1 #if !defined(_FX_JPEG_TURBO_)
2 /*
3  * jcphuff.c
4  *
5  * Copyright (C) 1995-1997, Thomas G. Lane.
6  * This file is part of the Independent JPEG Group's software.
7  * For conditions of distribution and use, see the accompanying README file.
8  *
9  * This file contains Huffman entropy encoding routines for progressive JPEG.
10  *
11  * We do not support output suspension in this module, since the library
12  * currently does not allow multiple-scan files to be written with output
13  * suspension.
14  */
15 
16 #define JPEG_INTERNALS
17 #include "jinclude.h"
18 #include "jpeglib.h"
19 #include "jchuff.h"		/* Declarations shared with jchuff.c */
20 
21 #ifdef C_PROGRESSIVE_SUPPORTED
22 
23 /* Expanded entropy encoder object for progressive Huffman encoding. */
24 
25 typedef struct {
26   struct jpeg_entropy_encoder pub; /* public fields */
27 
28   /* Mode flag: TRUE for optimization, FALSE for actual data output */
29   boolean gather_statistics;
30 
31   /* Bit-level coding status.
32    * next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
33    */
34   JOCTET * next_output_byte;	/* => next byte to write in buffer */
35   size_t free_in_buffer;	/* # of byte spaces remaining in buffer */
36   INT32 put_buffer;		/* current bit-accumulation buffer */
37   int put_bits;			/* # of bits now in it */
38   j_compress_ptr cinfo;		/* link to cinfo (needed for dump_buffer) */
39 
40   /* Coding status for DC components */
41   int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
42 
43   /* Coding status for AC components */
44   int ac_tbl_no;		/* the table number of the single component */
45   unsigned int EOBRUN;		/* run length of EOBs */
46   unsigned int BE;		/* # of buffered correction bits before MCU */
47   char * bit_buffer;		/* buffer for correction bits (1 per char) */
48   /* packing correction bits tightly would save some space but cost time... */
49 
50   unsigned int restarts_to_go;	/* MCUs left in this restart interval */
51   int next_restart_num;		/* next restart number to write (0-7) */
52 
53   /* Pointers to derived tables (these workspaces have image lifespan).
54    * Since any one scan codes only DC or only AC, we only need one set
55    * of tables, not one for DC and one for AC.
56    */
57   c_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
58 
59   /* Statistics tables for optimization; again, one set is enough */
60   long * count_ptrs[NUM_HUFF_TBLS];
61 } phuff_entropy_encoder;
62 
63 typedef phuff_entropy_encoder * phuff_entropy_ptr;
64 
65 /* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
66  * buffer can hold.  Larger sizes may slightly improve compression, but
67  * 1000 is already well into the realm of overkill.
68  * The minimum safe size is 64 bits.
69  */
70 
71 #define MAX_CORR_BITS  1000	/* Max # of correction bits I can buffer */
72 
73 /* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32.
74  * We assume that int right shift is unsigned if INT32 right shift is,
75  * which should be safe.
76  */
77 
78 #ifdef RIGHT_SHIFT_IS_UNSIGNED
79 #define ISHIFT_TEMPS	int ishift_temp;
80 #define IRIGHT_SHIFT(x,shft)  \
81 	((ishift_temp = (x)) < 0 ? \
82 	 (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
83 	 (ishift_temp >> (shft)))
84 #else
85 #define ISHIFT_TEMPS
86 #define IRIGHT_SHIFT(x,shft)	((x) >> (shft))
87 #endif
88 
89 /* Forward declarations */
90 METHODDEF(boolean) encode_mcu_DC_first JPP((j_compress_ptr cinfo,
91 					    JBLOCKROW *MCU_data));
92 METHODDEF(boolean) encode_mcu_AC_first JPP((j_compress_ptr cinfo,
93 					    JBLOCKROW *MCU_data));
94 METHODDEF(boolean) encode_mcu_DC_refine JPP((j_compress_ptr cinfo,
95 					     JBLOCKROW *MCU_data));
96 METHODDEF(boolean) encode_mcu_AC_refine JPP((j_compress_ptr cinfo,
97 					     JBLOCKROW *MCU_data));
98 METHODDEF(void) finish_pass_phuff JPP((j_compress_ptr cinfo));
99 METHODDEF(void) finish_pass_gather_phuff JPP((j_compress_ptr cinfo));
100 
101 
102 /*
103  * Initialize for a Huffman-compressed scan using progressive JPEG.
104  */
105 
106 METHODDEF(void)
start_pass_phuff(j_compress_ptr cinfo,boolean gather_statistics)107 start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics)
108 {
109   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
110   boolean is_DC_band;
111   int ci, tbl;
112   jpeg_component_info * compptr;
113 
114   entropy->cinfo = cinfo;
115   entropy->gather_statistics = gather_statistics;
116 
117   is_DC_band = (cinfo->Ss == 0);
118 
119   /* We assume jcmaster.c already validated the scan parameters. */
120 
121   /* Select execution routines */
122   if (cinfo->Ah == 0) {
123     if (is_DC_band)
124       entropy->pub.encode_mcu = encode_mcu_DC_first;
125     else
126       entropy->pub.encode_mcu = encode_mcu_AC_first;
127   } else {
128     if (is_DC_band)
129       entropy->pub.encode_mcu = encode_mcu_DC_refine;
130     else {
131       entropy->pub.encode_mcu = encode_mcu_AC_refine;
132       /* AC refinement needs a correction bit buffer */
133       if (entropy->bit_buffer == NULL)
134 	entropy->bit_buffer = (char *)
135 	  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
136 				      MAX_CORR_BITS * SIZEOF(char));
137     }
138   }
139   if (gather_statistics)
140     entropy->pub.finish_pass = finish_pass_gather_phuff;
141   else
142     entropy->pub.finish_pass = finish_pass_phuff;
143 
144   /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
145    * for AC coefficients.
146    */
147   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
148     compptr = cinfo->cur_comp_info[ci];
149     /* Initialize DC predictions to 0 */
150     entropy->last_dc_val[ci] = 0;
151     /* Get table index */
152     if (is_DC_band) {
153       if (cinfo->Ah != 0)	/* DC refinement needs no table */
154 	continue;
155       tbl = compptr->dc_tbl_no;
156     } else {
157       entropy->ac_tbl_no = tbl = compptr->ac_tbl_no;
158     }
159     if (gather_statistics) {
160       /* Check for invalid table index */
161       /* (make_c_derived_tbl does this in the other path) */
162       if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
163         ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
164       /* Allocate and zero the statistics tables */
165       /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
166       if (entropy->count_ptrs[tbl] == NULL)
167 	entropy->count_ptrs[tbl] = (long *)
168 	  (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
169 				      257 * SIZEOF(long));
170       MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long));
171     } else {
172       /* Compute derived values for Huffman table */
173       /* We may do this more than once for a table, but it's not expensive */
174       jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl,
175 			      & entropy->derived_tbls[tbl]);
176     }
177   }
178 
179   /* Initialize AC stuff */
180   entropy->EOBRUN = 0;
181   entropy->BE = 0;
182 
183   /* Initialize bit buffer to empty */
184   entropy->put_buffer = 0;
185   entropy->put_bits = 0;
186 
187   /* Initialize restart stuff */
188   entropy->restarts_to_go = cinfo->restart_interval;
189   entropy->next_restart_num = 0;
190 }
191 
192 
193 /* Outputting bytes to the file.
194  * NB: these must be called only when actually outputting,
195  * that is, entropy->gather_statistics == FALSE.
196  */
197 
198 /* Emit a byte */
199 #define emit_byte(entropy,val)  \
200 	{ *(entropy)->next_output_byte++ = (JOCTET) (val);  \
201 	  if (--(entropy)->free_in_buffer == 0)  \
202 	    dump_buffer(entropy); }
203 
204 
205 LOCAL(void)
dump_buffer(phuff_entropy_ptr entropy)206 dump_buffer (phuff_entropy_ptr entropy)
207 /* Empty the output buffer; we do not support suspension in this module. */
208 {
209   struct jpeg_destination_mgr * dest = entropy->cinfo->dest;
210 
211   if (! (*dest->empty_output_buffer) (entropy->cinfo))
212     ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
213   /* After a successful buffer dump, must reset buffer pointers */
214   entropy->next_output_byte = dest->next_output_byte;
215   entropy->free_in_buffer = dest->free_in_buffer;
216 }
217 
218 
219 /* Outputting bits to the file */
220 
221 /* Only the right 24 bits of put_buffer are used; the valid bits are
222  * left-justified in this part.  At most 16 bits can be passed to emit_bits
223  * in one call, and we never retain more than 7 bits in put_buffer
224  * between calls, so 24 bits are sufficient.
225  */
226 
227 INLINE
LOCAL(void)228 LOCAL(void)
229 emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size)
230 /* Emit some bits, unless we are in gather mode */
231 {
232   /* This routine is heavily used, so it's worth coding tightly. */
233   register INT32 put_buffer = (INT32) code;
234   register int put_bits = entropy->put_bits;
235 
236   /* if size is 0, caller used an invalid Huffman table entry */
237   if (size == 0)
238     ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
239 
240   if (entropy->gather_statistics)
241     return;			/* do nothing if we're only getting stats */
242 
243   put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */
244 
245   put_bits += size;		/* new number of bits in buffer */
246 
247   put_buffer <<= 24 - put_bits; /* align incoming bits */
248 
249   put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */
250 
251   while (put_bits >= 8) {
252     int c = (int) ((put_buffer >> 16) & 0xFF);
253 
254     emit_byte(entropy, c);
255     if (c == 0xFF) {		/* need to stuff a zero byte? */
256       emit_byte(entropy, 0);
257     }
258     put_buffer <<= 8;
259     put_bits -= 8;
260   }
261 
262   entropy->put_buffer = put_buffer; /* update variables */
263   entropy->put_bits = put_bits;
264 }
265 
266 
267 LOCAL(void)
flush_bits(phuff_entropy_ptr entropy)268 flush_bits (phuff_entropy_ptr entropy)
269 {
270   emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */
271   entropy->put_buffer = 0;     /* and reset bit-buffer to empty */
272   entropy->put_bits = 0;
273 }
274 
275 
276 /*
277  * Emit (or just count) a Huffman symbol.
278  */
279 
280 INLINE
LOCAL(void)281 LOCAL(void)
282 emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol)
283 {
284   if (entropy->gather_statistics)
285     entropy->count_ptrs[tbl_no][symbol]++;
286   else {
287     c_derived_tbl * tbl = entropy->derived_tbls[tbl_no];
288     emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
289   }
290 }
291 
292 
293 /*
294  * Emit bits from a correction bit buffer.
295  */
296 
297 LOCAL(void)
emit_buffered_bits(phuff_entropy_ptr entropy,char * bufstart,unsigned int nbits)298 emit_buffered_bits (phuff_entropy_ptr entropy, char * bufstart,
299 		    unsigned int nbits)
300 {
301   if (entropy->gather_statistics)
302     return;			/* no real work */
303 
304   while (nbits > 0) {
305     emit_bits(entropy, (unsigned int) (*bufstart), 1);
306     bufstart++;
307     nbits--;
308   }
309 }
310 
311 
312 /*
313  * Emit any pending EOBRUN symbol.
314  */
315 
316 LOCAL(void)
emit_eobrun(phuff_entropy_ptr entropy)317 emit_eobrun (phuff_entropy_ptr entropy)
318 {
319   register int temp, nbits;
320 
321   if (entropy->EOBRUN > 0) {	/* if there is any pending EOBRUN */
322     temp = entropy->EOBRUN;
323     nbits = 0;
324     while ((temp >>= 1))
325       nbits++;
326     /* safety check: shouldn't happen given limited correction-bit buffer */
327     if (nbits > 14)
328       ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
329 
330     emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
331     if (nbits)
332       emit_bits(entropy, entropy->EOBRUN, nbits);
333 
334     entropy->EOBRUN = 0;
335 
336     /* Emit any buffered correction bits */
337     emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
338     entropy->BE = 0;
339   }
340 }
341 
342 
343 /*
344  * Emit a restart marker & resynchronize predictions.
345  */
346 
347 LOCAL(void)
emit_restart(phuff_entropy_ptr entropy,int restart_num)348 emit_restart (phuff_entropy_ptr entropy, int restart_num)
349 {
350   int ci;
351 
352   emit_eobrun(entropy);
353 
354   if (! entropy->gather_statistics) {
355     flush_bits(entropy);
356     emit_byte(entropy, 0xFF);
357     emit_byte(entropy, JPEG_RST0 + restart_num);
358   }
359 
360   if (entropy->cinfo->Ss == 0) {
361     /* Re-initialize DC predictions to 0 */
362     for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)
363       entropy->last_dc_val[ci] = 0;
364   } else {
365     /* Re-initialize all AC-related fields to 0 */
366     entropy->EOBRUN = 0;
367     entropy->BE = 0;
368   }
369 }
370 
371 
372 /*
373  * MCU encoding for DC initial scan (either spectral selection,
374  * or first pass of successive approximation).
375  */
376 
377 METHODDEF(boolean)
encode_mcu_DC_first(j_compress_ptr cinfo,JBLOCKROW * MCU_data)378 encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
379 {
380   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
381   register int temp, temp2;
382   register int nbits;
383   int blkn, ci;
384   int Al = cinfo->Al;
385   JBLOCKROW block;
386   jpeg_component_info * compptr;
387   ISHIFT_TEMPS
388 
389   entropy->next_output_byte = cinfo->dest->next_output_byte;
390   entropy->free_in_buffer = cinfo->dest->free_in_buffer;
391 
392   /* Emit restart marker if needed */
393   if (cinfo->restart_interval)
394     if (entropy->restarts_to_go == 0)
395       emit_restart(entropy, entropy->next_restart_num);
396 
397   /* Encode the MCU data blocks */
398   for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
399     block = MCU_data[blkn];
400     ci = cinfo->MCU_membership[blkn];
401     compptr = cinfo->cur_comp_info[ci];
402 
403     /* Compute the DC value after the required point transform by Al.
404      * This is simply an arithmetic right shift.
405      */
406     temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);
407 
408     /* DC differences are figured on the point-transformed values. */
409     temp = temp2 - entropy->last_dc_val[ci];
410     entropy->last_dc_val[ci] = temp2;
411 
412     /* Encode the DC coefficient difference per section G.1.2.1 */
413     temp2 = temp;
414     if (temp < 0) {
415       temp = -temp;		/* temp is abs value of input */
416       /* For a negative input, want temp2 = bitwise complement of abs(input) */
417       /* This code assumes we are on a two's complement machine */
418       temp2--;
419     }
420 
421     /* Find the number of bits needed for the magnitude of the coefficient */
422     nbits = 0;
423     while (temp) {
424       nbits++;
425       temp >>= 1;
426     }
427     /* Check for out-of-range coefficient values.
428      * Since we're encoding a difference, the range limit is twice as much.
429      */
430     if (nbits > MAX_COEF_BITS+1)
431       ERREXIT(cinfo, JERR_BAD_DCT_COEF);
432 
433     /* Count/emit the Huffman-coded symbol for the number of bits */
434     emit_symbol(entropy, compptr->dc_tbl_no, nbits);
435 
436     /* Emit that number of bits of the value, if positive, */
437     /* or the complement of its magnitude, if negative. */
438     if (nbits)			/* emit_bits rejects calls with size 0 */
439       emit_bits(entropy, (unsigned int) temp2, nbits);
440   }
441 
442   cinfo->dest->next_output_byte = entropy->next_output_byte;
443   cinfo->dest->free_in_buffer = entropy->free_in_buffer;
444 
445   /* Update restart-interval state too */
446   if (cinfo->restart_interval) {
447     if (entropy->restarts_to_go == 0) {
448       entropy->restarts_to_go = cinfo->restart_interval;
449       entropy->next_restart_num++;
450       entropy->next_restart_num &= 7;
451     }
452     entropy->restarts_to_go--;
453   }
454 
455   return TRUE;
456 }
457 
458 
459 /*
460  * MCU encoding for AC initial scan (either spectral selection,
461  * or first pass of successive approximation).
462  */
463 
464 METHODDEF(boolean)
encode_mcu_AC_first(j_compress_ptr cinfo,JBLOCKROW * MCU_data)465 encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
466 {
467   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
468   register int temp, temp2;
469   register int nbits;
470   register int r, k;
471   int Se = cinfo->Se;
472   int Al = cinfo->Al;
473   JBLOCKROW block;
474 
475   entropy->next_output_byte = cinfo->dest->next_output_byte;
476   entropy->free_in_buffer = cinfo->dest->free_in_buffer;
477 
478   /* Emit restart marker if needed */
479   if (cinfo->restart_interval)
480     if (entropy->restarts_to_go == 0)
481       emit_restart(entropy, entropy->next_restart_num);
482 
483   /* Encode the MCU data block */
484   block = MCU_data[0];
485 
486   /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */
487 
488   r = 0;			/* r = run length of zeros */
489 
490   for (k = cinfo->Ss; k <= Se; k++) {
491     if ((temp = (*block)[jpeg_natural_order[k]]) == 0) {
492       r++;
493       continue;
494     }
495     /* We must apply the point transform by Al.  For AC coefficients this
496      * is an integer division with rounding towards 0.  To do this portably
497      * in C, we shift after obtaining the absolute value; so the code is
498      * interwoven with finding the abs value (temp) and output bits (temp2).
499      */
500     if (temp < 0) {
501       temp = -temp;		/* temp is abs value of input */
502       temp >>= Al;		/* apply the point transform */
503       /* For a negative coef, want temp2 = bitwise complement of abs(coef) */
504       temp2 = ~temp;
505     } else {
506       temp >>= Al;		/* apply the point transform */
507       temp2 = temp;
508     }
509     /* Watch out for case that nonzero coef is zero after point transform */
510     if (temp == 0) {
511       r++;
512       continue;
513     }
514 
515     /* Emit any pending EOBRUN */
516     if (entropy->EOBRUN > 0)
517       emit_eobrun(entropy);
518     /* if run length > 15, must emit special run-length-16 codes (0xF0) */
519     while (r > 15) {
520       emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
521       r -= 16;
522     }
523 
524     /* Find the number of bits needed for the magnitude of the coefficient */
525     nbits = 1;			/* there must be at least one 1 bit */
526     while ((temp >>= 1))
527       nbits++;
528     /* Check for out-of-range coefficient values */
529     if (nbits > MAX_COEF_BITS)
530       ERREXIT(cinfo, JERR_BAD_DCT_COEF);
531 
532     /* Count/emit Huffman symbol for run length / number of bits */
533     emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);
534 
535     /* Emit that number of bits of the value, if positive, */
536     /* or the complement of its magnitude, if negative. */
537     emit_bits(entropy, (unsigned int) temp2, nbits);
538 
539     r = 0;			/* reset zero run length */
540   }
541 
542   if (r > 0) {			/* If there are trailing zeroes, */
543     entropy->EOBRUN++;		/* count an EOB */
544     if (entropy->EOBRUN == 0x7FFF)
545       emit_eobrun(entropy);	/* force it out to avoid overflow */
546   }
547 
548   cinfo->dest->next_output_byte = entropy->next_output_byte;
549   cinfo->dest->free_in_buffer = entropy->free_in_buffer;
550 
551   /* Update restart-interval state too */
552   if (cinfo->restart_interval) {
553     if (entropy->restarts_to_go == 0) {
554       entropy->restarts_to_go = cinfo->restart_interval;
555       entropy->next_restart_num++;
556       entropy->next_restart_num &= 7;
557     }
558     entropy->restarts_to_go--;
559   }
560 
561   return TRUE;
562 }
563 
564 
565 /*
566  * MCU encoding for DC successive approximation refinement scan.
567  * Note: we assume such scans can be multi-component, although the spec
568  * is not very clear on the point.
569  */
570 
571 METHODDEF(boolean)
encode_mcu_DC_refine(j_compress_ptr cinfo,JBLOCKROW * MCU_data)572 encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
573 {
574   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
575   register int temp;
576   int blkn;
577   int Al = cinfo->Al;
578   JBLOCKROW block;
579 
580   entropy->next_output_byte = cinfo->dest->next_output_byte;
581   entropy->free_in_buffer = cinfo->dest->free_in_buffer;
582 
583   /* Emit restart marker if needed */
584   if (cinfo->restart_interval)
585     if (entropy->restarts_to_go == 0)
586       emit_restart(entropy, entropy->next_restart_num);
587 
588   /* Encode the MCU data blocks */
589   for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
590     block = MCU_data[blkn];
591 
592     /* We simply emit the Al'th bit of the DC coefficient value. */
593     temp = (*block)[0];
594     emit_bits(entropy, (unsigned int) (temp >> Al), 1);
595   }
596 
597   cinfo->dest->next_output_byte = entropy->next_output_byte;
598   cinfo->dest->free_in_buffer = entropy->free_in_buffer;
599 
600   /* Update restart-interval state too */
601   if (cinfo->restart_interval) {
602     if (entropy->restarts_to_go == 0) {
603       entropy->restarts_to_go = cinfo->restart_interval;
604       entropy->next_restart_num++;
605       entropy->next_restart_num &= 7;
606     }
607     entropy->restarts_to_go--;
608   }
609 
610   return TRUE;
611 }
612 
613 
614 /*
615  * MCU encoding for AC successive approximation refinement scan.
616  */
617 
618 METHODDEF(boolean)
encode_mcu_AC_refine(j_compress_ptr cinfo,JBLOCKROW * MCU_data)619 encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
620 {
621   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
622   register int temp;
623   register int r, k;
624   int EOB;
625   char *BR_buffer;
626   unsigned int BR;
627   int Se = cinfo->Se;
628   int Al = cinfo->Al;
629   JBLOCKROW block;
630   int absvalues[DCTSIZE2];
631 
632   entropy->next_output_byte = cinfo->dest->next_output_byte;
633   entropy->free_in_buffer = cinfo->dest->free_in_buffer;
634 
635   /* Emit restart marker if needed */
636   if (cinfo->restart_interval)
637     if (entropy->restarts_to_go == 0)
638       emit_restart(entropy, entropy->next_restart_num);
639 
640   /* Encode the MCU data block */
641   block = MCU_data[0];
642 
643   /* It is convenient to make a pre-pass to determine the transformed
644    * coefficients' absolute values and the EOB position.
645    */
646   EOB = 0;
647   for (k = cinfo->Ss; k <= Se; k++) {
648     temp = (*block)[jpeg_natural_order[k]];
649     /* We must apply the point transform by Al.  For AC coefficients this
650      * is an integer division with rounding towards 0.  To do this portably
651      * in C, we shift after obtaining the absolute value.
652      */
653     if (temp < 0)
654       temp = -temp;		/* temp is abs value of input */
655     temp >>= Al;		/* apply the point transform */
656     absvalues[k] = temp;	/* save abs value for main pass */
657     if (temp == 1)
658       EOB = k;			/* EOB = index of last newly-nonzero coef */
659   }
660 
661   /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */
662 
663   r = 0;			/* r = run length of zeros */
664   BR = 0;			/* BR = count of buffered bits added now */
665   BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */
666 
667   for (k = cinfo->Ss; k <= Se; k++) {
668     if ((temp = absvalues[k]) == 0) {
669       r++;
670       continue;
671     }
672 
673     /* Emit any required ZRLs, but not if they can be folded into EOB */
674     while (r > 15 && k <= EOB) {
675       /* emit any pending EOBRUN and the BE correction bits */
676       emit_eobrun(entropy);
677       /* Emit ZRL */
678       emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
679       r -= 16;
680       /* Emit buffered correction bits that must be associated with ZRL */
681       emit_buffered_bits(entropy, BR_buffer, BR);
682       BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
683       BR = 0;
684     }
685 
686     /* If the coef was previously nonzero, it only needs a correction bit.
687      * NOTE: a straight translation of the spec's figure G.7 would suggest
688      * that we also need to test r > 15.  But if r > 15, we can only get here
689      * if k > EOB, which implies that this coefficient is not 1.
690      */
691     if (temp > 1) {
692       /* The correction bit is the next bit of the absolute value. */
693       BR_buffer[BR++] = (char) (temp & 1);
694       continue;
695     }
696 
697     /* Emit any pending EOBRUN and the BE correction bits */
698     emit_eobrun(entropy);
699 
700     /* Count/emit Huffman symbol for run length / number of bits */
701     emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);
702 
703     /* Emit output bit for newly-nonzero coef */
704     temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1;
705     emit_bits(entropy, (unsigned int) temp, 1);
706 
707     /* Emit buffered correction bits that must be associated with this code */
708     emit_buffered_bits(entropy, BR_buffer, BR);
709     BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
710     BR = 0;
711     r = 0;			/* reset zero run length */
712   }
713 
714   if (r > 0 || BR > 0) {	/* If there are trailing zeroes, */
715     entropy->EOBRUN++;		/* count an EOB */
716     entropy->BE += BR;		/* concat my correction bits to older ones */
717     /* We force out the EOB if we risk either:
718      * 1. overflow of the EOB counter;
719      * 2. overflow of the correction bit buffer during the next MCU.
720      */
721     if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1))
722       emit_eobrun(entropy);
723   }
724 
725   cinfo->dest->next_output_byte = entropy->next_output_byte;
726   cinfo->dest->free_in_buffer = entropy->free_in_buffer;
727 
728   /* Update restart-interval state too */
729   if (cinfo->restart_interval) {
730     if (entropy->restarts_to_go == 0) {
731       entropy->restarts_to_go = cinfo->restart_interval;
732       entropy->next_restart_num++;
733       entropy->next_restart_num &= 7;
734     }
735     entropy->restarts_to_go--;
736   }
737 
738   return TRUE;
739 }
740 
741 
742 /*
743  * Finish up at the end of a Huffman-compressed progressive scan.
744  */
745 
746 METHODDEF(void)
finish_pass_phuff(j_compress_ptr cinfo)747 finish_pass_phuff (j_compress_ptr cinfo)
748 {
749   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
750 
751   entropy->next_output_byte = cinfo->dest->next_output_byte;
752   entropy->free_in_buffer = cinfo->dest->free_in_buffer;
753 
754   /* Flush out any buffered data */
755   emit_eobrun(entropy);
756   flush_bits(entropy);
757 
758   cinfo->dest->next_output_byte = entropy->next_output_byte;
759   cinfo->dest->free_in_buffer = entropy->free_in_buffer;
760 }
761 
762 
763 /*
764  * Finish up a statistics-gathering pass and create the new Huffman tables.
765  */
766 
767 METHODDEF(void)
finish_pass_gather_phuff(j_compress_ptr cinfo)768 finish_pass_gather_phuff (j_compress_ptr cinfo)
769 {
770   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
771   boolean is_DC_band;
772   int ci, tbl;
773   jpeg_component_info * compptr;
774   JHUFF_TBL **htblptr;
775   boolean did[NUM_HUFF_TBLS];
776 
777   /* Flush out buffered data (all we care about is counting the EOB symbol) */
778   emit_eobrun(entropy);
779 
780   is_DC_band = (cinfo->Ss == 0);
781 
782   /* It's important not to apply jpeg_gen_optimal_table more than once
783    * per table, because it clobbers the input frequency counts!
784    */
785   MEMZERO(did, SIZEOF(did));
786 
787   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
788     compptr = cinfo->cur_comp_info[ci];
789     if (is_DC_band) {
790       if (cinfo->Ah != 0)	/* DC refinement needs no table */
791 	continue;
792       tbl = compptr->dc_tbl_no;
793     } else {
794       tbl = compptr->ac_tbl_no;
795     }
796     if (! did[tbl]) {
797       if (is_DC_band)
798         htblptr = & cinfo->dc_huff_tbl_ptrs[tbl];
799       else
800         htblptr = & cinfo->ac_huff_tbl_ptrs[tbl];
801       if (*htblptr == NULL)
802         *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
803       jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]);
804       did[tbl] = TRUE;
805     }
806   }
807 }
808 
809 
810 /*
811  * Module initialization routine for progressive Huffman entropy encoding.
812  */
813 
814 GLOBAL(void)
jinit_phuff_encoder(j_compress_ptr cinfo)815 jinit_phuff_encoder (j_compress_ptr cinfo)
816 {
817   phuff_entropy_ptr entropy;
818   int i;
819 
820   entropy = (phuff_entropy_ptr)
821     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
822 				SIZEOF(phuff_entropy_encoder));
823   cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
824   entropy->pub.start_pass = start_pass_phuff;
825 
826   /* Mark tables unallocated */
827   for (i = 0; i < NUM_HUFF_TBLS; i++) {
828     entropy->derived_tbls[i] = NULL;
829     entropy->count_ptrs[i] = NULL;
830   }
831   entropy->bit_buffer = NULL;	/* needed only in AC refinement scan */
832 }
833 
834 #endif /* C_PROGRESSIVE_SUPPORTED */
835 
836 #endif //_FX_JPEG_TURBO_
837