1  /********************************************************************** <BR>


2  This file is part of Crack dot Com's free source code release of


3  Golgotha. <a href="http://www.crack.com/golgotha_release"> <BR> for


4  information about compiling & licensing issues visit this URL</a>


5  <PRE> If that doesn't help, contact Jonathan Clark at


6  golgotha_source@usa.net (Subject should have "GOLG" in it)


7  ***********************************************************************/


8 


9  /*


10  * jdphuff.c


11  *


12  * Copyright (C) 19951996, Thomas G. Lane.


13  * This file is part of the Independent JPEG Group's software.


14  * For conditions of distribution and use, see the accompanying README file.


15  *


16  * This file contains Huffman entropy decoding routines for progressive JPEG.


17  *


18  * Much of the complexity here has to do with supporting input suspension.


19  * If the data source module demands suspension, we want to be able to back


20  * up to the start of the current MCU. To do this, we copy state variables


21  * into local working storage, and update them back to the permanent


22  * storage only upon successful completion of an MCU.


23  */


24 


25  #define JPEG_INTERNALS


26  #include "loaders/jpg/jinclude.h"


27  #include "loaders/jpg/jpeglib.h"


28  #include "loaders/jpg/jdhuff.h" /* Declarations shared with jdhuff.c */


29 


30 


31  #ifdef D_PROGRESSIVE_SUPPORTED


32 


33  /*


34  * Expanded entropy decoder object for progressive Huffman decoding.


35  *


36  * The savable_state subrecord contains fields that change within an MCU,


37  * but must not be updated permanently until we complete the MCU.


38  */


39 


40  typedef struct {


41  unsigned int EOBRUN; /* remaining EOBs in EOBRUN */


42  int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */


43  } savable_state;


44 


45  /* This macro is to work around compilers with missing or broken


46  * structure assignment. You'll need to fix this code if you have


47  * such a compiler and you change MAX_COMPS_IN_SCAN.


48  */


49 


50  #ifndef NO_STRUCT_ASSIGN


51  #define ASSIGN_STATE(dest,src) ((dest) = (src))


52  #else


53  #if MAX_COMPS_IN_SCAN == 4


54  #define ASSIGN_STATE(dest,src) \


55  ((dest).EOBRUN = (src).EOBRUN, \


56  (dest).last_dc_val[0] = (src).last_dc_val[0], \


57  (dest).last_dc_val[1] = (src).last_dc_val[1], \


58  (dest).last_dc_val[2] = (src).last_dc_val[2], \


59  (dest).last_dc_val[3] = (src).last_dc_val[3])


60  #endif


61  #endif


62 


63 


64  typedef struct {


65  struct jpeg_entropy_decoder pub; /* public fields */


66 


67  /* These fields are loaded into local variables at start of each MCU.


68  * In case of suspension, we exit WITHOUT updating them.


69  */


70  bitread_perm_state bitstate; /* Bit buffer at start of MCU */


71  savable_state saved; /* Other state at start of MCU */


72 


73  /* These fields are NOT loaded into local working state. */


74  unsigned int restarts_to_go; /* MCUs left in this restart interval */


75 


76  /* Pointers to derived tables (these workspaces have image lifespan) */


77  d_derived_tbl * derived_tbls[NUM_HUFF_TBLS];


78 


79  d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */


80  } phuff_entropy_decoder;


81 


82  typedef phuff_entropy_decoder * phuff_entropy_ptr;


83 


84  /* Forward declarations */


85  METHODDEF(boolean) decode_mcu_DC_first JPP((j_decompress_ptr cinfo,


86  JBLOCKROW *MCU_data));


87  METHODDEF(boolean) decode_mcu_AC_first JPP((j_decompress_ptr cinfo,


88  JBLOCKROW *MCU_data));


89  METHODDEF(boolean) decode_mcu_DC_refine JPP((j_decompress_ptr cinfo,


90  JBLOCKROW *MCU_data));


91  METHODDEF(boolean) decode_mcu_AC_refine JPP((j_decompress_ptr cinfo,


92  JBLOCKROW *MCU_data));


93 


94 


95  /*


96  * Initialize for a Huffmancompressed scan.


97  */


98 


99  METHODDEF(void)


100  start_pass_phuff_decoder (j_decompress_ptr cinfo)


101  {


102  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo>entropy;


103  boolean is_DC_band, bad;


104  int ci, coefi, tbl;


105  int *coef_bit_ptr;


106  jpeg_component_info * compptr;


107 


108  is_DC_band = (cinfo>Ss == 0);


109 


110  /* Validate scan parameters */


111  bad = FALSE;


112  if (is_DC_band) {


113  if (cinfo>Se != 0)


114  bad = TRUE;


115  } else {


116  /* need not check Ss/Se < 0 since they came from unsigned bytes */


117  if (cinfo>Ss > cinfo>Se  cinfo>Se >= DCTSIZE2)


118  bad = TRUE;


119  /* AC scans may have only one component */


120  if (cinfo>comps_in_scan != 1)


121  bad = TRUE;


122  }


123  if (cinfo>Ah != 0) {


124  /* Successive approximation refinement scan: must have Al = Ah1. */


125  if (cinfo>Al != cinfo>Ah1)


126  bad = TRUE;


127  }


128  if (cinfo>Al > 13) /* need not check for < 0 */


129  bad = TRUE;


130  if (bad)


131  ERREXIT4(cinfo, JERR_BAD_PROGRESSION,


132  cinfo>Ss, cinfo>Se, cinfo>Ah, cinfo>Al);


133  /* Update progression status, and verify that scan order is legal.


134  * Note that interscan inconsistencies are treated as warnings


135  * not fatal errors ... not clear if this is right way to behave.


136  */


137  for (ci = 0; ci < cinfo>comps_in_scan; ci++) {


138  int cindex = cinfo>cur_comp_info[ci]>component_index;


139  coef_bit_ptr = & cinfo>coef_bits[cindex][0];


140  if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */


141  WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);


142  for (coefi = cinfo>Ss; coefi <= cinfo>Se; coefi++) {


143  int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];


144  if (cinfo>Ah != expected)


145  WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);


146  coef_bit_ptr[coefi] = cinfo>Al;


147  }


148  }


149 


150  /* Select MCU decoding routine */


151  if (cinfo>Ah == 0) {


152  if (is_DC_band)


153  entropy>pub.decode_mcu = decode_mcu_DC_first;


154  else


155  entropy>pub.decode_mcu = decode_mcu_AC_first;


156  } else {


157  if (is_DC_band)


158  entropy>pub.decode_mcu = decode_mcu_DC_refine;


159  else


160  entropy>pub.decode_mcu = decode_mcu_AC_refine;


161  }


162 


163  for (ci = 0; ci < cinfo>comps_in_scan; ci++) {


164  compptr = cinfo>cur_comp_info[ci];


165  /* Make sure requested tables are present, and compute derived tables.


166  * We may build same derived table more than once, but it's not expensive.


167  */


168  if (is_DC_band) {


169  if (cinfo>Ah == 0) { /* DC refinement needs no table */


170  tbl = compptr>dc_tbl_no;


171  if (tbl < 0  tbl >= NUM_HUFF_TBLS 


172  cinfo>dc_huff_tbl_ptrs[tbl] == NULL)


173  ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);


174  jpeg_make_d_derived_tbl(cinfo, cinfo>dc_huff_tbl_ptrs[tbl],


175  & entropy>derived_tbls[tbl]);


176  }


177  } else {


178  tbl = compptr>ac_tbl_no;


179  if (tbl < 0  tbl >= NUM_HUFF_TBLS 


180  cinfo>ac_huff_tbl_ptrs[tbl] == NULL)


181  ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);


182  jpeg_make_d_derived_tbl(cinfo, cinfo>ac_huff_tbl_ptrs[tbl],


183  & entropy>derived_tbls[tbl]);


184  /* remember the single active table */


185  entropy>ac_derived_tbl = entropy>derived_tbls[tbl];


186  }


187  /* Initialize DC predictions to 0 */


188  entropy>saved.last_dc_val[ci] = 0;


189  }


190 


191  /* Initialize bitread state variables */


192  entropy>bitstate.bits_left = 0;


193  entropy>bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */


194  entropy>bitstate.printed_eod = FALSE;


195 


196  /* Initialize private state variables */


197  entropy>saved.EOBRUN = 0;


198 


199  /* Initialize restart counter */


200  entropy>restarts_to_go = cinfo>restart_interval;


201  }


202 


203 


204  /*


205  * Figure F.12: extend sign bit.


206  * On some machines, a shift and add will be faster than a table lookup.


207  */


208 


209  #ifdef AVOID_TABLES


210 


211  #define HUFF_EXTEND(x,s) ((x) < (1<<((s)1)) ? (x) + (((1)<<(s)) + 1) : (x))


212 


213  #else


214 


215  #define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))


216 


217  static const int extend_test[16] = /* entry n is 2**(n1) */


218  { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,


219  0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };


220 


221  static const int extend_offset[16] = /* entry n is (1 << n) + 1 */


222  { 0, ((1)<<1) + 1, ((1)<<2) + 1, ((1)<<3) + 1, ((1)<<4) + 1,


223  ((1)<<5) + 1, ((1)<<6) + 1, ((1)<<7) + 1, ((1)<<8) + 1,


224  ((1)<<9) + 1, ((1)<<10) + 1, ((1)<<11) + 1, ((1)<<12) + 1,


225  ((1)<<13) + 1, ((1)<<14) + 1, ((1)<<15) + 1 };


226 


227  #endif /* AVOID_TABLES */


228 


229 


230  /*


231  * Check for a restart marker & resynchronize decoder.


232  * Returns FALSE if must suspend.


233  */


234 


235  LOCAL(boolean)


236  process_restart (j_decompress_ptr cinfo)


237  {


238  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo>entropy;


239  int ci;


240 


241  /* Throw away any unused bits remaining in bit buffer; */


242  /* include any full bytes in next_marker's count of discarded bytes */


243  cinfo>marker>discarded_bytes += entropy>bitstate.bits_left / 8;


244  entropy>bitstate.bits_left = 0;


245 


246  /* Advance past the RSTn marker */


247  if (! (*cinfo>marker>read_restart_marker) (cinfo))


248  return FALSE;


249 


250  /* Reinitialize DC predictions to 0 */


251  for (ci = 0; ci < cinfo>comps_in_scan; ci++)


252  entropy>saved.last_dc_val[ci] = 0;


253  /* Reinit EOB run count, too */


254  entropy>saved.EOBRUN = 0;


255 


256  /* Reset restart counter */


257  entropy>restarts_to_go = cinfo>restart_interval;


258 


259  /* Next segment can get another outofdata warning */


260  entropy>bitstate.printed_eod = FALSE;


261 


262  return TRUE;


263  }


264 


265 


266  /*


267  * Huffman MCU decoding.


268  * Each of these routines decodes and returns one MCU's worth of


269  * Huffmancompressed coefficients.


270  * The coefficients are reordered from zigzag order into natural array order,


271  * but are not dequantized.


272  *


273  * The i'th block of the MCU is stored into the block pointed to by


274  * MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.


275  *


276  * We return FALSE if data source requested suspension. In that case no


277  * changes have been made to permanent state. (Exception: some output


278  * coefficients may already have been assigned. This is harmless for


279  * spectral selection, since we'll just reassign them on the next call.


280  * Successive approximation AC refinement has to be more careful, however.)


281  */


282 


283  /*


284  * MCU decoding for DC initial scan (either spectral selection,


285  * or first pass of successive approximation).


286  */


287 


288  METHODDEF(boolean)


289  decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)


290  {


291  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo>entropy;


292  int Al = cinfo>Al;


293  register int s, r;


294  int blkn, ci;


295  JBLOCKROW block;


296  BITREAD_STATE_VARS;


297  savable_state state;


298  d_derived_tbl * tbl;


299  jpeg_component_info * compptr;


300 


301  /* Process restart marker if needed; may have to suspend */


302  if (cinfo>restart_interval) {


303  if (entropy>restarts_to_go == 0)


304  if (! process_restart(cinfo))


305  return FALSE;


306  }


307 


308  /* Load up working state */


309  BITREAD_LOAD_STATE(cinfo,entropy>bitstate);


310  ASSIGN_STATE(state, entropy>saved);


311 


312  /* Outer loop handles each block in the MCU */


313 


314  for (blkn = 0; blkn < cinfo>blocks_in_MCU; blkn++) {


315  block = MCU_data[blkn];


316  ci = cinfo>MCU_membership[blkn];


317  compptr = cinfo>cur_comp_info[ci];


318  tbl = entropy>derived_tbls[compptr>dc_tbl_no];


319 


320  /* Decode a single block's worth of coefficients */


321 


322  /* Section F.2.2.1: decode the DC coefficient difference */


323  HUFF_DECODE(s, br_state, tbl, return FALSE, label1);


324  if (s) {


325  CHECK_BIT_BUFFER(br_state, s, return FALSE);


326  r = GET_BITS(s);


327  s = HUFF_EXTEND(r, s);


328  }


329 


330  /* Convert DC difference to actual value, update last_dc_val */


331  s += state.last_dc_val[ci];


332  state.last_dc_val[ci] = s;


333  /* Scale and output the DC coefficient (assumes jpeg_natural_order[0]=0) */


334  (*block)[0] = (JCOEF) (s << Al);


335  }


336 


337  /* Completed MCU, so update state */


338  BITREAD_SAVE_STATE(cinfo,entropy>bitstate);


339  ASSIGN_STATE(entropy>saved, state);


340 


341  /* Account for restart interval (noop if not using restarts) */


342  entropy>restarts_to_go;


343 


344  return TRUE;


345  }


346 


347 


348  /*


349  * MCU decoding for AC initial scan (either spectral selection,


350  * or first pass of successive approximation).


351  */


352 


353  METHODDEF(boolean)


354  decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)


355  {


356  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo>entropy;


357  int Se = cinfo>Se;


358  int Al = cinfo>Al;


359  register int s, k, r;


360  unsigned int EOBRUN;


361  JBLOCKROW block;


362  BITREAD_STATE_VARS;


363  d_derived_tbl * tbl;


364 


365  /* Process restart marker if needed; may have to suspend */


366  if (cinfo>restart_interval) {


367  if (entropy>restarts_to_go == 0)


368  if (! process_restart(cinfo))


369  return FALSE;


370  }


371 


372  /* Load up working state.


373  * We can avoid loading/saving bitread state if in an EOB run.


374  */


375  EOBRUN = entropy>saved.EOBRUN; /* only part of saved state we care about */


376 


377  /* There is always only one block per MCU */


378 


379  if (EOBRUN > 0) /* if it's a band of zeroes... */


380  EOBRUN; /* ...process it now (we do nothing) */


381  else {


382  BITREAD_LOAD_STATE(cinfo,entropy>bitstate);


383  block = MCU_data[0];


384  tbl = entropy>ac_derived_tbl;


385 


386  for (k = cinfo>Ss; k <= Se; k++) {


387  HUFF_DECODE(s, br_state, tbl, return FALSE, label2);


388  r = s >> 4;


389  s &= 15;


390  if (s) {


391  k += r;


392  CHECK_BIT_BUFFER(br_state, s, return FALSE);


393  r = GET_BITS(s);


394  s = HUFF_EXTEND(r, s);


395  /* Scale and output coefficient in natural (dezigzagged) order */


396  (*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al);


397  } else {


398  if (r == 15) { /* ZRL */


399  k += 15; /* skip 15 zeroes in band */


400  } else { /* EOBr, run length is 2^r + appended bits */


401  EOBRUN = 1 << r;


402  if (r) { /* EOBr, r > 0 */


403  CHECK_BIT_BUFFER(br_state, r, return FALSE);


404  r = GET_BITS(r);


405  EOBRUN += r;


406  }


407  EOBRUN; /* this band is processed at this moment */


408  break; /* force endofband */


409  }


410  }


411  }


412 


413  BITREAD_SAVE_STATE(cinfo,entropy>bitstate);


414  }


415 


416  /* Completed MCU, so update state */


417  entropy>saved.EOBRUN = EOBRUN; /* only part of saved state we care about */


418 


419  /* Account for restart interval (noop if not using restarts) */


420  entropy>restarts_to_go;


421 


422  return TRUE;


423  }


424 


425 


426  /*


427  * MCU decoding for DC successive approximation refinement scan.


428  * Note: we assume such scans can be multicomponent, although the spec


429  * is not very clear on the point.


430  */


431 


432  METHODDEF(boolean)


433  decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)


434  {


435  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo>entropy;


436  int p1 = 1 << cinfo>Al; /* 1 in the bit position being coded */


437  int blkn;


438  JBLOCKROW block;


439  BITREAD_STATE_VARS;


440 


441  /* Process restart marker if needed; may have to suspend */


442  if (cinfo>restart_interval) {


443  if (entropy>restarts_to_go == 0)


444  if (! process_restart(cinfo))


445  return FALSE;


446  }


447 


448  /* Load up working state */


449  BITREAD_LOAD_STATE(cinfo,entropy>bitstate);


450 


451  /* Outer loop handles each block in the MCU */


452 


453  for (blkn = 0; blkn < cinfo>blocks_in_MCU; blkn++) {


454  block = MCU_data[blkn];


455 


456  /* Encoded data is simply the next bit of the two'scomplement DC value */


457  CHECK_BIT_BUFFER(br_state, 1, return FALSE);


458  if (GET_BITS(1))


459  (*block)[0] = p1;


460  /* Note: since we use =, repeating the assignment later is safe */


461  }


462 


463  /* Completed MCU, so update state */


464  BITREAD_SAVE_STATE(cinfo,entropy>bitstate);


465 


466  /* Account for restart interval (noop if not using restarts) */


467  entropy>restarts_to_go;


468 


469  return TRUE;


470  }


471 


472 


473  /*


474  * MCU decoding for AC successive approximation refinement scan.


475  */


476 


477  METHODDEF(boolean)


478  decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)


479  {


480  phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo>entropy;


481  int Se = cinfo>Se;


482  int p1 = 1 << cinfo>Al; /* 1 in the bit position being coded */


483  int m1 = (1) << cinfo>Al; /* 1 in the bit position being coded */


484  register int s, k, r;


485  unsigned int EOBRUN;


486  JBLOCKROW block;


487  JCOEFPTR thiscoef;


488  BITREAD_STATE_VARS;


489  d_derived_tbl * tbl;


490  int num_newnz;


491  int newnz_pos[DCTSIZE2];


492 


493  /* Process restart marker if needed; may have to suspend */


494  if (cinfo>restart_interval) {


495  if (entropy>restarts_to_go == 0)


496  if (! process_restart(cinfo))


497  return FALSE;


498  }


499 


500  /* Load up working state */


501  BITREAD_LOAD_STATE(cinfo,entropy>bitstate);


502  EOBRUN = entropy>saved.EOBRUN; /* only part of saved state we care about */


503 


504  /* There is always only one block per MCU */


505  block = MCU_data[0];


506  tbl = entropy>ac_derived_tbl;


507 


508  /* If we are forced to suspend, we must undo the assignments to any newly


509  * nonzero coefficients in the block, because otherwise we'd get confused


510  * next time about which coefficients were already nonzero.


511  * But we need not undo addition of bits to alreadynonzero coefficients;


512  * instead, we can test the current bit position to see if we already did it.


513  */


514  num_newnz = 0;


515 


516  /* initialize coefficient loop counter to start of band */


517  k = cinfo>Ss;


518 


519  if (EOBRUN == 0) {


520  for (; k <= Se; k++) {


521  HUFF_DECODE(s, br_state, tbl, goto undoit, label3);


522  r = s >> 4;


523  s &= 15;


524  if (s) {


525  if (s != 1) /* size of new coef should always be 1 */


526  WARNMS(cinfo, JWRN_HUFF_BAD_CODE);


527  CHECK_BIT_BUFFER(br_state, 1, goto undoit);


528  if (GET_BITS(1))


529  s = p1; /* newly nonzero coef is positive */


530  else


531  s = m1; /* newly nonzero coef is negative */


532  } else {


533  if (r != 15) {


534  EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */


535  if (r) {


536  CHECK_BIT_BUFFER(br_state, r, goto undoit);


537  r = GET_BITS(r);


538  EOBRUN += r;


539  }


540  break; /* rest of block is handled by EOB logic */


541  }


542  /* note s = 0 for processing ZRL */


543  }


544  /* Advance over alreadynonzero coefs and r stillzero coefs,


545  * appending correction bits to the nonzeroes. A correction bit is 1


546  * if the absolute value of the coefficient must be increased.


547  */


548  do {


549  thiscoef = *block + jpeg_natural_order[k];


550  if (*thiscoef != 0) {


551  CHECK_BIT_BUFFER(br_state, 1, goto undoit);


552  if (GET_BITS(1)) {


553  if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */


554  if (*thiscoef >= 0)


555  *thiscoef += p1;


556  else


557  *thiscoef += m1;


558  }


559  }


560  } else {


561  if (r < 0)


562  break; /* reached target zero coefficient */


563  }


564  k++;


565  } while (k <= Se);


566  if (s) {


567  int pos = jpeg_natural_order[k];


568  /* Output newly nonzero coefficient */


569  (*block)[pos] = (JCOEF) s;


570  /* Remember its position in case we have to suspend */


571  newnz_pos[num_newnz++] = pos;


572  }


573  }


574  }


575 


576  if (EOBRUN > 0) {


577  /* Scan any remaining coefficient positions after the endofband


578  * (the last newly nonzero coefficient, if any). Append a correction


579  * bit to each alreadynonzero coefficient. A correction bit is 1


580  * if the absolute value of the coefficient must be increased.


581  */


582  for (; k <= Se; k++) {


583  thiscoef = *block + jpeg_natural_order[k];


584  if (*thiscoef != 0) {


585  CHECK_BIT_BUFFER(br_state, 1, goto undoit);


586  if (GET_BITS(1)) {


587  if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */


588  if (*thiscoef >= 0)


589  *thiscoef += p1;


590  else


591  *thiscoef += m1;


592  }


593  }


594  }


595  }


596  /* Count one block completed in EOB run */


597  EOBRUN;


598  }


599 


600  /* Completed MCU, so update state */


601  BITREAD_SAVE_STATE(cinfo,entropy>bitstate);


602  entropy>saved.EOBRUN = EOBRUN; /* only part of saved state we care about */


603 


604  /* Account for restart interval (noop if not using restarts) */


605  entropy>restarts_to_go;


606 


607  return TRUE;


608 


609  undoit:


610  /* Rezero any output coefficients that we made newly nonzero */


611  while (num_newnz > 0)


612  (*block)[newnz_pos[num_newnz]] = 0;


613 


614  return FALSE;


615  }


616 


617 


618  /*


619  * Module initialization routine for progressive Huffman entropy decoding.


620  */


621 


622  GLOBAL(void)


623  jinit_phuff_decoder (j_decompress_ptr cinfo)


624  {


625  phuff_entropy_ptr entropy;


626  int *coef_bit_ptr;


627  int ci, i;


628 


629  entropy = (phuff_entropy_ptr)


630  (*cinfo>mem>alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,


631  SIZEOF(phuff_entropy_decoder));


632  cinfo>entropy = (struct jpeg_entropy_decoder *) entropy;


633  entropy>pub.start_pass = start_pass_phuff_decoder;


634 


635  /* Mark derived tables unallocated */


636  for (i = 0; i < NUM_HUFF_TBLS; i++) {


637  entropy>derived_tbls[i] = NULL;


638  }


639 


640  /* Create progression status table */


641  cinfo>coef_bits = (int (*)[DCTSIZE2])


642  (*cinfo>mem>alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,


643  cinfo>num_components*DCTSIZE2*SIZEOF(int));


644  coef_bit_ptr = & cinfo>coef_bits[0][0];


645  for (ci = 0; ci < cinfo>num_components; ci++)


646  for (i = 0; i < DCTSIZE2; i++)


647  *coef_bit_ptr++ = 1;


648  }


649 


650  #endif /* D_PROGRESSIVE_SUPPORTED */

