diff --git a/jdhuff.c b/jdhuff.c
index 3ac46cf..e92ad9a 100644
--- a/jdhuff.c
+++ b/jdhuff.c
@@ -1,35 +1,172 @@
 /*
  * jdhuff.c
  *
- * Copyright (C) 1991, 1992, 1993, Thomas G. Lane.
+ * Copyright (C) 1991-1994, Thomas G. Lane.
  * This file is part of the Independent JPEG Group's software.
  * For conditions of distribution and use, see the accompanying README file.
  *
  * This file contains Huffman entropy decoding routines.
- * These routines are invoked via the methods entropy_decode
- * and entropy_decode_init/term.
+ *
+ * Much of the complexity here has to do with supporting input suspension.
+ * If the data source module demands suspension, we want to be able to back
+ * up to the start of the current MCU.  To do this, we copy state variables
+ * into local working storage, and update them back to the permanent JPEG
+ * objects only upon successful completion of an MCU.
  */
 
+#define JPEG_INTERNALS
 #include "jinclude.h"
+#include "jpeglib.h"
 
 
-/* Static variables to avoid passing 'round extra parameters */
+/* Derived data constructed for each Huffman table */
 
-static decompress_info_ptr dcinfo;
+#define HUFF_LOOKAHEAD	8	/* # of bits of lookahead */
 
-static INT32 get_buffer;	/* current bit-extraction buffer */
-static int bits_left;		/* # of unused bits in it */
-static boolean printed_eod;	/* flag to suppress multiple end-of-data msgs */
+typedef struct {
+  /* Basic tables: (element [0] of each array is unused) */
+  INT32 mincode[17];		/* smallest code of length k */
+  INT32 maxcode[18];		/* largest code of length k (-1 if none) */
+  /* (maxcode[17] is a sentinel to ensure huff_DECODE terminates) */
+  int valptr[17];		/* huffval[] index of 1st symbol of length k */
+
+  /* Back link to public Huffman table (needed only in slow_DECODE) */
+  JHUFF_TBL *pub;
+
+  /* Lookahead tables: indexed by the next HUFF_LOOKAHEAD bits of
+   * the input data stream.  If the next Huffman code is no more
+   * than HUFF_LOOKAHEAD bits long, we can obtain its length and
+   * the corresponding symbol directly from these tables.
+   */
+  int look_nbits[1<<HUFF_LOOKAHEAD]; /* # bits, or 0 if too long */
+  UINT8 look_sym[1<<HUFF_LOOKAHEAD]; /* symbol, or unused */
+} D_DERIVED_TBL;
+
+/* Expanded entropy decoder object for Huffman decoding.
+ *
+ * The savable_state subrecord contains fields that change within an MCU,
+ * but must not be updated permanently until we complete the MCU.
+ */
+
+typedef struct {
+  INT32 get_buffer;		/* current bit-extraction buffer */
+  int bits_left;		/* # of unused bits in it */
+  int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
+} savable_state;
+
+/* This macro is to work around compilers with missing or broken
+ * structure assignment.  You'll need to fix this code if you have
+ * such a compiler and you change MAX_COMPS_IN_SCAN.
+ */
+
+#ifndef NO_STRUCT_ASSIGN
+#define ASSIGN_STATE(dest,src)  ((dest) = (src))
+#else
+#if MAX_COMPS_IN_SCAN == 4
+#define ASSIGN_STATE(dest,src)  \
+	((dest).get_buffer = (src).get_buffer, \
+	 (dest).bits_left = (src).bits_left, \
+	 (dest).last_dc_val[0] = (src).last_dc_val[0], \
+	 (dest).last_dc_val[1] = (src).last_dc_val[1], \
+	 (dest).last_dc_val[2] = (src).last_dc_val[2], \
+	 (dest).last_dc_val[3] = (src).last_dc_val[3])
+#endif
+#endif
+
+
+typedef struct {
+  struct jpeg_entropy_decoder pub; /* public fields */
+
+  savable_state saved;		/* Bit buffer & DC state at start of MCU */
+
+  /* These fields are NOT loaded into local working state. */
+  unsigned int restarts_to_go;	/* MCUs left in this restart interval */
+  boolean printed_eod;		/* flag to suppress extra end-of-data msgs */
+
+  /* Pointers to derived tables (these workspaces have image lifespan) */
+  D_DERIVED_TBL * dc_derived_tbls[NUM_HUFF_TBLS];
+  D_DERIVED_TBL * ac_derived_tbls[NUM_HUFF_TBLS];
+} huff_entropy_decoder;
+
+typedef huff_entropy_decoder * huff_entropy_ptr;
+
+/* Working state while scanning an MCU.
+ * This struct contains all the fields that are needed by subroutines.
+ */
+
+typedef struct {
+  int unread_marker;		/* nonzero if we have hit a marker */
+  const JOCTET * next_input_byte; /* => next byte to read from source */
+  size_t bytes_in_buffer;	/* # of bytes remaining in source buffer */
+  savable_state cur;		/* Current bit buffer & DC state */
+  j_decompress_ptr cinfo;	/* fill_bit_buffer needs access to this */
+} working_state;
+
+
+/* Forward declarations */
+LOCAL void fix_huff_tbl JPP((j_decompress_ptr cinfo, JHUFF_TBL * htbl,
+			     D_DERIVED_TBL ** pdtbl));
+
+
+/*
+ * Initialize for a Huffman-compressed scan.
+ */
+
+METHODDEF void
+start_pass_huff_decoder (j_decompress_ptr cinfo)
+{
+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
+  int ci, dctbl, actbl;
+  jpeg_component_info * compptr;
+
+  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
+    compptr = cinfo->cur_comp_info[ci];
+    dctbl = compptr->dc_tbl_no;
+    actbl = compptr->ac_tbl_no;
+    /* Make sure requested tables are present */
+    if (dctbl < 0 || dctbl >= NUM_HUFF_TBLS ||
+	cinfo->dc_huff_tbl_ptrs[dctbl] == NULL)
+      ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, dctbl);
+    if (actbl < 0 || actbl >= NUM_HUFF_TBLS ||
+	cinfo->ac_huff_tbl_ptrs[actbl] == NULL)
+      ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, actbl);
+    /* Compute derived values for Huffman tables */
+    /* We may do this more than once for a table, but it's not expensive */
+    fix_huff_tbl(cinfo, cinfo->dc_huff_tbl_ptrs[dctbl],
+		 & entropy->dc_derived_tbls[dctbl]);
+    fix_huff_tbl(cinfo, cinfo->ac_huff_tbl_ptrs[actbl],
+		 & entropy->ac_derived_tbls[actbl]);
+    /* Initialize DC predictions to 0 */
+    entropy->saved.last_dc_val[ci] = 0;
+  }
+
+  /* Initialize private state variables */
+  entropy->saved.bits_left = 0;
+  entropy->printed_eod = FALSE;
+
+  /* Initialize restart counter */
+  entropy->restarts_to_go = cinfo->restart_interval;
+}
+
 
 LOCAL void
-fix_huff_tbl (HUFF_TBL * htbl)
-/* Compute derived values for a Huffman table */
+fix_huff_tbl (j_decompress_ptr cinfo, JHUFF_TBL * htbl, D_DERIVED_TBL ** pdtbl)
+/* Compute the derived values for a Huffman table */
 {
+  D_DERIVED_TBL *dtbl;
   int p, i, l, si;
   int lookbits, ctr;
   char huffsize[257];
-  UINT16 huffcode[257];
-  UINT16 code;
+  unsigned int huffcode[257];
+  unsigned int code;
+
+  /* Allocate a workspace if we haven't already done so. */
+  if (*pdtbl == NULL)
+    *pdtbl = (D_DERIVED_TBL *)
+      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+				  SIZEOF(D_DERIVED_TBL));
+  dtbl = *pdtbl;
+  dtbl->pub = htbl;		/* fill in back link */
   
   /* Figure C.1: make table of Huffman code length for each symbol */
   /* Note that this is in code-length order. */
@@ -61,15 +198,15 @@
   p = 0;
   for (l = 1; l <= 16; l++) {
     if (htbl->bits[l]) {
-      htbl->priv.dec.valptr[l] = p; /* huffval[] index of 1st symbol of code length l */
-      htbl->priv.dec.mincode[l] = huffcode[p]; /* minimum code of length l */
+      dtbl->valptr[l] = p; /* huffval[] index of 1st symbol of code length l */
+      dtbl->mincode[l] = huffcode[p]; /* minimum code of length l */
       p += htbl->bits[l];
-      htbl->priv.dec.maxcode[l] = huffcode[p-1]; /* maximum code of length l */
+      dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */
     } else {
-      htbl->priv.dec.maxcode[l] = -1; /* -1 if no codes of this length */
+      dtbl->maxcode[l] = -1;	/* -1 if no codes of this length */
     }
   }
-  htbl->priv.dec.maxcode[17] = 0xFFFFFL; /* ensures huff_DECODE terminates */
+  dtbl->maxcode[17] = 0xFFFFFL; /* ensures huff_DECODE terminates */
 
   /* Compute lookahead tables to speed up decoding.
    * First we set all the table entries to 0, indicating "too long";
@@ -78,7 +215,7 @@
    * with that code.
    */
 
-  MEMZERO(htbl->priv.dec.look_nbits, SIZEOF(htbl->priv.dec.look_nbits));
+  MEMZERO(dtbl->look_nbits, SIZEOF(dtbl->look_nbits));
 
   p = 0;
   for (l = 1; l <= HUFF_LOOKAHEAD; l++) {
@@ -87,8 +224,8 @@
       /* Generate left-justified code followed by all possible bit sequences */
       lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l);
       for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--) {
-	htbl->priv.dec.look_nbits[lookbits] = l;
-	htbl->priv.dec.look_sym[lookbits] = htbl->huffval[p];
+	dtbl->look_nbits[lookbits] = l;
+	dtbl->look_sym[lookbits] = htbl->huffval[p];
 	lookbits++;
       }
     }
@@ -107,13 +244,15 @@
  * bits, fill_bit_buffer is called; it will attempt to fill get_buffer to
  * the "high water mark" (not just to the number of bits needed; this reduces
  * the function-call overhead cost of entering fill_bit_buffer).
- * On return, fill_bit_buffer guarantees that get_buffer contains at least
- * the requested number of bits --- dummy zeroes are inserted if necessary.
+ * Note that fill_bit_buffer may return FALSE to indicate suspension.
+ * On TRUE return, fill_bit_buffer guarantees that get_buffer contains
+ * at least the requested number of bits --- dummy zeroes are inserted if
+ * necessary.
  *
  * On most machines MIN_GET_BITS should be 25 to allow the full 32-bit width
  * of get_buffer to be used.  (On machines with wider words, an even larger
  * buffer could be used.)  However, on some machines 32-bit shifts are
- * relatively slow and take time proportional to the number of places shifted.
+ * quite slow and take time proportional to the number of places shifted.
  * (This is true with most PC compilers, for instance.)  In this case it may
  * be a win to set MIN_GET_BITS to the minimum value of 15.  This reduces the
  * average shift distance at the cost of more calls to fill_bit_buffer.
@@ -126,37 +265,70 @@
 #endif
 
 
-LOCAL void
-fill_bit_buffer (int nbits)
+LOCAL boolean
+fill_bit_buffer (working_state * state, int nbits)
 /* Load up the bit buffer to a depth of at least nbits */
 {
+  /* Copy heavily used state fields into locals (hopefully registers) */
+  register const JOCTET * next_input_byte = state->next_input_byte;
+  register size_t bytes_in_buffer = state->bytes_in_buffer;
+  register INT32 get_buffer = state->cur.get_buffer;
+  register int bits_left = state->cur.bits_left;
+  register int c;
+
   /* Attempt to load at least MIN_GET_BITS bits into get_buffer. */
   /* (It is assumed that no request will be for more than that many bits.) */
+
   while (bits_left < MIN_GET_BITS) {
-    register int c = JGETC(dcinfo);
-    
+    /* Attempt to read a byte */
+    if (state->unread_marker != 0)
+      goto no_more_data;	/* can't advance past a marker */
+
+    if (bytes_in_buffer == 0) {
+      if (! (*state->cinfo->src->fill_input_buffer) (state->cinfo))
+	return FALSE;
+      next_input_byte = state->cinfo->src->next_input_byte;
+      bytes_in_buffer = state->cinfo->src->bytes_in_buffer;
+    }
+    bytes_in_buffer--;
+    c = GETJOCTET(*next_input_byte++);
+
     /* If it's 0xFF, check and discard stuffed zero byte */
     if (c == 0xFF) {
-      int c2 = JGETC(dcinfo);
-      if (c2 != 0) {
+      do {
+	if (bytes_in_buffer == 0) {
+	  if (! (*state->cinfo->src->fill_input_buffer) (state->cinfo))
+	    return FALSE;
+	  next_input_byte = state->cinfo->src->next_input_byte;
+	  bytes_in_buffer = state->cinfo->src->bytes_in_buffer;
+	}
+	bytes_in_buffer--;
+	c = GETJOCTET(*next_input_byte++);
+      } while (c == 0xFF);
+
+      if (c == 0) {
+	/* Found FF/00, which represents an FF data byte */
+	c = 0xFF;
+      } else {
 	/* Oops, it's actually a marker indicating end of compressed data. */
 	/* Better put it back for use later */
-	JUNGETC(c2,dcinfo);
-	JUNGETC(c,dcinfo);
+	state->unread_marker = c;
+
+      no_more_data:
 	/* There should be enough bits still left in the data segment; */
-	/* if so, just break out of the while loop. */
+	/* if so, just break out of the outer while loop. */
 	if (bits_left >= nbits)
 	  break;
 	/* Uh-oh.  Report corrupted data to user and stuff zeroes into
 	 * the data stream, so that we can produce some kind of image.
 	 * Note that this will be repeated for each byte demanded for the
-	 * rest of the segment; this is a bit slow but not unreasonably so.
+	 * rest of the segment; this is slow but not unreasonably so.
 	 * The main thing is to avoid getting a zillion warnings, hence
 	 * we use a flag to ensure that only one warning appears.
 	 */
-	if (! printed_eod) {
-	  WARNMS(dcinfo->emethods, "Corrupt JPEG data: premature end of data segment");
-	  printed_eod = TRUE;
+	if (! ((huff_entropy_ptr) state->cinfo->entropy)->printed_eod) {
+	  WARNMS(state->cinfo, JWRN_HIT_MARKER);
+	  ((huff_entropy_ptr) state->cinfo->entropy)->printed_eod = TRUE;
 	}
 	c = 0;			/* insert a zero byte into bit buffer */
       }
@@ -166,31 +338,50 @@
     get_buffer = (get_buffer << 8) | c;
     bits_left += 8;
   }
+
+  /* Unload the local registers */
+  state->next_input_byte = next_input_byte;
+  state->bytes_in_buffer = bytes_in_buffer;
+  state->cur.get_buffer = get_buffer;
+  state->cur.bits_left = bits_left;
+
+  return TRUE;
 }
 
 
 /*
  * These macros provide the in-line portion of bit fetching.
- * Correct usage is:
- *	check_bit_buffer(n);		ensure there are N bits in get_buffer
- *      val = get_bits(n);		fetch N bits
- * The value n should be a simple variable, not an expression, because it
+ * Use check_bit_buffer to ensure there are N bits in get_buffer
+ * before using get_bits, peek_bits, or drop_bits.
+ *	check_bit_buffer(state,n,action);
+ *		Ensure there are N bits in get_buffer; if suspend, take action.
+ *      val = get_bits(state,n);
+ *		Fetch next N bits.
+ *      val = peek_bits(state,n);
+ *		Fetch next N bits without removing them from the buffer.
+ *	drop_bits(state,n);
+ *		Discard next N bits.
+ * The value N should be a simple variable, not an expression, because it
  * is evaluated multiple times.
- * peek_bits() fetches next N bits without removing them from the buffer.
  */
 
-#define check_bit_buffer(nbits) \
-	{ if (bits_left < (nbits))  fill_bit_buffer(nbits); }
+#define check_bit_buffer(state,nbits,action) \
+	{ if ((state).cur.bits_left < (nbits))  \
+	    if (! fill_bit_buffer(&(state), nbits))  \
+	      { action; } }
 
-#define get_bits(nbits) \
-	(((int) (get_buffer >> (bits_left -= (nbits)))) & ((1<<(nbits))-1))
+#define get_bits(state,nbits) \
+	(((int) ((state).cur.get_buffer >> ((state).cur.bits_left -= (nbits)))) & ((1<<(nbits))-1))
 
-#define peek_bits(nbits) \
-	(((int) (get_buffer >> (bits_left -  (nbits)))) & ((1<<(nbits))-1))
+#define peek_bits(state,nbits) \
+	(((int) ((state).cur.get_buffer >> ((state).cur.bits_left -  (nbits)))) & ((1<<(nbits))-1))
+
+#define drop_bits(state,nbits) \
+	((state).cur.bits_left -= (nbits))
 
 
 /*
- * Routines to extract next Huffman-coded symbol from input bit stream.
+ * Code for extracting next Huffman-coded symbol from input bit stream.
  * We use a lookahead table to process codes of up to HUFF_LOOKAHEAD bits
  * without looping.  Usually, more than 95% of the Huffman codes will be 8
  * or fewer bits long.  The few overlength codes are handled with a loop.
@@ -198,32 +389,37 @@
  * routine slow_DECODE is rarely entered and need not be inline code.
  *
  * Notes about the huff_DECODE macro:
- * 1. The first if-test is coded to call fill_bit_buffer only when necessary.
- * 2. If the lookahead succeeds, we need only decrement bits_left to remove
- *    the proper number of bits from get_buffer.
- * 3. If the lookahead table contains no entry, the next code must be
- *    more than HUFF_LOOKAHEAD bits long.
- * 4. Near the end of the data segment, we may fail to get enough bits
+ * 1. Near the end of the data segment, we may fail to get enough bits
  *    for a lookahead.  In that case, we do it the hard way.
+ * 2. If the lookahead table contains no entry, the next code must be
+ *    more than HUFF_LOOKAHEAD bits long.
+ * 3. slow_DECODE returns -1 if forced to suspend.
  */
 
-#define huff_DECODE(htbl,result) \
-{ register int nb, look;					\
-  if (bits_left >= HUFF_LOOKAHEAD ||				\
-      (fill_bit_buffer(0), bits_left >= HUFF_LOOKAHEAD)) {	\
-    look = peek_bits(HUFF_LOOKAHEAD);				\
-    if ((nb = htbl->priv.dec.look_nbits[look]) != 0) {		\
-      bits_left -= nb;						\
-      result = htbl->priv.dec.look_sym[look];			\
-    } else							\
-      result = slow_DECODE(htbl, HUFF_LOOKAHEAD+1);		\
-  } else							\
-    result = slow_DECODE(htbl, 1);				\
+#define huff_DECODE(result,state,htbl,donelabel) \
+{ if (state.cur.bits_left < HUFF_LOOKAHEAD) {  \
+    if (! fill_bit_buffer(&state, 0)) return FALSE;  \
+    if (state.cur.bits_left < HUFF_LOOKAHEAD) {  \
+      if ((result = slow_DECODE(&state, htbl, 1)) < 0) return FALSE;  \
+      goto donelabel;  \
+    }  \
+  }  \
+  { register int nb, look;  \
+    look = peek_bits(state, HUFF_LOOKAHEAD);  \
+    if ((nb = htbl->look_nbits[look]) != 0) {  \
+      drop_bits(state, nb);  \
+      result = htbl->look_sym[look];  \
+    } else {  \
+      if ((result = slow_DECODE(&state, htbl, HUFF_LOOKAHEAD+1)) < 0)  \
+	return FALSE;  \
+    }  \
+  }  \
+donelabel:;  \
 }
 
   
 LOCAL int
-slow_DECODE (HUFF_TBL * htbl, int min_bits)
+slow_DECODE (working_state * state, D_DERIVED_TBL * htbl, int min_bits)
 {
   register int l = min_bits;
   register INT32 code;
@@ -231,28 +427,28 @@
   /* huff_DECODE has determined that the code is at least min_bits */
   /* bits long, so fetch that many bits in one swoop. */
 
-  check_bit_buffer(l);
-  code = get_bits(l);
+  check_bit_buffer(*state, l, return -1);
+  code = get_bits(*state, l);
 
   /* Collect the rest of the Huffman code one bit at a time. */
   /* This is per Figure F.16 in the JPEG spec. */
 
-  while (code > htbl->priv.dec.maxcode[l]) {
+  while (code > htbl->maxcode[l]) {
     code <<= 1;
-    check_bit_buffer(1);
-    code |= get_bits(1);
+    check_bit_buffer(*state, 1, return -1);
+    code |= get_bits(*state, 1);
     l++;
   }
 
   /* With garbage input we may reach the sentinel value l = 17. */
 
   if (l > 16) {
-    WARNMS(dcinfo->emethods, "Corrupt JPEG data: bad Huffman code");
+    WARNMS(state->cinfo, JWRN_HUFF_BAD_CODE);
     return 0;			/* fake a zero as the safest result */
   }
 
-  return htbl->huffval[ htbl->priv.dec.valptr[l] +
-		        ((int) (code - htbl->priv.dec.mincode[l])) ];
+  return htbl->pub->huffval[ htbl->valptr[l] +
+			    ((int) (code - htbl->mincode[l])) ];
 }
 
 
@@ -282,87 +478,35 @@
 
 
 /*
- * Initialize for a Huffman-compressed scan.
- * This is invoked after reading the SOS marker.
- */
-
-METHODDEF void
-decoder_init (decompress_info_ptr cinfo)
-{
-  short ci;
-  jpeg_component_info * compptr;
-
-  /* Initialize static variables */
-  dcinfo = cinfo;
-  bits_left = 0;
-  printed_eod = FALSE;
-
-  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
-    compptr = cinfo->cur_comp_info[ci];
-    /* Make sure requested tables are present */
-    if (cinfo->dc_huff_tbl_ptrs[compptr->dc_tbl_no] == NULL ||
-	cinfo->ac_huff_tbl_ptrs[compptr->ac_tbl_no] == NULL)
-      ERREXIT(cinfo->emethods, "Use of undefined Huffman table");
-    /* Compute derived values for Huffman tables */
-    /* We may do this more than once for same table, but it's not a big deal */
-    fix_huff_tbl(cinfo->dc_huff_tbl_ptrs[compptr->dc_tbl_no]);
-    fix_huff_tbl(cinfo->ac_huff_tbl_ptrs[compptr->ac_tbl_no]);
-    /* Initialize DC predictions to 0 */
-    cinfo->last_dc_val[ci] = 0;
-  }
-
-  /* Initialize restart stuff */
-  cinfo->restarts_to_go = cinfo->restart_interval;
-  cinfo->next_restart_num = 0;
-}
-
-
-/*
  * Check for a restart marker & resynchronize decoder.
+ * Returns FALSE if must suspend.
  */
 
-LOCAL void
-process_restart (decompress_info_ptr cinfo)
+LOCAL boolean
+process_restart (j_decompress_ptr cinfo)
 {
-  int c, nbytes;
-  short ci;
+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
+  int ci;
 
-  /* Throw away any unused bits remaining in bit buffer */
-  nbytes = bits_left / 8;	/* count any full bytes loaded into buffer */
-  bits_left = 0;
-  printed_eod = FALSE;		/* next segment can get another warning */
+  /* Throw away any unused bits remaining in bit buffer; */
+  /* include any full bytes in next_marker's count of discarded bytes */
+  cinfo->marker->discarded_bytes += entropy->saved.bits_left / 8;
+  entropy->saved.bits_left = 0;
 
-  /* Scan for next JPEG marker */
-  do {
-    do {			/* skip any non-FF bytes */
-      nbytes++;
-      c = JGETC(cinfo);
-    } while (c != 0xFF);
-    do {			/* skip any duplicate FFs */
-      /* we don't increment nbytes here since extra FFs are legal */
-      c = JGETC(cinfo);
-    } while (c == 0xFF);
-  } while (c == 0);		/* repeat if it was a stuffed FF/00 */
-
-  if (nbytes != 1)
-    WARNMS2(cinfo->emethods,
-	    "Corrupt JPEG data: %d extraneous bytes before marker 0x%02x",
-	    nbytes-1, c);
-
-  if (c != (RST0 + cinfo->next_restart_num)) {
-    /* Uh-oh, the restart markers have been messed up too. */
-    /* Let the file-format module try to figure out how to resync. */
-    (*cinfo->methods->resync_to_restart) (cinfo, c);
-  } else
-    TRACEMS1(cinfo->emethods, 2, "RST%d", cinfo->next_restart_num);
+  /* Advance past the RSTn marker */
+  if (! (*cinfo->marker->read_restart_marker) (cinfo))
+    return FALSE;
 
   /* Re-initialize DC predictions to 0 */
   for (ci = 0; ci < cinfo->comps_in_scan; ci++)
-    cinfo->last_dc_val[ci] = 0;
+    entropy->saved.last_dc_val[ci] = 0;
 
-  /* Update restart state */
-  cinfo->restarts_to_go = cinfo->restart_interval;
-  cinfo->next_restart_num = (cinfo->next_restart_num + 1) & 7;
+  /* Reset restart counter */
+  entropy->restarts_to_go = cinfo->restart_interval;
+
+  entropy->printed_eod = FALSE; /* next segment can get another warning */
+
+  return TRUE;
 }
 
 
@@ -372,7 +516,7 @@
  * we put some extra zeroes after the real entries.
  */
 
-static const short ZAG[DCTSIZE2+16] = {
+static const int ZAG[DCTSIZE2+16] = {
   0,  1,  8, 16,  9,  2,  3, 10,
  17, 24, 32, 25, 18, 11,  4,  5,
  12, 19, 26, 33, 40, 48, 41, 34,
@@ -388,104 +532,156 @@
 
 /*
  * Decode and return one MCU's worth of Huffman-compressed coefficients.
- * This routine also handles quantization descaling and zigzag reordering
- * of coefficient values.
+ * The coefficients are reordered from zigzag order into natural array order,
+ * but are not dequantized.
  *
  * The i'th block of the MCU is stored into the block pointed to by
  * MCU_data[i].  WE ASSUME THIS AREA HAS BEEN ZEROED BY THE CALLER.
  * (Wholesale zeroing is usually a little faster than retail...)
+ *
+ * Returns FALSE if data source requested suspension.  In that case no
+ * changes have been made to permanent state.  (Exception: some output
+ * coefficients may already have been assigned.  This is harmless for
+ * this module, but would not work for decoding progressive JPEG.)
  */
 
-METHODDEF void
-decode_mcu (decompress_info_ptr cinfo, JBLOCKROW *MCU_data)
+METHODDEF boolean
+decode_mcu (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
 {
+  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
   register int s, k, r;
-  short blkn, ci;
-  register JBLOCKROW block;
-  register QUANT_TBL_PTR quanttbl;
-  HUFF_TBL *dctbl;
-  HUFF_TBL *actbl;
+  int blkn, ci;
+  JBLOCKROW block;
+  working_state state;
+  D_DERIVED_TBL * dctbl;
+  D_DERIVED_TBL * actbl;
   jpeg_component_info * compptr;
 
-  /* Account for restart interval, process restart marker if needed */
+  /* Process restart marker if needed; may have to suspend */
   if (cinfo->restart_interval) {
-    if (cinfo->restarts_to_go == 0)
-      process_restart(cinfo);
-    cinfo->restarts_to_go--;
+    if (entropy->restarts_to_go == 0)
+      if (! process_restart(cinfo))
+	return FALSE;
   }
 
+  /* Load up working state */
+  state.unread_marker = cinfo->unread_marker;
+  state.next_input_byte = cinfo->src->next_input_byte;
+  state.bytes_in_buffer = cinfo->src->bytes_in_buffer;
+  ASSIGN_STATE(state.cur, entropy->saved);
+  state.cinfo = cinfo;
+
   /* Outer loop handles each block in the MCU */
 
   for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
     block = MCU_data[blkn];
     ci = cinfo->MCU_membership[blkn];
     compptr = cinfo->cur_comp_info[ci];
-    quanttbl = cinfo->quant_tbl_ptrs[compptr->quant_tbl_no];
-    actbl = cinfo->ac_huff_tbl_ptrs[compptr->ac_tbl_no];
-    dctbl = cinfo->dc_huff_tbl_ptrs[compptr->dc_tbl_no];
+    dctbl = entropy->dc_derived_tbls[compptr->dc_tbl_no];
+    actbl = entropy->ac_derived_tbls[compptr->ac_tbl_no];
 
     /* Decode a single block's worth of coefficients */
 
     /* Section F.2.2.1: decode the DC coefficient difference */
-    huff_DECODE(dctbl, s);
+    huff_DECODE(s, state, dctbl, label1);
     if (s) {
-      check_bit_buffer(s);
-      r = get_bits(s);
+      check_bit_buffer(state, s, return FALSE);
+      r = get_bits(state, s);
       s = huff_EXTEND(r, s);
     }
 
+    /* Shortcut if component's values are not interesting */
+    if (! compptr->component_needed)
+      goto skip_ACs;
+
     /* Convert DC difference to actual value, update last_dc_val */
-    s += cinfo->last_dc_val[ci];
-    cinfo->last_dc_val[ci] = (JCOEF) s;
-    /* Descale and output the DC coefficient (assumes ZAG[0] = 0) */
-    (*block)[0] = (JCOEF) (((JCOEF) s) * quanttbl[0]);
-    
-    /* Section F.2.2.2: decode the AC coefficients */
-    /* Since zero values are skipped, output area must be zeroed beforehand */
-    for (k = 1; k < DCTSIZE2; k++) {
-      huff_DECODE(actbl, s);
+    s += state.cur.last_dc_val[ci];
+    state.cur.last_dc_val[ci] = s;
+    /* Output the DC coefficient (assumes ZAG[0] = 0) */
+    (*block)[0] = (JCOEF) s;
+
+    /* Do we need to decode the AC coefficients for this component? */
+    if (compptr->DCT_scaled_size > 1) {
+
+      /* Section F.2.2.2: decode the AC coefficients */
+      /* Since zeroes are skipped, output area must be cleared beforehand */
+      for (k = 1; k < DCTSIZE2; k++) {
+	huff_DECODE(s, state, actbl, label2);
       
-      r = s >> 4;
-      s &= 15;
+	r = s >> 4;
+	s &= 15;
       
-      if (s) {
-	k += r;
-	check_bit_buffer(s);
-	r = get_bits(s);
-	s = huff_EXTEND(r, s);
-	/* Descale coefficient and output in natural (dezigzagged) order */
-	(*block)[ZAG[k]] = (JCOEF) (((JCOEF) s) * quanttbl[k]);
-      } else {
-	if (r != 15)
-	  break;
-	k += 15;
+	if (s) {
+	  k += r;
+	  check_bit_buffer(state, s, return FALSE);
+	  r = get_bits(state, s);
+	  s = huff_EXTEND(r, s);
+	  /* Output coefficient in natural (dezigzagged) order */
+	  (*block)[ZAG[k]] = (JCOEF) s;
+	} else {
+	  if (r != 15)
+	    break;
+	  k += 15;
+	}
       }
+
+    } else {
+skip_ACs:
+
+      /* Section F.2.2.2: decode the AC coefficients */
+      /* In this path we just discard the values */
+      for (k = 1; k < DCTSIZE2; k++) {
+	huff_DECODE(s, state, actbl, label3);
+      
+	r = s >> 4;
+	s &= 15;
+      
+	if (s) {
+	  k += r;
+	  check_bit_buffer(state, s, return FALSE);
+	  drop_bits(state, s);
+	} else {
+	  if (r != 15)
+	    break;
+	  k += 15;
+	}
+      }
+
     }
   }
+
+  /* Completed MCU, so update state */
+  cinfo->unread_marker = state.unread_marker;
+  cinfo->src->next_input_byte = state.next_input_byte;
+  cinfo->src->bytes_in_buffer = state.bytes_in_buffer;
+  ASSIGN_STATE(entropy->saved, state.cur);
+
+  /* Account for restart interval (no-op if not using restarts) */
+  entropy->restarts_to_go--;
+
+  return TRUE;
 }
 
 
 /*
- * Finish up at the end of a Huffman-compressed scan.
- */
-
-METHODDEF void
-decoder_term (decompress_info_ptr cinfo)
-{
-  /* No work needed */
-}
-
-
-/*
- * The method selection routine for Huffman entropy decoding.
+ * Module initialization routine for Huffman entropy decoding.
  */
 
 GLOBAL void
-jseldhuffman (decompress_info_ptr cinfo)
+jinit_huff_decoder (j_decompress_ptr cinfo)
 {
-  if (! cinfo->arith_code) {
-    cinfo->methods->entropy_decode_init = decoder_init;
-    cinfo->methods->entropy_decode = decode_mcu;
-    cinfo->methods->entropy_decode_term = decoder_term;
+  huff_entropy_ptr entropy;
+  int i;
+
+  entropy = (huff_entropy_ptr)
+    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+				SIZEOF(huff_entropy_decoder));
+  cinfo->entropy = (struct jpeg_entropy_decoder *) entropy;
+  entropy->pub.start_pass = start_pass_huff_decoder;
+  entropy->pub.decode_mcu = decode_mcu;
+
+  /* Mark tables unallocated */
+  for (i = 0; i < NUM_HUFF_TBLS; i++) {
+    entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;
   }
 }