1 |
#include "ftzopen.h" |
2 |
#include FT_INTERNAL_MEMORY_H |
3 |
#include FT_INTERNAL_STREAM_H |
4 |
#include FT_INTERNAL_DEBUG_H |
5 |
|
6 |
/* refill input buffer, return 0 on success, or -1 if eof |
7 |
*/ |
8 |
static int |
9 |
ft_lzwstate_refill( FT_LzwState state ) |
10 |
{ |
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int result = -1; |
12 |
|
13 |
if ( !state->in_eof ) |
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{ |
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FT_ULong count = FT_Stream_TryRead( state->source, |
16 |
state->in_buff, |
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sizeof( state->in_buff ) ); |
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|
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state->in_cursor = state->in_buff; |
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state->in_limit = state->in_buff + count; |
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state->in_eof = FT_BOOL( count < sizeof( state->in_buff ) ); |
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|
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if ( count > 0 ) |
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result = 0; |
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} |
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return result; |
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} |
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|
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|
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/* return new code of 'num_bits', or -1 if eof |
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*/ |
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static FT_Int32 |
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ft_lzwstate_get_code( FT_LzwState state, |
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FT_UInt num_bits ) |
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{ |
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FT_Int32 result = -1; |
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FT_UInt32 pad = state->pad; |
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FT_UInt pad_bits = state->pad_bits; |
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|
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while ( num_bits > pad_bits ) |
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{ |
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if ( state->in_cursor >= state->in_limit && |
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ft_lzwstate_refill( state ) < 0 ) |
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goto Exit; |
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|
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pad |= (FT_UInt32)(*state->in_cursor++) << pad_bits; |
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pad_bits += 8; |
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} |
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|
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result = (FT_Int32)( pad & LZW_MASK(num_bits) ); |
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state->pad_bits = pad_bits - num_bits; |
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state->pad = pad >> num_bits; |
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|
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Exit: |
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return result; |
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} |
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|
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|
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/* grow the character stack |
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*/ |
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static int |
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ft_lzwstate_stack_grow( FT_LzwState state ) |
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{ |
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if ( state->stack_top >= state->stack_size ) |
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{ |
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FT_Memory memory = state->memory; |
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FT_Error error; |
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FT_UInt old_size = state->stack_size; |
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FT_UInt new_size = old_size; |
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|
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new_size = new_size + (new_size >> 1) + 4; |
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|
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if ( state->stack == state->stack_0 ) |
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{ |
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state->stack = NULL; |
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old_size = 0; |
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} |
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|
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if ( FT_RENEW_ARRAY( state->stack, old_size, new_size ) ) |
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return -1; |
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|
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state->stack_size = new_size; |
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} |
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return 0; |
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} |
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|
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|
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/* grow the prefix/suffix arrays |
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*/ |
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static int |
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ft_lzwstate_prefix_grow( FT_LzwState state ) |
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{ |
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FT_UInt old_size = state->prefix_size; |
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FT_UInt new_size = old_size; |
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FT_Memory memory = state->memory; |
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FT_Error error; |
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|
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if ( new_size == 0 ) /* first allocation -> 9 bits */ |
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new_size = 512; |
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else |
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new_size += (new_size >> 2); /* don't grow too fast */ |
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|
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/* note that the 'suffix' array is located in the same memory block |
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* pointed to by 'prefix' |
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* |
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* I know that sizeof(FT_Byte) == 1 by definition, but it's clearer |
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* to write it literally |
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*/ |
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if ( FT_REALLOC( state->prefix, |
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old_size*(sizeof(FT_UShort)+sizeof(FT_Byte)), |
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new_size*(sizeof(FT_UShort)+sizeof(FT_Byte)) ) ) |
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return -1; |
113 |
|
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/* now adjust 'suffix' and move the data accordingly */ |
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state->suffix = (FT_Byte*)(state->prefix + new_size); |
116 |
|
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FT_MEM_MOVE( state->suffix, |
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state->prefix + old_size, |
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old_size * sizeof(FT_Byte) ); |
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|
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state->prefix_size = new_size; |
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return 0; |
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} |
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|
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|
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FT_LOCAL_DEF( void ) |
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ft_lzwstate_reset( FT_LzwState state ) |
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{ |
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state->in_cursor = state->in_buff; |
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state->in_limit = state->in_buff; |
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state->in_eof = 0; |
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state->pad_bits = 0; |
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state->pad = 0; |
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|
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state->stack_top = 0; |
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state->num_bits = LZW_INIT_BITS; |
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state->phase = FT_LZW_PHASE_START; |
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} |
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|
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|
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FT_LOCAL_DEF( void ) |
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ft_lzwstate_init( FT_LzwState state, |
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FT_Stream source ) |
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{ |
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FT_ZERO( state ); |
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|
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state->source = source; |
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state->memory = source->memory; |
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|
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state->prefix = NULL; |
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state->suffix = NULL; |
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state->prefix_size = 0; |
153 |
|
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state->stack = state->stack_0; |
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state->stack_size = sizeof(state->stack_0); |
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|
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ft_lzwstate_reset( state ); |
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} |
159 |
|
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|
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FT_LOCAL_DEF( void ) |
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ft_lzwstate_done( FT_LzwState state ) |
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{ |
164 |
FT_Memory memory = state->memory; |
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|
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ft_lzwstate_reset( state ); |
167 |
|
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if ( state->stack != state->stack_0 ) |
169 |
FT_FREE( state->stack ); |
170 |
|
171 |
FT_FREE( state->prefix ); |
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state->suffix = NULL; |
173 |
|
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FT_ZERO( state ); |
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} |
176 |
|
177 |
|
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#define FTLZW_STACK_PUSH(c) \ |
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FT_BEGIN_STMNT \ |
180 |
if ( state->stack_top >= state->stack_size && \ |
181 |
ft_lzwstate_stack_grow( state ) < 0 ) \ |
182 |
goto Eof; \ |
183 |
\ |
184 |
state->stack[ state->stack_top++ ] = (FT_Byte)(c); \ |
185 |
FT_END_STMNT |
186 |
|
187 |
|
188 |
|
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FT_LOCAL_DEF( FT_ULong ) |
190 |
ft_lzwstate_io( FT_LzwState state, |
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FT_Byte* buffer, |
192 |
FT_ULong out_size ) |
193 |
{ |
194 |
FT_ULong result = 0; |
195 |
|
196 |
FT_UInt num_bits = state->num_bits; |
197 |
FT_UInt free_ent = state->free_ent; |
198 |
FT_UInt old_char = state->old_char; |
199 |
FT_UInt old_code = state->old_code; |
200 |
FT_UInt in_code = state->in_code; |
201 |
|
202 |
if ( out_size == 0 ) |
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goto Exit; |
204 |
|
205 |
switch ( state->phase ) |
206 |
{ |
207 |
case FT_LZW_PHASE_START: |
208 |
{ |
209 |
FT_Byte max_bits; |
210 |
FT_Int32 c; |
211 |
|
212 |
/* skip magic bytes, and read max_bits + block_flag */ |
213 |
if ( FT_Stream_Seek( state->source, 2 ) != 0 || |
214 |
FT_Stream_TryRead( state->source, &max_bits, 1 ) != 1 ) |
215 |
goto Eof; |
216 |
|
217 |
state->max_bits = max_bits & LZW_BIT_MASK; |
218 |
state->block_mode = max_bits & LZW_BLOCK_MASK; |
219 |
state->max_free = (FT_UInt)((1UL << state->max_bits) - 256); |
220 |
|
221 |
if ( state->max_bits > LZW_MAX_BITS ) |
222 |
goto Eof; |
223 |
|
224 |
num_bits = LZW_INIT_BITS; |
225 |
free_ent = (state->block_mode ? LZW_FIRST : LZW_CLEAR) - 256; |
226 |
in_code = 0; |
227 |
|
228 |
state->free_bits = num_bits < state->max_bits |
229 |
? (FT_UInt)((1UL << num_bits) - 256) |
230 |
: state->max_free+1; |
231 |
|
232 |
c = ft_lzwstate_get_code( state, num_bits ); |
233 |
if ( c < 0 ) |
234 |
goto Eof; |
235 |
|
236 |
old_code = old_char = (FT_UInt)c; |
237 |
|
238 |
if ( buffer ) |
239 |
buffer[result] = (FT_Byte)old_char; |
240 |
|
241 |
if ( ++result >= out_size ) |
242 |
goto Exit; |
243 |
|
244 |
state->phase = FT_LZW_PHASE_CODE; |
245 |
} |
246 |
/* fall-through */ |
247 |
|
248 |
case FT_LZW_PHASE_CODE: |
249 |
{ |
250 |
FT_Int32 c; |
251 |
FT_UInt code; |
252 |
|
253 |
NextCode: |
254 |
c = ft_lzwstate_get_code( state, num_bits ); |
255 |
if ( c < 0 ) goto Eof; |
256 |
|
257 |
code = (FT_UInt)c; |
258 |
|
259 |
if ( code == LZW_CLEAR && state->block_mode ) |
260 |
{ |
261 |
free_ent = (LZW_FIRST-1)-256; /* why not LZW_FIRST-256 ? */ |
262 |
num_bits = LZW_INIT_BITS; |
263 |
|
264 |
state->free_bits = num_bits < state->max_bits |
265 |
? (FT_UInt)((1UL << num_bits) - 256) |
266 |
: state->max_free+1; |
267 |
|
268 |
c = ft_lzwstate_get_code( state, num_bits ); |
269 |
if ( c < 0 ) goto Eof; |
270 |
|
271 |
code = (FT_UInt)c; |
272 |
} |
273 |
|
274 |
in_code = code; /* save code for later */ |
275 |
|
276 |
if ( code >= 256U ) |
277 |
{ |
278 |
/* special case for KwKwKwK */ |
279 |
if ( code-256U >= free_ent ) |
280 |
{ |
281 |
FTLZW_STACK_PUSH( old_char ); |
282 |
code = old_code; |
283 |
} |
284 |
|
285 |
while ( code >= 256U ) |
286 |
{ |
287 |
FTLZW_STACK_PUSH( state->suffix[code-256] ); |
288 |
code = state->prefix[code-256]; |
289 |
} |
290 |
} |
291 |
|
292 |
old_char = code; |
293 |
FTLZW_STACK_PUSH(old_char); |
294 |
|
295 |
state->phase = FT_LZW_PHASE_STACK; |
296 |
} |
297 |
/* fall-through */ |
298 |
|
299 |
case FT_LZW_PHASE_STACK: |
300 |
{ |
301 |
while ( state->stack_top > 0 ) |
302 |
{ |
303 |
--state->stack_top; |
304 |
|
305 |
if ( buffer ) |
306 |
buffer[result] = state->stack[state->stack_top]; |
307 |
|
308 |
if ( ++result == out_size ) |
309 |
goto Exit; |
310 |
} |
311 |
|
312 |
/* now create new entry */ |
313 |
if ( free_ent < state->max_free ) |
314 |
{ |
315 |
if ( free_ent >= state->prefix_size && |
316 |
ft_lzwstate_prefix_grow( state ) < 0 ) |
317 |
goto Eof; |
318 |
|
319 |
FT_ASSERT( free_ent < state->prefix_size ); |
320 |
|
321 |
state->prefix[free_ent] = (FT_UShort) old_code; |
322 |
state->suffix[free_ent] = (FT_Byte) old_char; |
323 |
|
324 |
if ( ++free_ent == state->free_bits ) |
325 |
{ |
326 |
num_bits++; |
327 |
|
328 |
state->free_bits = num_bits < state->max_bits |
329 |
? (FT_UInt)((1UL << num_bits)-256) |
330 |
: state->max_free+1; |
331 |
} |
332 |
} |
333 |
|
334 |
old_code = in_code; |
335 |
|
336 |
state->phase = FT_LZW_PHASE_CODE; |
337 |
goto NextCode; |
338 |
} |
339 |
|
340 |
default: /* state == EOF */ |
341 |
; |
342 |
} |
343 |
Exit: |
344 |
state->num_bits = num_bits; |
345 |
state->free_ent = free_ent; |
346 |
state->old_code = old_code; |
347 |
state->old_char = old_char; |
348 |
state->in_code = in_code; |
349 |
|
350 |
return result; |
351 |
|
352 |
Eof: |
353 |
state->phase = FT_LZW_PHASE_EOF; |
354 |
goto Exit; |
355 |
} |