack );
FT_FREE( state->prefix );
state->suffix = NULL;
FT_ZERO( state );
}
#define FTLZW_STACK_PUSH(c) \
FT_BEGIN_STMNT \
if ( state->stack_top >= state->stack_size && \
ft_lzwstate_stack_grow( state ) < 0 ) \
goto Eof; \
\
state->stack[ state->stack_top++ ] = (FT_Byte)(c); \
FT_END_STMNT
FT_LOCAL_DEF( FT_ULong )
ft_lzwstate_io( FT_LzwState state,
FT_Byte* buffer,
FT_ULong out_size )
{
FT_ULong result = 0;
FT_UInt num_bits = state->num_bits;
FT_UInt free_ent = state->free_ent;
FT_UInt old_char = state->old_char;
FT_UInt old_code = state->old_code;
FT_UInt in_code = state->in_code;
if ( out_size == 0 )
goto Exit;
switch ( state->phase )
{
case FT_LZW_PHASE_START:
{
FT_Byte max_bits;
FT_Int32 c;
/* skip magic bytes, and read max_bits + block_flag */
if ( FT_Stream_Seek( state->source, 2 ) != 0 ||
FT_Stream_TryRead( state->source, &max_bits, 1 ) != 1 )
goto Eof;
state->max_bits = max_bits & LZW_BIT_MASK;
state->block_mode = max_bits & LZW_BLOCK_MASK;
state->max_free = (FT_UInt)((1UL << state->max_bits) - 256);
if ( state->max_bits > LZW_MAX_BITS )
goto Eof;
num_bits = LZW_INIT_BITS;
free_ent = (state->block_mode ? LZW_FIRST : LZW_CLEAR) - 256;
in_code = 0;
state->free_bits = num_bits < state->max_bits
? (FT_UInt)((1UL << num_bits) - 256)
: state->max_free+1;
c = ft_lzwstate_get_code( state, num_bits );
if ( c < 0 )
goto Eof;
old_code = old_char = (FT_UInt)c;
if ( buffer )
buffer[result] = (FT_Byte)old_char;
if ( ++result >= out_size )
goto Exit;
state->phase = FT_LZW_PHASE_CODE;
}
/* fall-through */
case FT_LZW_PHASE_CODE:
{
FT_Int32 c;
FT_UInt code;
NextCode:
c = ft_lzwstate_get_code( state, num_bits );
if ( c < 0 ) goto Eof;
code = (FT_UInt)c;
if ( code == LZW_CLEAR && state->block_mode )
{
free_ent = (LZW_FIRST-1)-256; /* why not LZW_FIRST-256 ? */
num_bits = LZW_INIT_BITS;
state->free_bits = num_bits < state->max_bits
? (FT_UInt)((1UL << num_bits) - 256)
: state->max_free+1;
c = ft_lzwstate_get_code( state, num_bits );
if ( c < 0 ) goto Eof;
code = (FT_UInt)c;
}
in_code = code; /* save code for later */
if ( code >= 256U )
{
/* special case for KwKwKwK */
if ( code-256U >= free_ent )
{
FTLZW_STACK_PUSH( old_char );
code = old_code;
}
while ( code >= 256U )
{
FTLZW_STACK_PUSH( state->suffix[code-256] );
code = state->prefix[code-256];
}
}
old_char = code;
FTLZW_STACK_PUSH(old_char);
state->phase = FT_LZW_PHASE_STACK;
}
/* fall-through */
case FT_LZW_PHASE_STACK:
{
while ( state->stack_top > 0 )
{
--state->stack_top;
if ( buffer )
buffer[result] = state->stack[state->stack_top];
if ( ++result == out_size )
goto Exit;
}
/* now create new entry */
if ( free_ent < state->max_free )
{
if ( free_ent >= state->prefix_size &&
ft_lzwstate_prefix_grow( state ) < 0 )
goto Eof;
FT_ASSERT( free_ent < state->prefix_size );
state->prefix[free_ent] = (FT_UShort) old_code;
state->suffix[free_ent] = (FT_Byte) old_char;
if ( ++free_ent == state->free_bits )
{
num_bits++;
state->free_bits = num_bits < state->max_bits
? (FT_UInt)((1UL << num_bits)-256)
: state->max_free+1;
}
}
old_code = in_code;
state->phase = FT_LZW_PHASE_CODE;
goto NextCode;
}
default: /* state == EOF */
;
}
Exit:
state->num_bits = num_bits;
state->free_ent = free_ent;
state->old_code = old_code;
state->old_char = old_char;
state->in_code = in_code;
return result;
Eof:
state->phase = FT_LZW_PHASE_EOF;
goto Exit;
}