00518 {
00519   huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
00520   int blkn;
00521   BITREAD_STATE_VARS;
00522   savable_state state;
00523 
00524   /* Process restart marker if needed; may have to suspend */
00525   if (cinfo->restart_interval) {
00526     if (entropy->restarts_to_go == 0)
00527       if (! process_restart(cinfo))
00528         return FALSE;
00529   }
00530 
00531   /* If we've run out of data, just leave the MCU set to zeroes.
00532    * This way, we return uniform gray for the remainder of the segment.
00533    */
00534   if (! entropy->pub.insufficient_data) {
00535 
00536     /* Load up working state */
00537     BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
00538     ASSIGN_STATE(state, entropy->saved);
00539 
00540     /* Outer loop handles each block in the MCU */
00541 
00542     for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
00543       JBLOCKROW block = MCU_data[blkn];
00544       d_derived_tbl * dctbl = entropy->dc_cur_tbls[blkn];
00545       d_derived_tbl * actbl = entropy->ac_cur_tbls[blkn];
00546       register int s, k, r;
00547 
00548       /* Decode a single block's worth of coefficients */
00549 
00550       /* Section F.2.2.1: decode the DC coefficient difference */
00551       HUFF_DECODE(s, br_state, dctbl, return FALSE, label1);
00552       if (s) {
00553         CHECK_BIT_BUFFER(br_state, s, return FALSE);
00554         r = GET_BITS(s);
00555         s = HUFF_EXTEND(r, s);
00556       }
00557 
00558       if (entropy->dc_needed[blkn]) {
00559         /* Convert DC difference to actual value, update last_dc_val */
00560         int ci = cinfo->MCU_membership[blkn];
00561         s += state.last_dc_val[ci];
00562         state.last_dc_val[ci] = s;
00563         /* Output the DC coefficient (assumes jpeg_natural_order[0] = 0) */
00564         (*block)[0] = (JCOEF) s;
00565       }
00566 
00567       if (entropy->ac_needed[blkn]) {
00568 
00569         /* Section F.2.2.2: decode the AC coefficients */
00570         /* Since zeroes are skipped, output area must be cleared beforehand */
00571         for (k = 1; k < DCTSIZE2; k++) {
00572           HUFF_DECODE(s, br_state, actbl, return FALSE, label2);
00573       
00574           r = s >> 4;
00575           s &= 15;
00576       
00577           if (s) {
00578             k += r;
00579             CHECK_BIT_BUFFER(br_state, s, return FALSE);
00580             r = GET_BITS(s);
00581             s = HUFF_EXTEND(r, s);
00582             /* Output coefficient in natural (dezigzagged) order.
00583              * Note: the extra entries in jpeg_natural_order[] will save us
00584              * if k >= DCTSIZE2, which could happen if the data is corrupted.
00585              */
00586             (*block)[jpeg_natural_order[k]] = (JCOEF) s;
00587           } else {
00588             if (r != 15)
00589               break;
00590             k += 15;
00591           }
00592         }
00593 
00594       } else {
00595 
00596         /* Section F.2.2.2: decode the AC coefficients */
00597         /* In this path we just discard the values */
00598         for (k = 1; k < DCTSIZE2; k++) {
00599           HUFF_DECODE(s, br_state, actbl, return FALSE, label3);
00600       
00601           r = s >> 4;
00602           s &= 15;
00603       
00604           if (s) {
00605             k += r;
00606             CHECK_BIT_BUFFER(br_state, s, return FALSE);
00607             DROP_BITS(s);
00608           } else {
00609             if (r != 15)
00610               break;
00611             k += 15;
00612           }
00613         }
00614 
00615       }
00616     }
00617 
00618     /* Completed MCU, so update state */
00619     BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
00620     ASSIGN_STATE(entropy->saved, state);
00621   }
00622 
00623   /* Account for restart interval (no-op if not using restarts) */
00624   entropy->restarts_to_go--;
00625 
00626   return TRUE;
00627 }

00636 {
00637   huff_entropy_ptr entropy;
00638   int i;
00639 
00640   entropy = (huff_entropy_ptr)
00641     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
00642                                 SIZEOF(huff_entropy_decoder));
00643   cinfo->entropy = (struct jpeg_entropy_decoder *) entropy;
00644   entropy->pub.start_pass = start_pass_huff_decoder;
00645   entropy->pub.decode_mcu = decode_mcu;
00646 
00647   /* Mark tables unallocated */
00648   for (i = 0; i < NUM_HUFF_TBLS; i++) {
00649     entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;
00650   }
00651 }

00296 {
00297   /* Copy heavily used state fields into locals (hopefully registers) */
00298   register const JOCTET * next_input_byte = state->next_input_byte;
00299   register size_t bytes_in_buffer = state->bytes_in_buffer;
00300   j_decompress_ptr cinfo = state->cinfo;
00301 
00302   /* Attempt to load at least MIN_GET_BITS bits into get_buffer. */
00303   /* (It is assumed that no request will be for more than that many bits.) */
00304   /* We fail to do so only if we hit a marker or are forced to suspend. */
00305 
00306   if (cinfo->unread_marker == 0) {      /* cannot advance past a marker */
00307     while (bits_left < MIN_GET_BITS) {
00308       register int c;
00309 
00310       /* Attempt to read a byte */
00311       if (bytes_in_buffer == 0) {
00312         if (! (*cinfo->src->fill_input_buffer) (cinfo))
00313           return FALSE;
00314         next_input_byte = cinfo->src->next_input_byte;
00315         bytes_in_buffer = cinfo->src->bytes_in_buffer;
00316       }
00317       bytes_in_buffer--;
00318       c = GETJOCTET(*next_input_byte++);
00319 
00320       /* If it's 0xFF, check and discard stuffed zero byte */
00321       if (c == 0xFF) {
00322         /* Loop here to discard any padding FF's on terminating marker,
00323          * so that we can save a valid unread_marker value.  NOTE: we will
00324          * accept multiple FF's followed by a 0 as meaning a single FF data
00325          * byte.  This data pattern is not valid according to the standard.
00326          */
00327         do {
00328           if (bytes_in_buffer == 0) {
00329             if (! (*cinfo->src->fill_input_buffer) (cinfo))
00330               return FALSE;
00331             next_input_byte = cinfo->src->next_input_byte;
00332             bytes_in_buffer = cinfo->src->bytes_in_buffer;
00333           }
00334           bytes_in_buffer--;
00335           c = GETJOCTET(*next_input_byte++);
00336         } while (c == 0xFF);
00337 
00338         if (c == 0) {
00339           /* Found FF/00, which represents an FF data byte */
00340           c = 0xFF;
00341         } else {
00342           /* Oops, it's actually a marker indicating end of compressed data.
00343            * Save the marker code for later use.
00344            * Fine point: it might appear that we should save the marker into
00345            * bitread working state, not straight into permanent state.  But
00346            * once we have hit a marker, we cannot need to suspend within the
00347            * current MCU, because we will read no more bytes from the data
00348            * source.  So it is OK to update permanent state right away.
00349            */
00350           cinfo->unread_marker = c;
00351           /* See if we need to insert some fake zero bits. */
00352           goto no_more_bytes;
00353         }
00354       }
00355 
00356       /* OK, load c into get_buffer */
00357       get_buffer = (get_buffer << 8) | c;
00358       bits_left += 8;
00359     } /* end while */
00360   } else {
00361   no_more_bytes:
00362     /* We get here if we've read the marker that terminates the compressed
00363      * data segment.  There should be enough bits in the buffer register
00364      * to satisfy the request; if so, no problem.
00365      */
00366     if (nbits > bits_left) {
00367       /* Uh-oh.  Report corrupted data to user and stuff zeroes into
00368        * the data stream, so that we can produce some kind of image.
00369        * We use a nonvolatile flag to ensure that only one warning message
00370        * appears per data segment.
00371        */
00372       if (! cinfo->entropy->insufficient_data) {
00373         WARNMS(cinfo, JWRN_HIT_MARKER);
00374         cinfo->entropy->insufficient_data = TRUE;
00375       }
00376       /* Fill the buffer with zero bits */
00377       get_buffer <<= MIN_GET_BITS - bits_left;
00378       bits_left = MIN_GET_BITS;
00379     }
00380   }
00381 
00382   /* Unload the local registers */
00383   state->next_input_byte = next_input_byte;
00384   state->bytes_in_buffer = bytes_in_buffer;
00385   state->get_buffer = get_buffer;
00386   state->bits_left = bits_left;
00387 
00388   return TRUE;
00389 }

00401 {
00402   register int l = min_bits;
00403   register INT32 code;
00404 
00405   /* HUFF_DECODE has determined that the code is at least min_bits */
00406   /* bits long, so fetch that many bits in one swoop. */
00407 
00408   CHECK_BIT_BUFFER(*state, l, return -1);
00409   code = GET_BITS(l);
00410 
00411   /* Collect the rest of the Huffman code one bit at a time. */
00412   /* This is per Figure F.16 in the JPEG spec. */
00413 
00414   while (code > htbl->maxcode[l]) {
00415     code <<= 1;
00416     CHECK_BIT_BUFFER(*state, 1, return -1);
00417     code |= GET_BITS(1);
00418     l++;
00419   }
00420 
00421   /* Unload the local registers */
00422   state->get_buffer = get_buffer;
00423   state->bits_left = bits_left;
00424 
00425   /* With garbage input we may reach the sentinel value l = 17. */
00426 
00427   if (l > 16) {
00428     WARNMS(state->cinfo, JWRN_HUFF_BAD_CODE);
00429     return 0;                   /* fake a zero as the safest result */
00430   }
00431 
00432   return htbl->pub->huffval[ (int) (code + htbl->valoffset[l]) ];
00433 }

00151 {
00152   JHUFF_TBL *htbl;
00153   d_derived_tbl *dtbl;
00154   int p, i, l, si, numsymbols;
00155   int lookbits, ctr;
00156   char huffsize[257];
00157   unsigned int huffcode[257];
00158   unsigned int code;
00159 
00160   /* Note that huffsize[] and huffcode[] are filled in code-length order,
00161    * paralleling the order of the symbols themselves in htbl->huffval[].
00162    */
00163 
00164   /* Find the input Huffman table */
00165   if (tblno < 0 || tblno >= NUM_HUFF_TBLS)
00166     ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
00167   htbl =
00168     isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno];
00169   if (htbl == NULL)
00170     ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
00171 
00172   /* Allocate a workspace if we haven't already done so. */
00173   if (*pdtbl == NULL)
00174     *pdtbl = (d_derived_tbl *)
00175       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
00176                                   SIZEOF(d_derived_tbl));
00177   dtbl = *pdtbl;
00178   dtbl->pub = htbl;             /* fill in back link */
00179   
00180   /* Figure C.1: make table of Huffman code length for each symbol */
00181 
00182   p = 0;
00183   for (l = 1; l <= 16; l++) {
00184     i = (int) htbl->bits[l];
00185     if (i < 0 || p + i > 256)   /* protect against table overrun */
00186       ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
00187     while (i--)
00188       huffsize[p++] = (char) l;
00189   }
00190   huffsize[p] = 0;
00191   numsymbols = p;
00192   
00193   /* Figure C.2: generate the codes themselves */
00194   /* We also validate that the counts represent a legal Huffman code tree. */
00195   
00196   code = 0;
00197   si = huffsize[0];
00198   p = 0;
00199   while (huffsize[p]) {
00200     while (((int) huffsize[p]) == si) {
00201       huffcode[p++] = code;
00202       code++;
00203     }
00204     /* code is now 1 more than the last code used for codelength si; but
00205      * it must still fit in si bits, since no code is allowed to be all ones.
00206      */
00207     if (((INT32) code) >= (((INT32) 1) << si))
00208       ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
00209     code <<= 1;
00210     si++;
00211   }
00212 
00213   /* Figure F.15: generate decoding tables for bit-sequential decoding */
00214 
00215   p = 0;
00216   for (l = 1; l <= 16; l++) {
00217     if (htbl->bits[l]) {
00218       /* valoffset[l] = huffval[] index of 1st symbol of code length l,
00219        * minus the minimum code of length l
00220        */
00221       dtbl->valoffset[l] = (INT32) p - (INT32) huffcode[p];
00222       p += htbl->bits[l];
00223       dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */
00224     } else {
00225       dtbl->maxcode[l] = -1;    /* -1 if no codes of this length */
00226     }
00227   }
00228   dtbl->maxcode[17] = 0xFFFFFL; /* ensures jpeg_huff_decode terminates */
00229 
00230   /* Compute lookahead tables to speed up decoding.
00231    * First we set all the table entries to 0, indicating "too long";
00232    * then we iterate through the Huffman codes that are short enough and
00233    * fill in all the entries that correspond to bit sequences starting
00234    * with that code.
00235    */
00236 
00237   MEMZERO(dtbl->look_nbits, SIZEOF(dtbl->look_nbits));
00238 
00239   p = 0;
00240   for (l = 1; l <= HUFF_LOOKAHEAD; l++) {
00241     for (i = 1; i <= (int) htbl->bits[l]; i++, p++) {
00242       /* l = current code's length, p = its index in huffcode[] & huffval[]. */
00243       /* Generate left-justified code followed by all possible bit sequences */
00244       lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l);
00245       for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--) {
00246         dtbl->look_nbits[lookbits] = l;
00247         dtbl->look_sym[lookbits] = htbl->huffval[p];
00248         lookbits++;
00249       }
00250     }
00251   }
00252 
00253   /* Validate symbols as being reasonable.
00254    * For AC tables, we make no check, but accept all byte values 0..255.
00255    * For DC tables, we require the symbols to be in range 0..15.
00256    * (Tighter bounds could be applied depending on the data depth and mode,
00257    * but this is sufficient to ensure safe decoding.)
00258    */
00259   if (isDC) {
00260     for (i = 0; i < numsymbols; i++) {
00261       int sym = htbl->huffval[i];
00262       if (sym < 0 || sym > 15)
00263         ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
00264     }
00265   }
00266 }

00469 {
00470   huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
00471   int ci;
00472 
00473   /* Throw away any unused bits remaining in bit buffer; */
00474   /* include any full bytes in next_marker's count of discarded bytes */
00475   cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
00476   entropy->bitstate.bits_left = 0;
00477 
00478   /* Advance past the RSTn marker */
00479   if (! (*cinfo->marker->read_restart_marker) (cinfo))
00480     return FALSE;
00481 
00482   /* Re-initialize DC predictions to 0 */
00483   for (ci = 0; ci < cinfo->comps_in_scan; ci++)
00484     entropy->saved.last_dc_val[ci] = 0;
00485 
00486   /* Reset restart counter */
00487   entropy->restarts_to_go = cinfo->restart_interval;
00488 
00489   /* Reset out-of-data flag, unless read_restart_marker left us smack up
00490    * against a marker.  In that case we will end up treating the next data
00491    * segment as empty, and we can avoid producing bogus output pixels by
00492    * leaving the flag set.
00493    */
00494   if (cinfo->unread_marker == 0)
00495     entropy->pub.insufficient_data = FALSE;
00496 
00497   return TRUE;
00498 }

00087 {
00088   huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
00089   int ci, blkn, dctbl, actbl;
00090   jpeg_component_info * compptr;
00091 
00092   /* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG.
00093    * This ought to be an error condition, but we make it a warning because
00094    * there are some baseline files out there with all zeroes in these bytes.
00095    */
00096   if (cinfo->Ss != 0 || cinfo->Se != DCTSIZE2-1 ||
00097       cinfo->Ah != 0 || cinfo->Al != 0)
00098     WARNMS(cinfo, JWRN_NOT_SEQUENTIAL);
00099 
00100   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
00101     compptr = cinfo->cur_comp_info[ci];
00102     dctbl = compptr->dc_tbl_no;
00103     actbl = compptr->ac_tbl_no;
00104     /* Compute derived values for Huffman tables */
00105     /* We may do this more than once for a table, but it's not expensive */
00106     jpeg_make_d_derived_tbl(cinfo, TRUE, dctbl,
00107                             & entropy->dc_derived_tbls[dctbl]);
00108     jpeg_make_d_derived_tbl(cinfo, FALSE, actbl,
00109                             & entropy->ac_derived_tbls[actbl]);
00110     /* Initialize DC predictions to 0 */
00111     entropy->saved.last_dc_val[ci] = 0;
00112   }
00113 
00114   /* Precalculate decoding info for each block in an MCU of this scan */
00115   for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
00116     ci = cinfo->MCU_membership[blkn];
00117     compptr = cinfo->cur_comp_info[ci];
00118     /* Precalculate which table to use for each block */
00119     entropy->dc_cur_tbls[blkn] = entropy->dc_derived_tbls[compptr->dc_tbl_no];
00120     entropy->ac_cur_tbls[blkn] = entropy->ac_derived_tbls[compptr->ac_tbl_no];
00121     /* Decide whether we really care about the coefficient values */
00122     if (compptr->component_needed) {
00123       entropy->dc_needed[blkn] = TRUE;
00124       /* we don't need the ACs if producing a 1/8th-size image */
00125       entropy->ac_needed[blkn] = (compptr->DCT_scaled_size > 1);
00126     } else {
00127       entropy->dc_needed[blkn] = entropy->ac_needed[blkn] = FALSE;
00128     }
00129   }
00130 
00131   /* Initialize bitread state variables */
00132   entropy->bitstate.bits_left = 0;
00133   entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
00134   entropy->pub.insufficient_data = FALSE;
00135 
00136   /* Initialize restart counter */
00137   entropy->restarts_to_go = cinfo->restart_interval;
00138 }

 
  { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
    ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
    ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
    ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 }

   
  { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
    0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 }