nuclear@2: /*
nuclear@2:  * jdphuff.c
nuclear@2:  *
nuclear@2:  * Copyright (C) 1995-1997, Thomas G. Lane.
nuclear@2:  * This file is part of the Independent JPEG Group's software.
nuclear@2:  * For conditions of distribution and use, see the accompanying README file.
nuclear@2:  *
nuclear@2:  * This file contains Huffman entropy decoding routines for progressive JPEG.
nuclear@2:  *
nuclear@2:  * Much of the complexity here has to do with supporting input suspension.
nuclear@2:  * If the data source module demands suspension, we want to be able to back
nuclear@2:  * up to the start of the current MCU.  To do this, we copy state variables
nuclear@2:  * into local working storage, and update them back to the permanent
nuclear@2:  * storage only upon successful completion of an MCU.
nuclear@2:  */
nuclear@2: 
nuclear@2: #define JPEG_INTERNALS
nuclear@2: #include "jinclude.h"
nuclear@2: #include "jpeglib.h"
nuclear@2: #include "jdhuff.h"		/* Declarations shared with jdhuff.c */
nuclear@2: 
nuclear@2: 
nuclear@2: #ifdef D_PROGRESSIVE_SUPPORTED
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Expanded entropy decoder object for progressive Huffman decoding.
nuclear@2:  *
nuclear@2:  * The savable_state subrecord contains fields that change within an MCU,
nuclear@2:  * but must not be updated permanently until we complete the MCU.
nuclear@2:  */
nuclear@2: 
nuclear@2: typedef struct {
nuclear@2:   unsigned int EOBRUN;			/* remaining EOBs in EOBRUN */
nuclear@2:   int last_dc_val[MAX_COMPS_IN_SCAN];	/* last DC coef for each component */
nuclear@2: } savable_state;
nuclear@2: 
nuclear@2: /* This macro is to work around compilers with missing or broken
nuclear@2:  * structure assignment.  You'll need to fix this code if you have
nuclear@2:  * such a compiler and you change MAX_COMPS_IN_SCAN.
nuclear@2:  */
nuclear@2: 
nuclear@2: #ifndef NO_STRUCT_ASSIGN
nuclear@2: #define ASSIGN_STATE(dest,src)  ((dest) = (src))
nuclear@2: #else
nuclear@2: #if MAX_COMPS_IN_SCAN == 4
nuclear@2: #define ASSIGN_STATE(dest,src)  \
nuclear@2: 	((dest).EOBRUN = (src).EOBRUN, \
nuclear@2: 	 (dest).last_dc_val[0] = (src).last_dc_val[0], \
nuclear@2: 	 (dest).last_dc_val[1] = (src).last_dc_val[1], \
nuclear@2: 	 (dest).last_dc_val[2] = (src).last_dc_val[2], \
nuclear@2: 	 (dest).last_dc_val[3] = (src).last_dc_val[3])
nuclear@2: #endif
nuclear@2: #endif
nuclear@2: 
nuclear@2: 
nuclear@2: typedef struct {
nuclear@2:   struct jpeg_entropy_decoder pub; /* public fields */
nuclear@2: 
nuclear@2:   /* These fields are loaded into local variables at start of each MCU.
nuclear@2:    * In case of suspension, we exit WITHOUT updating them.
nuclear@2:    */
nuclear@2:   bitread_perm_state bitstate;	/* Bit buffer at start of MCU */
nuclear@2:   savable_state saved;		/* Other state at start of MCU */
nuclear@2: 
nuclear@2:   /* These fields are NOT loaded into local working state. */
nuclear@2:   unsigned int restarts_to_go;	/* MCUs left in this restart interval */
nuclear@2: 
nuclear@2:   /* Pointers to derived tables (these workspaces have image lifespan) */
nuclear@2:   d_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
nuclear@2: 
nuclear@2:   d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */
nuclear@2: } phuff_entropy_decoder;
nuclear@2: 
nuclear@2: typedef phuff_entropy_decoder * phuff_entropy_ptr;
nuclear@2: 
nuclear@2: /* Forward declarations */
nuclear@2: METHODDEF(boolean) decode_mcu_DC_first JPP((j_decompress_ptr cinfo,
nuclear@2: 					    JBLOCKROW *MCU_data));
nuclear@2: METHODDEF(boolean) decode_mcu_AC_first JPP((j_decompress_ptr cinfo,
nuclear@2: 					    JBLOCKROW *MCU_data));
nuclear@2: METHODDEF(boolean) decode_mcu_DC_refine JPP((j_decompress_ptr cinfo,
nuclear@2: 					     JBLOCKROW *MCU_data));
nuclear@2: METHODDEF(boolean) decode_mcu_AC_refine JPP((j_decompress_ptr cinfo,
nuclear@2: 					     JBLOCKROW *MCU_data));
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Initialize for a Huffman-compressed scan.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(void)
nuclear@2: start_pass_phuff_decoder (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
nuclear@2:   boolean is_DC_band, bad;
nuclear@2:   int ci, coefi, tbl;
nuclear@2:   int *coef_bit_ptr;
nuclear@2:   jpeg_component_info * compptr;
nuclear@2: 
nuclear@2:   is_DC_band = (cinfo->Ss == 0);
nuclear@2: 
nuclear@2:   /* Validate scan parameters */
nuclear@2:   bad = FALSE;
nuclear@2:   if (is_DC_band) {
nuclear@2:     if (cinfo->Se != 0)
nuclear@2:       bad = TRUE;
nuclear@2:   } else {
nuclear@2:     /* need not check Ss/Se < 0 since they came from unsigned bytes */
nuclear@2:     if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2)
nuclear@2:       bad = TRUE;
nuclear@2:     /* AC scans may have only one component */
nuclear@2:     if (cinfo->comps_in_scan != 1)
nuclear@2:       bad = TRUE;
nuclear@2:   }
nuclear@2:   if (cinfo->Ah != 0) {
nuclear@2:     /* Successive approximation refinement scan: must have Al = Ah-1. */
nuclear@2:     if (cinfo->Al != cinfo->Ah-1)
nuclear@2:       bad = TRUE;
nuclear@2:   }
nuclear@2:   if (cinfo->Al > 13)		/* need not check for < 0 */
nuclear@2:     bad = TRUE;
nuclear@2:   /* Arguably the maximum Al value should be less than 13 for 8-bit precision,
nuclear@2:    * but the spec doesn't say so, and we try to be liberal about what we
nuclear@2:    * accept.  Note: large Al values could result in out-of-range DC
nuclear@2:    * coefficients during early scans, leading to bizarre displays due to
nuclear@2:    * overflows in the IDCT math.  But we won't crash.
nuclear@2:    */
nuclear@2:   if (bad)
nuclear@2:     ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
nuclear@2: 	     cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
nuclear@2:   /* Update progression status, and verify that scan order is legal.
nuclear@2:    * Note that inter-scan inconsistencies are treated as warnings
nuclear@2:    * not fatal errors ... not clear if this is right way to behave.
nuclear@2:    */
nuclear@2:   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
nuclear@2:     int cindex = cinfo->cur_comp_info[ci]->component_index;
nuclear@2:     coef_bit_ptr = & cinfo->coef_bits[cindex][0];
nuclear@2:     if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
nuclear@2:       WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
nuclear@2:     for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
nuclear@2:       int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
nuclear@2:       if (cinfo->Ah != expected)
nuclear@2: 	WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
nuclear@2:       coef_bit_ptr[coefi] = cinfo->Al;
nuclear@2:     }
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Select MCU decoding routine */
nuclear@2:   if (cinfo->Ah == 0) {
nuclear@2:     if (is_DC_band)
nuclear@2:       entropy->pub.decode_mcu = decode_mcu_DC_first;
nuclear@2:     else
nuclear@2:       entropy->pub.decode_mcu = decode_mcu_AC_first;
nuclear@2:   } else {
nuclear@2:     if (is_DC_band)
nuclear@2:       entropy->pub.decode_mcu = decode_mcu_DC_refine;
nuclear@2:     else
nuclear@2:       entropy->pub.decode_mcu = decode_mcu_AC_refine;
nuclear@2:   }
nuclear@2: 
nuclear@2:   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
nuclear@2:     compptr = cinfo->cur_comp_info[ci];
nuclear@2:     /* Make sure requested tables are present, and compute derived tables.
nuclear@2:      * We may build same derived table more than once, but it's not expensive.
nuclear@2:      */
nuclear@2:     if (is_DC_band) {
nuclear@2:       if (cinfo->Ah == 0) {	/* DC refinement needs no table */
nuclear@2: 	tbl = compptr->dc_tbl_no;
nuclear@2: 	jpeg_make_d_derived_tbl(cinfo, TRUE, tbl,
nuclear@2: 				& entropy->derived_tbls[tbl]);
nuclear@2:       }
nuclear@2:     } else {
nuclear@2:       tbl = compptr->ac_tbl_no;
nuclear@2:       jpeg_make_d_derived_tbl(cinfo, FALSE, tbl,
nuclear@2: 			      & entropy->derived_tbls[tbl]);
nuclear@2:       /* remember the single active table */
nuclear@2:       entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
nuclear@2:     }
nuclear@2:     /* Initialize DC predictions to 0 */
nuclear@2:     entropy->saved.last_dc_val[ci] = 0;
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Initialize bitread state variables */
nuclear@2:   entropy->bitstate.bits_left = 0;
nuclear@2:   entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
nuclear@2:   entropy->pub.insufficient_data = FALSE;
nuclear@2: 
nuclear@2:   /* Initialize private state variables */
nuclear@2:   entropy->saved.EOBRUN = 0;
nuclear@2: 
nuclear@2:   /* Initialize restart counter */
nuclear@2:   entropy->restarts_to_go = cinfo->restart_interval;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Figure F.12: extend sign bit.
nuclear@2:  * On some machines, a shift and add will be faster than a table lookup.
nuclear@2:  */
nuclear@2: 
nuclear@2: #ifdef AVOID_TABLES
nuclear@2: 
nuclear@2: #define HUFF_EXTEND(x,s)  ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x))
nuclear@2: 
nuclear@2: #else
nuclear@2: 
nuclear@2: #define HUFF_EXTEND(x,s)  ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))
nuclear@2: 
nuclear@2: static const int extend_test[16] =   /* entry n is 2**(n-1) */
nuclear@2:   { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
nuclear@2:     0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };
nuclear@2: 
nuclear@2: static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */
nuclear@2:   { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
nuclear@2:     ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
nuclear@2:     ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
nuclear@2:     ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 };
nuclear@2: 
nuclear@2: #endif /* AVOID_TABLES */
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Check for a restart marker & resynchronize decoder.
nuclear@2:  * Returns FALSE if must suspend.
nuclear@2:  */
nuclear@2: 
nuclear@2: LOCAL(boolean)
nuclear@2: process_restart (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
nuclear@2:   int ci;
nuclear@2: 
nuclear@2:   /* Throw away any unused bits remaining in bit buffer; */
nuclear@2:   /* include any full bytes in next_marker's count of discarded bytes */
nuclear@2:   cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
nuclear@2:   entropy->bitstate.bits_left = 0;
nuclear@2: 
nuclear@2:   /* Advance past the RSTn marker */
nuclear@2:   if (! (*cinfo->marker->read_restart_marker) (cinfo))
nuclear@2:     return FALSE;
nuclear@2: 
nuclear@2:   /* Re-initialize DC predictions to 0 */
nuclear@2:   for (ci = 0; ci < cinfo->comps_in_scan; ci++)
nuclear@2:     entropy->saved.last_dc_val[ci] = 0;
nuclear@2:   /* Re-init EOB run count, too */
nuclear@2:   entropy->saved.EOBRUN = 0;
nuclear@2: 
nuclear@2:   /* Reset restart counter */
nuclear@2:   entropy->restarts_to_go = cinfo->restart_interval;
nuclear@2: 
nuclear@2:   /* Reset out-of-data flag, unless read_restart_marker left us smack up
nuclear@2:    * against a marker.  In that case we will end up treating the next data
nuclear@2:    * segment as empty, and we can avoid producing bogus output pixels by
nuclear@2:    * leaving the flag set.
nuclear@2:    */
nuclear@2:   if (cinfo->unread_marker == 0)
nuclear@2:     entropy->pub.insufficient_data = FALSE;
nuclear@2: 
nuclear@2:   return TRUE;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Huffman MCU decoding.
nuclear@2:  * Each of these routines decodes and returns one MCU's worth of
nuclear@2:  * Huffman-compressed coefficients. 
nuclear@2:  * The coefficients are reordered from zigzag order into natural array order,
nuclear@2:  * but are not dequantized.
nuclear@2:  *
nuclear@2:  * The i'th block of the MCU is stored into the block pointed to by
nuclear@2:  * MCU_data[i].  WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
nuclear@2:  *
nuclear@2:  * We return FALSE if data source requested suspension.  In that case no
nuclear@2:  * changes have been made to permanent state.  (Exception: some output
nuclear@2:  * coefficients may already have been assigned.  This is harmless for
nuclear@2:  * spectral selection, since we'll just re-assign them on the next call.
nuclear@2:  * Successive approximation AC refinement has to be more careful, however.)
nuclear@2:  */
nuclear@2: 
nuclear@2: /*
nuclear@2:  * MCU decoding for DC initial scan (either spectral selection,
nuclear@2:  * or first pass of successive approximation).
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(boolean)
nuclear@2: decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
nuclear@2: {   
nuclear@2:   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
nuclear@2:   int Al = cinfo->Al;
nuclear@2:   register int s, r;
nuclear@2:   int blkn, ci;
nuclear@2:   JBLOCKROW block;
nuclear@2:   BITREAD_STATE_VARS;
nuclear@2:   savable_state state;
nuclear@2:   d_derived_tbl * tbl;
nuclear@2:   jpeg_component_info * compptr;
nuclear@2: 
nuclear@2:   /* Process restart marker if needed; may have to suspend */
nuclear@2:   if (cinfo->restart_interval) {
nuclear@2:     if (entropy->restarts_to_go == 0)
nuclear@2:       if (! process_restart(cinfo))
nuclear@2: 	return FALSE;
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* If we've run out of data, just leave the MCU set to zeroes.
nuclear@2:    * This way, we return uniform gray for the remainder of the segment.
nuclear@2:    */
nuclear@2:   if (! entropy->pub.insufficient_data) {
nuclear@2: 
nuclear@2:     /* Load up working state */
nuclear@2:     BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
nuclear@2:     ASSIGN_STATE(state, entropy->saved);
nuclear@2: 
nuclear@2:     /* Outer loop handles each block in the MCU */
nuclear@2: 
nuclear@2:     for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
nuclear@2:       block = MCU_data[blkn];
nuclear@2:       ci = cinfo->MCU_membership[blkn];
nuclear@2:       compptr = cinfo->cur_comp_info[ci];
nuclear@2:       tbl = entropy->derived_tbls[compptr->dc_tbl_no];
nuclear@2: 
nuclear@2:       /* Decode a single block's worth of coefficients */
nuclear@2: 
nuclear@2:       /* Section F.2.2.1: decode the DC coefficient difference */
nuclear@2:       HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
nuclear@2:       if (s) {
nuclear@2: 	CHECK_BIT_BUFFER(br_state, s, return FALSE);
nuclear@2: 	r = GET_BITS(s);
nuclear@2: 	s = HUFF_EXTEND(r, s);
nuclear@2:       }
nuclear@2: 
nuclear@2:       /* Convert DC difference to actual value, update last_dc_val */
nuclear@2:       s += state.last_dc_val[ci];
nuclear@2:       state.last_dc_val[ci] = s;
nuclear@2:       /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
nuclear@2:       (*block)[0] = (JCOEF) (s << Al);
nuclear@2:     }
nuclear@2: 
nuclear@2:     /* Completed MCU, so update state */
nuclear@2:     BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
nuclear@2:     ASSIGN_STATE(entropy->saved, state);
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Account for restart interval (no-op if not using restarts) */
nuclear@2:   entropy->restarts_to_go--;
nuclear@2: 
nuclear@2:   return TRUE;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * MCU decoding for AC initial scan (either spectral selection,
nuclear@2:  * or first pass of successive approximation).
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(boolean)
nuclear@2: decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
nuclear@2: {   
nuclear@2:   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
nuclear@2:   int Se = cinfo->Se;
nuclear@2:   int Al = cinfo->Al;
nuclear@2:   register int s, k, r;
nuclear@2:   unsigned int EOBRUN;
nuclear@2:   JBLOCKROW block;
nuclear@2:   BITREAD_STATE_VARS;
nuclear@2:   d_derived_tbl * tbl;
nuclear@2: 
nuclear@2:   /* Process restart marker if needed; may have to suspend */
nuclear@2:   if (cinfo->restart_interval) {
nuclear@2:     if (entropy->restarts_to_go == 0)
nuclear@2:       if (! process_restart(cinfo))
nuclear@2: 	return FALSE;
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* If we've run out of data, just leave the MCU set to zeroes.
nuclear@2:    * This way, we return uniform gray for the remainder of the segment.
nuclear@2:    */
nuclear@2:   if (! entropy->pub.insufficient_data) {
nuclear@2: 
nuclear@2:     /* Load up working state.
nuclear@2:      * We can avoid loading/saving bitread state if in an EOB run.
nuclear@2:      */
nuclear@2:     EOBRUN = entropy->saved.EOBRUN;	/* only part of saved state we need */
nuclear@2: 
nuclear@2:     /* There is always only one block per MCU */
nuclear@2: 
nuclear@2:     if (EOBRUN > 0)		/* if it's a band of zeroes... */
nuclear@2:       EOBRUN--;			/* ...process it now (we do nothing) */
nuclear@2:     else {
nuclear@2:       BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
nuclear@2:       block = MCU_data[0];
nuclear@2:       tbl = entropy->ac_derived_tbl;
nuclear@2: 
nuclear@2:       for (k = cinfo->Ss; k <= Se; k++) {
nuclear@2: 	HUFF_DECODE(s, br_state, tbl, return FALSE, label2);
nuclear@2: 	r = s >> 4;
nuclear@2: 	s &= 15;
nuclear@2: 	if (s) {
nuclear@2: 	  k += r;
nuclear@2: 	  CHECK_BIT_BUFFER(br_state, s, return FALSE);
nuclear@2: 	  r = GET_BITS(s);
nuclear@2: 	  s = HUFF_EXTEND(r, s);
nuclear@2: 	  /* Scale and output coefficient in natural (dezigzagged) order */
nuclear@2: 	  (*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al);
nuclear@2: 	} else {
nuclear@2: 	  if (r == 15) {	/* ZRL */
nuclear@2: 	    k += 15;		/* skip 15 zeroes in band */
nuclear@2: 	  } else {		/* EOBr, run length is 2^r + appended bits */
nuclear@2: 	    EOBRUN = 1 << r;
nuclear@2: 	    if (r) {		/* EOBr, r > 0 */
nuclear@2: 	      CHECK_BIT_BUFFER(br_state, r, return FALSE);
nuclear@2: 	      r = GET_BITS(r);
nuclear@2: 	      EOBRUN += r;
nuclear@2: 	    }
nuclear@2: 	    EOBRUN--;		/* this band is processed at this moment */
nuclear@2: 	    break;		/* force end-of-band */
nuclear@2: 	  }
nuclear@2: 	}
nuclear@2:       }
nuclear@2: 
nuclear@2:       BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
nuclear@2:     }
nuclear@2: 
nuclear@2:     /* Completed MCU, so update state */
nuclear@2:     entropy->saved.EOBRUN = EOBRUN;	/* only part of saved state we need */
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Account for restart interval (no-op if not using restarts) */
nuclear@2:   entropy->restarts_to_go--;
nuclear@2: 
nuclear@2:   return TRUE;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * MCU decoding for DC successive approximation refinement scan.
nuclear@2:  * Note: we assume such scans can be multi-component, although the spec
nuclear@2:  * is not very clear on the point.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(boolean)
nuclear@2: decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
nuclear@2: {   
nuclear@2:   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
nuclear@2:   int p1 = 1 << cinfo->Al;	/* 1 in the bit position being coded */
nuclear@2:   int blkn;
nuclear@2:   JBLOCKROW block;
nuclear@2:   BITREAD_STATE_VARS;
nuclear@2: 
nuclear@2:   /* Process restart marker if needed; may have to suspend */
nuclear@2:   if (cinfo->restart_interval) {
nuclear@2:     if (entropy->restarts_to_go == 0)
nuclear@2:       if (! process_restart(cinfo))
nuclear@2: 	return FALSE;
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Not worth the cycles to check insufficient_data here,
nuclear@2:    * since we will not change the data anyway if we read zeroes.
nuclear@2:    */
nuclear@2: 
nuclear@2:   /* Load up working state */
nuclear@2:   BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
nuclear@2: 
nuclear@2:   /* Outer loop handles each block in the MCU */
nuclear@2: 
nuclear@2:   for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
nuclear@2:     block = MCU_data[blkn];
nuclear@2: 
nuclear@2:     /* Encoded data is simply the next bit of the two's-complement DC value */
nuclear@2:     CHECK_BIT_BUFFER(br_state, 1, return FALSE);
nuclear@2:     if (GET_BITS(1))
nuclear@2:       (*block)[0] |= p1;
nuclear@2:     /* Note: since we use |=, repeating the assignment later is safe */
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Completed MCU, so update state */
nuclear@2:   BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
nuclear@2: 
nuclear@2:   /* Account for restart interval (no-op if not using restarts) */
nuclear@2:   entropy->restarts_to_go--;
nuclear@2: 
nuclear@2:   return TRUE;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * MCU decoding for AC successive approximation refinement scan.
nuclear@2:  */
nuclear@2: 
nuclear@2: METHODDEF(boolean)
nuclear@2: decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
nuclear@2: {   
nuclear@2:   phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
nuclear@2:   int Se = cinfo->Se;
nuclear@2:   int p1 = 1 << cinfo->Al;	/* 1 in the bit position being coded */
nuclear@2:   int m1 = (-1) << cinfo->Al;	/* -1 in the bit position being coded */
nuclear@2:   register int s, k, r;
nuclear@2:   unsigned int EOBRUN;
nuclear@2:   JBLOCKROW block;
nuclear@2:   JCOEFPTR thiscoef;
nuclear@2:   BITREAD_STATE_VARS;
nuclear@2:   d_derived_tbl * tbl;
nuclear@2:   int num_newnz;
nuclear@2:   int newnz_pos[DCTSIZE2];
nuclear@2: 
nuclear@2:   /* Process restart marker if needed; may have to suspend */
nuclear@2:   if (cinfo->restart_interval) {
nuclear@2:     if (entropy->restarts_to_go == 0)
nuclear@2:       if (! process_restart(cinfo))
nuclear@2: 	return FALSE;
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* If we've run out of data, don't modify the MCU.
nuclear@2:    */
nuclear@2:   if (! entropy->pub.insufficient_data) {
nuclear@2: 
nuclear@2:     /* Load up working state */
nuclear@2:     BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
nuclear@2:     EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
nuclear@2: 
nuclear@2:     /* There is always only one block per MCU */
nuclear@2:     block = MCU_data[0];
nuclear@2:     tbl = entropy->ac_derived_tbl;
nuclear@2: 
nuclear@2:     /* If we are forced to suspend, we must undo the assignments to any newly
nuclear@2:      * nonzero coefficients in the block, because otherwise we'd get confused
nuclear@2:      * next time about which coefficients were already nonzero.
nuclear@2:      * But we need not undo addition of bits to already-nonzero coefficients;
nuclear@2:      * instead, we can test the current bit to see if we already did it.
nuclear@2:      */
nuclear@2:     num_newnz = 0;
nuclear@2: 
nuclear@2:     /* initialize coefficient loop counter to start of band */
nuclear@2:     k = cinfo->Ss;
nuclear@2: 
nuclear@2:     if (EOBRUN == 0) {
nuclear@2:       for (; k <= Se; k++) {
nuclear@2: 	HUFF_DECODE(s, br_state, tbl, goto undoit, label3);
nuclear@2: 	r = s >> 4;
nuclear@2: 	s &= 15;
nuclear@2: 	if (s) {
nuclear@2: 	  if (s != 1)		/* size of new coef should always be 1 */
nuclear@2: 	    WARNMS(cinfo, JWRN_HUFF_BAD_CODE);
nuclear@2: 	  CHECK_BIT_BUFFER(br_state, 1, goto undoit);
nuclear@2: 	  if (GET_BITS(1))
nuclear@2: 	    s = p1;		/* newly nonzero coef is positive */
nuclear@2: 	  else
nuclear@2: 	    s = m1;		/* newly nonzero coef is negative */
nuclear@2: 	} else {
nuclear@2: 	  if (r != 15) {
nuclear@2: 	    EOBRUN = 1 << r;	/* EOBr, run length is 2^r + appended bits */
nuclear@2: 	    if (r) {
nuclear@2: 	      CHECK_BIT_BUFFER(br_state, r, goto undoit);
nuclear@2: 	      r = GET_BITS(r);
nuclear@2: 	      EOBRUN += r;
nuclear@2: 	    }
nuclear@2: 	    break;		/* rest of block is handled by EOB logic */
nuclear@2: 	  }
nuclear@2: 	  /* note s = 0 for processing ZRL */
nuclear@2: 	}
nuclear@2: 	/* Advance over already-nonzero coefs and r still-zero coefs,
nuclear@2: 	 * appending correction bits to the nonzeroes.  A correction bit is 1
nuclear@2: 	 * if the absolute value of the coefficient must be increased.
nuclear@2: 	 */
nuclear@2: 	do {
nuclear@2: 	  thiscoef = *block + jpeg_natural_order[k];
nuclear@2: 	  if (*thiscoef != 0) {
nuclear@2: 	    CHECK_BIT_BUFFER(br_state, 1, goto undoit);
nuclear@2: 	    if (GET_BITS(1)) {
nuclear@2: 	      if ((*thiscoef & p1) == 0) { /* do nothing if already set it */
nuclear@2: 		if (*thiscoef >= 0)
nuclear@2: 		  *thiscoef += p1;
nuclear@2: 		else
nuclear@2: 		  *thiscoef += m1;
nuclear@2: 	      }
nuclear@2: 	    }
nuclear@2: 	  } else {
nuclear@2: 	    if (--r < 0)
nuclear@2: 	      break;		/* reached target zero coefficient */
nuclear@2: 	  }
nuclear@2: 	  k++;
nuclear@2: 	} while (k <= Se);
nuclear@2: 	if (s) {
nuclear@2: 	  int pos = jpeg_natural_order[k];
nuclear@2: 	  /* Output newly nonzero coefficient */
nuclear@2: 	  (*block)[pos] = (JCOEF) s;
nuclear@2: 	  /* Remember its position in case we have to suspend */
nuclear@2: 	  newnz_pos[num_newnz++] = pos;
nuclear@2: 	}
nuclear@2:       }
nuclear@2:     }
nuclear@2: 
nuclear@2:     if (EOBRUN > 0) {
nuclear@2:       /* Scan any remaining coefficient positions after the end-of-band
nuclear@2:        * (the last newly nonzero coefficient, if any).  Append a correction
nuclear@2:        * bit to each already-nonzero coefficient.  A correction bit is 1
nuclear@2:        * if the absolute value of the coefficient must be increased.
nuclear@2:        */
nuclear@2:       for (; k <= Se; k++) {
nuclear@2: 	thiscoef = *block + jpeg_natural_order[k];
nuclear@2: 	if (*thiscoef != 0) {
nuclear@2: 	  CHECK_BIT_BUFFER(br_state, 1, goto undoit);
nuclear@2: 	  if (GET_BITS(1)) {
nuclear@2: 	    if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */
nuclear@2: 	      if (*thiscoef >= 0)
nuclear@2: 		*thiscoef += p1;
nuclear@2: 	      else
nuclear@2: 		*thiscoef += m1;
nuclear@2: 	    }
nuclear@2: 	  }
nuclear@2: 	}
nuclear@2:       }
nuclear@2:       /* Count one block completed in EOB run */
nuclear@2:       EOBRUN--;
nuclear@2:     }
nuclear@2: 
nuclear@2:     /* Completed MCU, so update state */
nuclear@2:     BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
nuclear@2:     entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Account for restart interval (no-op if not using restarts) */
nuclear@2:   entropy->restarts_to_go--;
nuclear@2: 
nuclear@2:   return TRUE;
nuclear@2: 
nuclear@2: undoit:
nuclear@2:   /* Re-zero any output coefficients that we made newly nonzero */
nuclear@2:   while (num_newnz > 0)
nuclear@2:     (*block)[newnz_pos[--num_newnz]] = 0;
nuclear@2: 
nuclear@2:   return FALSE;
nuclear@2: }
nuclear@2: 
nuclear@2: 
nuclear@2: /*
nuclear@2:  * Module initialization routine for progressive Huffman entropy decoding.
nuclear@2:  */
nuclear@2: 
nuclear@2: GLOBAL(void)
nuclear@2: jinit_phuff_decoder (j_decompress_ptr cinfo)
nuclear@2: {
nuclear@2:   phuff_entropy_ptr entropy;
nuclear@2:   int *coef_bit_ptr;
nuclear@2:   int ci, i;
nuclear@2: 
nuclear@2:   entropy = (phuff_entropy_ptr)
nuclear@2:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@2: 				SIZEOF(phuff_entropy_decoder));
nuclear@2:   cinfo->entropy = (struct jpeg_entropy_decoder *) entropy;
nuclear@2:   entropy->pub.start_pass = start_pass_phuff_decoder;
nuclear@2: 
nuclear@2:   /* Mark derived tables unallocated */
nuclear@2:   for (i = 0; i < NUM_HUFF_TBLS; i++) {
nuclear@2:     entropy->derived_tbls[i] = NULL;
nuclear@2:   }
nuclear@2: 
nuclear@2:   /* Create progression status table */
nuclear@2:   cinfo->coef_bits = (int (*)[DCTSIZE2])
nuclear@2:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@2: 				cinfo->num_components*DCTSIZE2*SIZEOF(int));
nuclear@2:   coef_bit_ptr = & cinfo->coef_bits[0][0];
nuclear@2:   for (ci = 0; ci < cinfo->num_components; ci++) 
nuclear@2:     for (i = 0; i < DCTSIZE2; i++)
nuclear@2:       *coef_bit_ptr++ = -1;
nuclear@2: }
nuclear@2: 
nuclear@2: #endif /* D_PROGRESSIVE_SUPPORTED */