Issue #1933 - Part 2: Update libjpeg-turbo source.

1 files changed, 345 insertions, 160 deletions

diff --git a/media/libjpeg/jdcoefct.c b/media/libjpeg/jdcoefct.c
index 1a48969b83..15e6cded62 100644
--- a/media/libjpeg/jdcoefct.c
+++ b/media/libjpeg/jdcoefct.c
@@ -5,8 +5,8 @@
  * Copyright (C) 1994-1997, Thomas G. Lane.
  * libjpeg-turbo Modifications:
  * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
- * Copyright (C) 2010, 2015-2016, D. R. Commander.
- * Copyright (C) 2015, Google, Inc.
+ * Copyright (C) 2010, 2015-2016, 2019-2020, D. R. Commander.
+ * Copyright (C) 2015, 2020, Google, Inc.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
  *
@@ -25,16 +25,15 @@
 
 
 /* Forward declarations */
-METHODDEF(int) decompress_onepass
-        (j_decompress_ptr cinfo, JSAMPIMAGE output_buf);
+METHODDEF(int) decompress_onepass(j_decompress_ptr cinfo,
+                                  JSAMPIMAGE output_buf);
 #ifdef D_MULTISCAN_FILES_SUPPORTED
-METHODDEF(int) decompress_data
-        (j_decompress_ptr cinfo, JSAMPIMAGE output_buf);
+METHODDEF(int) decompress_data(j_decompress_ptr cinfo, JSAMPIMAGE output_buf);
 #endif
 #ifdef BLOCK_SMOOTHING_SUPPORTED
-LOCAL(boolean) smoothing_ok (j_decompress_ptr cinfo);
-METHODDEF(int) decompress_smooth_data
-        (j_decompress_ptr cinfo, JSAMPIMAGE output_buf);
+LOCAL(boolean) smoothing_ok(j_decompress_ptr cinfo);
+METHODDEF(int) decompress_smooth_data(j_decompress_ptr cinfo,
+                                      JSAMPIMAGE output_buf);
 #endif
 
 
@@ -43,7 +42,7 @@ METHODDEF(int) decompress_smooth_data
  */
 
 METHODDEF(void)
-start_input_pass (j_decompress_ptr cinfo)
+start_input_pass(j_decompress_ptr cinfo)
 {
   cinfo->input_iMCU_row = 0;
   start_iMCU_row(cinfo);
@@ -55,10 +54,10 @@ start_input_pass (j_decompress_ptr cinfo)
  */
 
 METHODDEF(void)
-start_output_pass (j_decompress_ptr cinfo)
+start_output_pass(j_decompress_ptr cinfo)
 {
 #ifdef BLOCK_SMOOTHING_SUPPORTED
-  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
+  my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
 
   /* If multipass, check to see whether to use block smoothing on this pass */
   if (coef->pub.coef_arrays != NULL) {
@@ -83,9 +82,9 @@ start_output_pass (j_decompress_ptr cinfo)
  */
 
 METHODDEF(int)
-decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
+decompress_onepass(j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 {
-  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
+  my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
   JDIMENSION MCU_col_num;       /* index of current MCU within row */
   JDIMENSION last_MCU_col = cinfo->MCUs_per_row - 1;
   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
@@ -101,9 +100,11 @@ decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
     for (MCU_col_num = coef->MCU_ctr; MCU_col_num <= last_MCU_col;
          MCU_col_num++) {
       /* Try to fetch an MCU.  Entropy decoder expects buffer to be zeroed. */
-      jzero_far((void *) coef->MCU_buffer[0],
-                (size_t) (cinfo->blocks_in_MCU * sizeof(JBLOCK)));
-      if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
+      jzero_far((void *)coef->MCU_buffer[0],
+                (size_t)(cinfo->blocks_in_MCU * sizeof(JBLOCK)));
+      if (!cinfo->entropy->insufficient_data)
+        cinfo->master->last_good_iMCU_row = cinfo->input_iMCU_row;
+      if (!(*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
         /* Suspension forced; update state counters and exit */
         coef->MCU_vert_offset = yoffset;
         coef->MCU_ctr = MCU_col_num;
@@ -120,28 +121,28 @@ decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
          * incremented past them!).  Note the inner loop relies on having
          * allocated the MCU_buffer[] blocks sequentially.
          */
-        blkn = 0;                 /* index of current DCT block within MCU */
+        blkn = 0;               /* index of current DCT block within MCU */
         for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
           compptr = cinfo->cur_comp_info[ci];
           /* Don't bother to IDCT an uninteresting component. */
-          if (! compptr->component_needed) {
+          if (!compptr->component_needed) {
             blkn += compptr->MCU_blocks;
             continue;
           }
           inverse_DCT = cinfo->idct->inverse_DCT[compptr->component_index];
-          useful_width = (MCU_col_num < last_MCU_col) ? compptr->MCU_width
-                                                      : compptr->last_col_width;
+          useful_width = (MCU_col_num < last_MCU_col) ?
+                         compptr->MCU_width : compptr->last_col_width;
           output_ptr = output_buf[compptr->component_index] +
-            yoffset * compptr->_DCT_scaled_size;
+                       yoffset * compptr->_DCT_scaled_size;
           start_col = (MCU_col_num - cinfo->master->first_iMCU_col) *
-              compptr->MCU_sample_width;
+                      compptr->MCU_sample_width;
           for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
             if (cinfo->input_iMCU_row < last_iMCU_row ||
-                yoffset+yindex < compptr->last_row_height) {
+                yoffset + yindex < compptr->last_row_height) {
               output_col = start_col;
               for (xindex = 0; xindex < useful_width; xindex++) {
                 (*inverse_DCT) (cinfo, compptr,
-                                (JCOEFPTR) coef->MCU_buffer[blkn+xindex],
+                                (JCOEFPTR)coef->MCU_buffer[blkn + xindex],
                                 output_ptr, output_col);
                 output_col += compptr->_DCT_scaled_size;
               }
@@ -172,7 +173,7 @@ decompress_onepass (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
  */
 
 METHODDEF(int)
-dummy_consume_data (j_decompress_ptr cinfo)
+dummy_consume_data(j_decompress_ptr cinfo)
 {
   return JPEG_SUSPENDED;        /* Always indicate nothing was done */
 }
@@ -188,9 +189,9 @@ dummy_consume_data (j_decompress_ptr cinfo)
  */
 
 METHODDEF(int)
-consume_data (j_decompress_ptr cinfo)
+consume_data(j_decompress_ptr cinfo)
 {
-  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
+  my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
   JDIMENSION MCU_col_num;       /* index of current MCU within row */
   int blkn, ci, xindex, yindex, yoffset;
   JDIMENSION start_col;
@@ -202,9 +203,9 @@ consume_data (j_decompress_ptr cinfo)
   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
     compptr = cinfo->cur_comp_info[ci];
     buffer[ci] = (*cinfo->mem->access_virt_barray)
-      ((j_common_ptr) cinfo, coef->whole_image[compptr->component_index],
+      ((j_common_ptr)cinfo, coef->whole_image[compptr->component_index],
        cinfo->input_iMCU_row * compptr->v_samp_factor,
-       (JDIMENSION) compptr->v_samp_factor, TRUE);
+       (JDIMENSION)compptr->v_samp_factor, TRUE);
     /* Note: entropy decoder expects buffer to be zeroed,
      * but this is handled automatically by the memory manager
      * because we requested a pre-zeroed array.
@@ -222,14 +223,16 @@ consume_data (j_decompress_ptr cinfo)
         compptr = cinfo->cur_comp_info[ci];
         start_col = MCU_col_num * compptr->MCU_width;
         for (yindex = 0; yindex < compptr->MCU_height; yindex++) {
-          buffer_ptr = buffer[ci][yindex+yoffset] + start_col;
+          buffer_ptr = buffer[ci][yindex + yoffset] + start_col;
           for (xindex = 0; xindex < compptr->MCU_width; xindex++) {
             coef->MCU_buffer[blkn++] = buffer_ptr++;
           }
         }
       }
+      if (!cinfo->entropy->insufficient_data)
+        cinfo->master->last_good_iMCU_row = cinfo->input_iMCU_row;
       /* Try to fetch the MCU. */
-      if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
+      if (!(*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
         /* Suspension forced; update state counters and exit */
         coef->MCU_vert_offset = yoffset;
         coef->MCU_ctr = MCU_col_num;
@@ -259,9 +262,9 @@ consume_data (j_decompress_ptr cinfo)
  */
 
 METHODDEF(int)
-decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
+decompress_data(j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 {
-  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
+  my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
   JDIMENSION block_num;
   int ci, block_row, block_rows;
@@ -276,7 +279,7 @@ decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
   while (cinfo->input_scan_number < cinfo->output_scan_number ||
          (cinfo->input_scan_number == cinfo->output_scan_number &&
           cinfo->input_iMCU_row <= cinfo->output_iMCU_row)) {
-    if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
+    if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
       return JPEG_SUSPENDED;
   }
 
@@ -284,19 +287,19 @@ decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     /* Don't bother to IDCT an uninteresting component. */
-    if (! compptr->component_needed)
+    if (!compptr->component_needed)
       continue;
     /* Align the virtual buffer for this component. */
     buffer = (*cinfo->mem->access_virt_barray)
-      ((j_common_ptr) cinfo, coef->whole_image[ci],
+      ((j_common_ptr)cinfo, coef->whole_image[ci],
        cinfo->output_iMCU_row * compptr->v_samp_factor,
-       (JDIMENSION) compptr->v_samp_factor, FALSE);
+       (JDIMENSION)compptr->v_samp_factor, FALSE);
     /* Count non-dummy DCT block rows in this iMCU row. */
     if (cinfo->output_iMCU_row < last_iMCU_row)
       block_rows = compptr->v_samp_factor;
     else {
       /* NB: can't use last_row_height here; it is input-side-dependent! */
-      block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
+      block_rows = (int)(compptr->height_in_blocks % compptr->v_samp_factor);
       if (block_rows == 0) block_rows = compptr->v_samp_factor;
     }
     inverse_DCT = cinfo->idct->inverse_DCT[ci];
@@ -307,8 +310,8 @@ decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
       output_col = 0;
       for (block_num = cinfo->master->first_MCU_col[ci];
            block_num <= cinfo->master->last_MCU_col[ci]; block_num++) {
-        (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) buffer_ptr,
-                        output_ptr, output_col);
+        (*inverse_DCT) (cinfo, compptr, (JCOEFPTR)buffer_ptr, output_ptr,
+                        output_col);
         buffer_ptr++;
         output_col += compptr->_DCT_scaled_size;
       }
@@ -327,19 +330,22 @@ decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 #ifdef BLOCK_SMOOTHING_SUPPORTED
 
 /*
- * This code applies interblock smoothing as described by section K.8
- * of the JPEG standard: the first 5 AC coefficients are estimated from
- * the DC values of a DCT block and its 8 neighboring blocks.
+ * This code applies interblock smoothing; the first 9 AC coefficients are
+ * estimated from the DC values of a DCT block and its 24 neighboring blocks.
  * We apply smoothing only for progressive JPEG decoding, and only if
  * the coefficients it can estimate are not yet known to full precision.
  */
 
-/* Natural-order array positions of the first 5 zigzag-order coefficients */
+/* Natural-order array positions of the first 9 zigzag-order coefficients */
 #define Q01_POS  1
 #define Q10_POS  8
 #define Q20_POS  16
 #define Q11_POS  9
 #define Q02_POS  2
+#define Q03_POS  3
+#define Q12_POS  10
+#define Q21_POS  17
+#define Q30_POS  24
 
 /*
  * Determine whether block smoothing is applicable and safe.
@@ -350,51 +356,64 @@ decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
  */
 
 LOCAL(boolean)
-smoothing_ok (j_decompress_ptr cinfo)
+smoothing_ok(j_decompress_ptr cinfo)
 {
-  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
+  my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
   boolean smoothing_useful = FALSE;
   int ci, coefi;
   jpeg_component_info *compptr;
   JQUANT_TBL *qtable;
-  int *coef_bits;
-  int *coef_bits_latch;
+  int *coef_bits, *prev_coef_bits;
+  int *coef_bits_latch, *prev_coef_bits_latch;
 
-  if (! cinfo->progressive_mode || cinfo->coef_bits == NULL)
+  if (!cinfo->progressive_mode || cinfo->coef_bits == NULL)
     return FALSE;
 
   /* Allocate latch area if not already done */
   if (coef->coef_bits_latch == NULL)
     coef->coef_bits_latch = (int *)
-      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
-                                  cinfo->num_components *
+      (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
+                                  cinfo->num_components * 2 *
                                   (SAVED_COEFS * sizeof(int)));
   coef_bits_latch = coef->coef_bits_latch;
+  prev_coef_bits_latch =
+    &coef->coef_bits_latch[cinfo->num_components * SAVED_COEFS];
 
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     /* All components' quantization values must already be latched. */
     if ((qtable = compptr->quant_table) == NULL)
       return FALSE;
-    /* Verify DC & first 5 AC quantizers are nonzero to avoid zero-divide. */
+    /* Verify DC & first 9 AC quantizers are nonzero to avoid zero-divide. */
     if (qtable->quantval[0] == 0 ||
         qtable->quantval[Q01_POS] == 0 ||
         qtable->quantval[Q10_POS] == 0 ||
         qtable->quantval[Q20_POS] == 0 ||
         qtable->quantval[Q11_POS] == 0 ||
-        qtable->quantval[Q02_POS] == 0)
+        qtable->quantval[Q02_POS] == 0 ||
+        qtable->quantval[Q03_POS] == 0 ||
+        qtable->quantval[Q12_POS] == 0 ||
+        qtable->quantval[Q21_POS] == 0 ||
+        qtable->quantval[Q30_POS] == 0)
       return FALSE;
     /* DC values must be at least partly known for all components. */
     coef_bits = cinfo->coef_bits[ci];
+    prev_coef_bits = cinfo->coef_bits[ci + cinfo->num_components];
     if (coef_bits[0] < 0)
       return FALSE;
+    coef_bits_latch[0] = coef_bits[0];
     /* Block smoothing is helpful if some AC coefficients remain inaccurate. */
-    for (coefi = 1; coefi <= 5; coefi++) {
+    for (coefi = 1; coefi < SAVED_COEFS; coefi++) {
+      if (cinfo->input_scan_number > 1)
+        prev_coef_bits_latch[coefi] = prev_coef_bits[coefi];
+      else
+        prev_coef_bits_latch[coefi] = -1;
       coef_bits_latch[coefi] = coef_bits[coefi];
       if (coef_bits[coefi] != 0)
         smoothing_useful = TRUE;
     }
     coef_bits_latch += SAVED_COEFS;
+    prev_coef_bits_latch += SAVED_COEFS;
   }
 
   return smoothing_useful;
@@ -406,24 +425,27 @@ smoothing_ok (j_decompress_ptr cinfo)
  */
 
 METHODDEF(int)
-decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
+decompress_smooth_data(j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 {
-  my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
+  my_coef_ptr coef = (my_coef_ptr)cinfo->coef;
   JDIMENSION last_iMCU_row = cinfo->total_iMCU_rows - 1;
   JDIMENSION block_num, last_block_column;
   int ci, block_row, block_rows, access_rows;
   JBLOCKARRAY buffer;
-  JBLOCKROW buffer_ptr, prev_block_row, next_block_row;
+  JBLOCKROW buffer_ptr, prev_prev_block_row, prev_block_row;
+  JBLOCKROW next_block_row, next_next_block_row;
   JSAMPARRAY output_ptr;
   JDIMENSION output_col;
   jpeg_component_info *compptr;
   inverse_DCT_method_ptr inverse_DCT;
-  boolean first_row, last_row;
+  boolean change_dc;
   JCOEF *workspace;
   int *coef_bits;
   JQUANT_TBL *quanttbl;
-  JLONG Q00,Q01,Q02,Q10,Q11,Q20, num;
-  int DC1,DC2,DC3,DC4,DC5,DC6,DC7,DC8,DC9;
+  JLONG Q00, Q01, Q02, Q03 = 0, Q10, Q11, Q12 = 0, Q20, Q21 = 0, Q30 = 0, num;
+  int DC01, DC02, DC03, DC04, DC05, DC06, DC07, DC08, DC09, DC10, DC11, DC12,
+      DC13, DC14, DC15, DC16, DC17, DC18, DC19, DC20, DC21, DC22, DC23, DC24,
+      DC25;
   int Al, pred;
 
   /* Keep a local variable to avoid looking it up more than once */
@@ -431,18 +453,18 @@ decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
 
   /* Force some input to be done if we are getting ahead of the input. */
   while (cinfo->input_scan_number <= cinfo->output_scan_number &&
-         ! cinfo->inputctl->eoi_reached) {
+         !cinfo->inputctl->eoi_reached) {
     if (cinfo->input_scan_number == cinfo->output_scan_number) {
       /* If input is working on current scan, we ordinarily want it to
        * have completed the current row.  But if input scan is DC,
-       * we want it to keep one row ahead so that next block row's DC
+       * we want it to keep two rows ahead so that next two block rows' DC
        * values are up to date.
        */
-      JDIMENSION delta = (cinfo->Ss == 0) ? 1 : 0;
-      if (cinfo->input_iMCU_row > cinfo->output_iMCU_row+delta)
+      JDIMENSION delta = (cinfo->Ss == 0) ? 2 : 0;
+      if (cinfo->input_iMCU_row > cinfo->output_iMCU_row + delta)
         break;
     }
-    if ((*cinfo->inputctl->consume_input)(cinfo) == JPEG_SUSPENDED)
+    if ((*cinfo->inputctl->consume_input) (cinfo) == JPEG_SUSPENDED)
       return JPEG_SUSPENDED;
   }
 
@@ -450,37 +472,56 @@ decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
        ci++, compptr++) {
     /* Don't bother to IDCT an uninteresting component. */
-    if (! compptr->component_needed)
+    if (!compptr->component_needed)
       continue;
     /* Count non-dummy DCT block rows in this iMCU row. */
-    if (cinfo->output_iMCU_row < last_iMCU_row) {
+    if (cinfo->output_iMCU_row < last_iMCU_row - 1) {
+      block_rows = compptr->v_samp_factor;
+      access_rows = block_rows * 3; /* this and next two iMCU rows */
+    } else if (cinfo->output_iMCU_row < last_iMCU_row) {
       block_rows = compptr->v_samp_factor;
       access_rows = block_rows * 2; /* this and next iMCU row */
-      last_row = FALSE;
     } else {
       /* NB: can't use last_row_height here; it is input-side-dependent! */
-      block_rows = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
+      block_rows = (int)(compptr->height_in_blocks % compptr->v_samp_factor);
       if (block_rows == 0) block_rows = compptr->v_samp_factor;
       access_rows = block_rows; /* this iMCU row only */
-      last_row = TRUE;
     }
     /* Align the virtual buffer for this component. */
-    if (cinfo->output_iMCU_row > 0) {
-      access_rows += compptr->v_samp_factor; /* prior iMCU row too */
+    if (cinfo->output_iMCU_row > 1) {
+      access_rows += 2 * compptr->v_samp_factor; /* prior two iMCU rows too */
+      buffer = (*cinfo->mem->access_virt_barray)
+        ((j_common_ptr)cinfo, coef->whole_image[ci],
+         (cinfo->output_iMCU_row - 2) * compptr->v_samp_factor,
+         (JDIMENSION)access_rows, FALSE);
+      buffer += 2 * compptr->v_samp_factor; /* point to current iMCU row */
+    } else if (cinfo->output_iMCU_row > 0) {
       buffer = (*cinfo->mem->access_virt_barray)
-        ((j_common_ptr) cinfo, coef->whole_image[ci],
+        ((j_common_ptr)cinfo, coef->whole_image[ci],
          (cinfo->output_iMCU_row - 1) * compptr->v_samp_factor,
-         (JDIMENSION) access_rows, FALSE);
+         (JDIMENSION)access_rows, FALSE);
       buffer += compptr->v_samp_factor; /* point to current iMCU row */
-      first_row = FALSE;
     } else {
       buffer = (*cinfo->mem->access_virt_barray)
-        ((j_common_ptr) cinfo, coef->whole_image[ci],
-         (JDIMENSION) 0, (JDIMENSION) access_rows, FALSE);
-      first_row = TRUE;
+        ((j_common_ptr)cinfo, coef->whole_image[ci],
+         (JDIMENSION)0, (JDIMENSION)access_rows, FALSE);
     }
-    /* Fetch component-dependent info */
-    coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
+    /* Fetch component-dependent info.
+     * If the current scan is incomplete, then we use the component-dependent
+     * info from the previous scan.
+     */
+    if (cinfo->output_iMCU_row > cinfo->master->last_good_iMCU_row)
+      coef_bits =
+        coef->coef_bits_latch + ((ci + cinfo->num_components) * SAVED_COEFS);
+    else
+      coef_bits = coef->coef_bits_latch + (ci * SAVED_COEFS);
+
+    /* We only do DC interpolation if no AC coefficient data is available. */
+    change_dc =
+      coef_bits[1] == -1 && coef_bits[2] == -1 && coef_bits[3] == -1 &&
+      coef_bits[4] == -1 && coef_bits[5] == -1 && coef_bits[6] == -1 &&
+      coef_bits[7] == -1 && coef_bits[8] == -1 && coef_bits[9] == -1;
+
     quanttbl = compptr->quant_table;
     Q00 = quanttbl->quantval[0];
     Q01 = quanttbl->quantval[Q01_POS];
@@ -488,124 +529,268 @@ decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
     Q20 = quanttbl->quantval[Q20_POS];
     Q11 = quanttbl->quantval[Q11_POS];
     Q02 = quanttbl->quantval[Q02_POS];
+    if (change_dc) {
+      Q03 = quanttbl->quantval[Q03_POS];
+      Q12 = quanttbl->quantval[Q12_POS];
+      Q21 = quanttbl->quantval[Q21_POS];
+      Q30 = quanttbl->quantval[Q30_POS];
+    }
     inverse_DCT = cinfo->idct->inverse_DCT[ci];
     output_ptr = output_buf[ci];
     /* Loop over all DCT blocks to be processed. */
     for (block_row = 0; block_row < block_rows; block_row++) {
       buffer_ptr = buffer[block_row] + cinfo->master->first_MCU_col[ci];
-      if (first_row && block_row == 0)
+
+      if (block_row > 0 || cinfo->output_iMCU_row > 0)
+        prev_block_row =
+          buffer[block_row - 1] + cinfo->master->first_MCU_col[ci];
+      else
         prev_block_row = buffer_ptr;
+
+      if (block_row > 1 || cinfo->output_iMCU_row > 1)
+        prev_prev_block_row =
+          buffer[block_row - 2] + cinfo->master->first_MCU_col[ci];
+      else
+        prev_prev_block_row = prev_block_row;
+
+      if (block_row < block_rows - 1 || cinfo->output_iMCU_row < last_iMCU_row)
+        next_block_row =
+          buffer[block_row + 1] + cinfo->master->first_MCU_col[ci];
       else
-        prev_block_row = buffer[block_row-1];
-      if (last_row && block_row == block_rows-1)
         next_block_row = buffer_ptr;
+
+      if (block_row < block_rows - 2 ||
+          cinfo->output_iMCU_row < last_iMCU_row - 1)
+        next_next_block_row =
+          buffer[block_row + 2] + cinfo->master->first_MCU_col[ci];
       else
-        next_block_row = buffer[block_row+1];
+        next_next_block_row = next_block_row;
+
       /* We fetch the surrounding DC values using a sliding-register approach.
-       * Initialize all nine here so as to do the right thing on narrow pics.
+       * Initialize all 25 here so as to do the right thing on narrow pics.
        */
-      DC1 = DC2 = DC3 = (int) prev_block_row[0][0];
-      DC4 = DC5 = DC6 = (int) buffer_ptr[0][0];
-      DC7 = DC8 = DC9 = (int) next_block_row[0][0];
+      DC01 = DC02 = DC03 = DC04 = DC05 = (int)prev_prev_block_row[0][0];
+      DC06 = DC07 = DC08 = DC09 = DC10 = (int)prev_block_row[0][0];
+      DC11 = DC12 = DC13 = DC14 = DC15 = (int)buffer_ptr[0][0];
+      DC16 = DC17 = DC18 = DC19 = DC20 = (int)next_block_row[0][0];
+      DC21 = DC22 = DC23 = DC24 = DC25 = (int)next_next_block_row[0][0];
       output_col = 0;
       last_block_column = compptr->width_in_blocks - 1;
       for (block_num = cinfo->master->first_MCU_col[ci];
            block_num <= cinfo->master->last_MCU_col[ci]; block_num++) {
         /* Fetch current DCT block into workspace so we can modify it. */
-        jcopy_block_row(buffer_ptr, (JBLOCKROW) workspace, (JDIMENSION) 1);
+        jcopy_block_row(buffer_ptr, (JBLOCKROW)workspace, (JDIMENSION)1);
         /* Update DC values */
-        if (block_num < last_block_column) {
-          DC3 = (int) prev_block_row[1][0];
-          DC6 = (int) buffer_ptr[1][0];
-          DC9 = (int) next_block_row[1][0];
+        if (block_num == cinfo->master->first_MCU_col[ci] &&
+            block_num < last_block_column) {
+          DC04 = (int)prev_prev_block_row[1][0];
+          DC09 = (int)prev_block_row[1][0];
+          DC14 = (int)buffer_ptr[1][0];
+          DC19 = (int)next_block_row[1][0];
+          DC24 = (int)next_next_block_row[1][0];
+        }
+        if (block_num + 1 < last_block_column) {
+          DC05 = (int)prev_prev_block_row[2][0];
+          DC10 = (int)prev_block_row[2][0];
+          DC15 = (int)buffer_ptr[2][0];
+          DC20 = (int)next_block_row[2][0];
+          DC25 = (int)next_next_block_row[2][0];
         }
-        /* Compute coefficient estimates per K.8.
-         * An estimate is applied only if coefficient is still zero,
-         * and is not known to be fully accurate.
+        /* If DC interpolation is enabled, compute coefficient estimates using
+         * a Gaussian-like kernel, keeping the averages of the DC values.
+         *
+         * If DC interpolation is disabled, compute coefficient estimates using
+         * an algorithm similar to the one described in Section K.8 of the JPEG
+         * standard, except applied to a 5x5 window rather than a 3x3 window.
+         *
+         * An estimate is applied only if the coefficient is still zero and is
+         * not known to be fully accurate.
          */
         /* AC01 */
-        if ((Al=coef_bits[1]) != 0 && workspace[1] == 0) {
-          num = 36 * Q00 * (DC4 - DC6);
+        if ((Al = coef_bits[1]) != 0 && workspace[1] == 0) {
+          num = Q00 * (change_dc ?
+                (-DC01 - DC02 + DC04 + DC05 - 3 * DC06 + 13 * DC07 -
+                 13 * DC09 + 3 * DC10 - 3 * DC11 + 38 * DC12 - 38 * DC14 +
+                 3 * DC15 - 3 * DC16 + 13 * DC17 - 13 * DC19 + 3 * DC20 -
+                 DC21 - DC22 + DC24 + DC25) :
+                (-7 * DC11 + 50 * DC12 - 50 * DC14 + 7 * DC15));
           if (num >= 0) {
-            pred = (int) (((Q01<<7) + num) / (Q01<<8));
-            if (Al > 0 && pred >= (1<<Al))
-              pred = (1<<Al)-1;
+            pred = (int)(((Q01 << 7) + num) / (Q01 << 8));
+            if (Al > 0 && pred >= (1 << Al))
+              pred = (1 << Al) - 1;
           } else {
-            pred = (int) (((Q01<<7) - num) / (Q01<<8));
-            if (Al > 0 && pred >= (1<<Al))
-              pred = (1<<Al)-1;
+            pred = (int)(((Q01 << 7) - num) / (Q01 << 8));
+            if (Al > 0 && pred >= (1 << Al))
+              pred = (1 << Al) - 1;
             pred = -pred;
           }
-          workspace[1] = (JCOEF) pred;
+          workspace[1] = (JCOEF)pred;
         }
         /* AC10 */
-        if ((Al=coef_bits[2]) != 0 && workspace[8] == 0) {
-          num = 36 * Q00 * (DC2 - DC8);
+        if ((Al = coef_bits[2]) != 0 && workspace[8] == 0) {
+          num = Q00 * (change_dc ?
+                (-DC01 - 3 * DC02 - 3 * DC03 - 3 * DC04 - DC05 - DC06 +
+                 13 * DC07 + 38 * DC08 + 13 * DC09 - DC10 + DC16 -
+                 13 * DC17 - 38 * DC18 - 13 * DC19 + DC20 + DC21 +
+                 3 * DC22 + 3 * DC23 + 3 * DC24 + DC25) :
+                (-7 * DC03 + 50 * DC08 - 50 * DC18 + 7 * DC23));
           if (num >= 0) {
-            pred = (int) (((Q10<<7) + num) / (Q10<<8));
-            if (Al > 0 && pred >= (1<<Al))
-              pred = (1<<Al)-1;
+            pred = (int)(((Q10 << 7) + num) / (Q10 << 8));
+            if (Al > 0 && pred >= (1 << Al))
+              pred = (1 << Al) - 1;
           } else {
-            pred = (int) (((Q10<<7) - num) / (Q10<<8));
-            if (Al > 0 && pred >= (1<<Al))
-              pred = (1<<Al)-1;
+            pred = (int)(((Q10 << 7) - num) / (Q10 << 8));
+            if (Al > 0 && pred >= (1 << Al))
+              pred = (1 << Al) - 1;
             pred = -pred;
           }
-          workspace[8] = (JCOEF) pred;
+          workspace[8] = (JCOEF)pred;
         }
         /* AC20 */
-        if ((Al=coef_bits[3]) != 0 && workspace[16] == 0) {
-          num = 9 * Q00 * (DC2 + DC8 - 2*DC5);
+        if ((Al = coef_bits[3]) != 0 && workspace[16] == 0) {
+          num = Q00 * (change_dc ?
+                (DC03 + 2 * DC07 + 7 * DC08 + 2 * DC09 - 5 * DC12 - 14 * DC13 -
+                 5 * DC14 + 2 * DC17 + 7 * DC18 + 2 * DC19 + DC23) :
+                (-DC03 + 13 * DC08 - 24 * DC13 + 13 * DC18 - DC23));
           if (num >= 0) {
-            pred = (int) (((Q20<<7) + num) / (Q20<<8));
-            if (Al > 0 && pred >= (1<<Al))
-              pred = (1<<Al)-1;
+            pred = (int)(((Q20 << 7) + num) / (Q20 << 8));
+            if (Al > 0 && pred >= (1 << Al))
+              pred = (1 << Al) - 1;
           } else {
-            pred = (int) (((Q20<<7) - num) / (Q20<<8));
-            if (Al > 0 && pred >= (1<<Al))
-              pred = (1<<Al)-1;
+            pred = (int)(((Q20 << 7) - num) / (Q20 << 8));
+            if (Al > 0 && pred >= (1 << Al))
+              pred = (1 << Al) - 1;
             pred = -pred;
           }
-          workspace[16] = (JCOEF) pred;
+          workspace[16] = (JCOEF)pred;
         }
         /* AC11 */
-        if ((Al=coef_bits[4]) != 0 && workspace[9] == 0) {
-          num = 5 * Q00 * (DC1 - DC3 - DC7 + DC9);
+        if ((Al = coef_bits[4]) != 0 && workspace[9] == 0) {
+          num = Q00 * (change_dc ?
+                (-DC01 + DC05 + 9 * DC07 - 9 * DC09 - 9 * DC17 +
+                 9 * DC19 + DC21 - DC25) :
+                (DC10 + DC16 - 10 * DC17 + 10 * DC19 - DC02 - DC20 + DC22 -
+                 DC24 + DC04 - DC06 + 10 * DC07 - 10 * DC09));
           if (num >= 0) {
-            pred = (int) (((Q11<<7) + num) / (Q11<<8));
-            if (Al > 0 && pred >= (1<<Al))
-              pred = (1<<Al)-1;
+            pred = (int)(((Q11 << 7) + num) / (Q11 << 8));
+            if (Al > 0 && pred >= (1 << Al))
+              pred = (1 << Al) - 1;
           } else {
-            pred = (int) (((Q11<<7) - num) / (Q11<<8));
-            if (Al > 0 && pred >= (1<<Al))
-              pred = (1<<Al)-1;
+            pred = (int)(((Q11 << 7) - num) / (Q11 << 8));
+            if (Al > 0 && pred >= (1 << Al))
+              pred = (1 << Al) - 1;
             pred = -pred;
           }
-          workspace[9] = (JCOEF) pred;
+          workspace[9] = (JCOEF)pred;
         }
         /* AC02 */
-        if ((Al=coef_bits[5]) != 0 && workspace[2] == 0) {
-          num = 9 * Q00 * (DC4 + DC6 - 2*DC5);
+        if ((Al = coef_bits[5]) != 0 && workspace[2] == 0) {
+          num = Q00 * (change_dc ?
+                (2 * DC07 - 5 * DC08 + 2 * DC09 + DC11 + 7 * DC12 - 14 * DC13 +
+                 7 * DC14 + DC15 + 2 * DC17 - 5 * DC18 + 2 * DC19) :
+                (-DC11 + 13 * DC12 - 24 * DC13 + 13 * DC14 - DC15));
           if (num >= 0) {
-            pred = (int) (((Q02<<7) + num) / (Q02<<8));
-            if (Al > 0 && pred >= (1<<Al))
-              pred = (1<<Al)-1;
+            pred = (int)(((Q02 << 7) + num) / (Q02 << 8));
+            if (Al > 0 && pred >= (1 << Al))
+              pred = (1 << Al) - 1;
           } else {
-            pred = (int) (((Q02<<7) - num) / (Q02<<8));
-            if (Al > 0 && pred >= (1<<Al))
-              pred = (1<<Al)-1;
+            pred = (int)(((Q02 << 7) - num) / (Q02 << 8));
+            if (Al > 0 && pred >= (1 << Al))
+              pred = (1 << Al) - 1;
             pred = -pred;
           }
-          workspace[2] = (JCOEF) pred;
+          workspace[2] = (JCOEF)pred;
         }
+        if (change_dc) {
+          /* AC03 */
+          if ((Al = coef_bits[6]) != 0 && workspace[3] == 0) {
+            num = Q00 * (DC07 - DC09 + 2 * DC12 - 2 * DC14 + DC17 - DC19);
+            if (num >= 0) {
+              pred = (int)(((Q03 << 7) + num) / (Q03 << 8));
+              if (Al > 0 && pred >= (1 << Al))
+                pred = (1 << Al) - 1;
+            } else {
+              pred = (int)(((Q03 << 7) - num) / (Q03 << 8));
+              if (Al > 0 && pred >= (1 << Al))
+                pred = (1 << Al) - 1;
+              pred = -pred;
+            }
+            workspace[3] = (JCOEF)pred;
+          }
+          /* AC12 */
+          if ((Al = coef_bits[7]) != 0 && workspace[10] == 0) {
+            num = Q00 * (DC07 - 3 * DC08 + DC09 - DC17 + 3 * DC18 - DC19);
+            if (num >= 0) {
+              pred = (int)(((Q12 << 7) + num) / (Q12 << 8));
+              if (Al > 0 && pred >= (1 << Al))
+                pred = (1 << Al) - 1;
+            } else {
+              pred = (int)(((Q12 << 7) - num) / (Q12 << 8));
+              if (Al > 0 && pred >= (1 << Al))
+                pred = (1 << Al) - 1;
+              pred = -pred;
+            }
+            workspace[10] = (JCOEF)pred;
+          }
+          /* AC21 */
+          if ((Al = coef_bits[8]) != 0 && workspace[17] == 0) {
+            num = Q00 * (DC07 - DC09 - 3 * DC12 + 3 * DC14 + DC17 - DC19);
+            if (num >= 0) {
+              pred = (int)(((Q21 << 7) + num) / (Q21 << 8));
+              if (Al > 0 && pred >= (1 << Al))
+                pred = (1 << Al) - 1;
+            } else {
+              pred = (int)(((Q21 << 7) - num) / (Q21 << 8));
+              if (Al > 0 && pred >= (1 << Al))
+                pred = (1 << Al) - 1;
+              pred = -pred;
+            }
+            workspace[17] = (JCOEF)pred;
+          }
+          /* AC30 */
+          if ((Al = coef_bits[9]) != 0 && workspace[24] == 0) {
+            num = Q00 * (DC07 + 2 * DC08 + DC09 - DC17 - 2 * DC18 - DC19);
+            if (num >= 0) {
+              pred = (int)(((Q30 << 7) + num) / (Q30 << 8));
+              if (Al > 0 && pred >= (1 << Al))
+                pred = (1 << Al) - 1;
+            } else {
+              pred = (int)(((Q30 << 7) - num) / (Q30 << 8));
+              if (Al > 0 && pred >= (1 << Al))
+                pred = (1 << Al) - 1;
+              pred = -pred;
+            }
+            workspace[24] = (JCOEF)pred;
+          }
+          /* coef_bits[0] is non-negative.  Otherwise this function would not
+           * be called.
+           */
+          num = Q00 *
+                (-2 * DC01 - 6 * DC02 - 8 * DC03 - 6 * DC04 - 2 * DC05 -
+                 6 * DC06 + 6 * DC07 + 42 * DC08 + 6 * DC09 - 6 * DC10 -
+                 8 * DC11 + 42 * DC12 + 152 * DC13 + 42 * DC14 - 8 * DC15 -
+                 6 * DC16 + 6 * DC17 + 42 * DC18 + 6 * DC19 - 6 * DC20 -
+                 2 * DC21 - 6 * DC22 - 8 * DC23 - 6 * DC24 - 2 * DC25);
+          if (num >= 0) {
+            pred = (int)(((Q00 << 7) + num) / (Q00 << 8));
+          } else {
+            pred = (int)(((Q00 << 7) - num) / (Q00 << 8));
+            pred = -pred;
+          }
+          workspace[0] = (JCOEF)pred;
+        }  /* change_dc */
+
         /* OK, do the IDCT */
-        (*inverse_DCT) (cinfo, compptr, (JCOEFPTR) workspace,
-                        output_ptr, output_col);
+        (*inverse_DCT) (cinfo, compptr, (JCOEFPTR)workspace, output_ptr,
+                        output_col);
         /* Advance for next column */
-        DC1 = DC2; DC2 = DC3;
-        DC4 = DC5; DC5 = DC6;
-        DC7 = DC8; DC8 = DC9;
-        buffer_ptr++, prev_block_row++, next_block_row++;
+        DC01 = DC02;  DC02 = DC03;  DC03 = DC04;  DC04 = DC05;
+        DC06 = DC07;  DC07 = DC08;  DC08 = DC09;  DC09 = DC10;
+        DC11 = DC12;  DC12 = DC13;  DC13 = DC14;  DC14 = DC15;
+        DC16 = DC17;  DC17 = DC18;  DC18 = DC19;  DC19 = DC20;
+        DC21 = DC22;  DC22 = DC23;  DC23 = DC24;  DC24 = DC25;
+        buffer_ptr++, prev_block_row++, next_block_row++,
+          prev_prev_block_row++, next_next_block_row++;
         output_col += compptr->_DCT_scaled_size;
       }
       output_ptr += compptr->_DCT_scaled_size;
@@ -625,14 +810,14 @@ decompress_smooth_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
  */
 
 GLOBAL(void)
-jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
+jinit_d_coef_controller(j_decompress_ptr cinfo, boolean need_full_buffer)
 {
   my_coef_ptr coef;
 
   coef = (my_coef_ptr)
-    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+    (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
                                 sizeof(my_coef_controller));
-  cinfo->coef = (struct jpeg_d_coef_controller *) coef;
+  cinfo->coef = (struct jpeg_d_coef_controller *)coef;
   coef->pub.start_input_pass = start_input_pass;
   coef->pub.start_output_pass = start_output_pass;
 #ifdef BLOCK_SMOOTHING_SUPPORTED
@@ -654,15 +839,15 @@ jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
 #ifdef BLOCK_SMOOTHING_SUPPORTED
       /* If block smoothing could be used, need a bigger window */
       if (cinfo->progressive_mode)
-        access_rows *= 3;
+        access_rows *= 5;
 #endif
       coef->whole_image[ci] = (*cinfo->mem->request_virt_barray)
-        ((j_common_ptr) cinfo, JPOOL_IMAGE, TRUE,
-         (JDIMENSION) jround_up((long) compptr->width_in_blocks,
-                                (long) compptr->h_samp_factor),
-         (JDIMENSION) jround_up((long) compptr->height_in_blocks,
-                                (long) compptr->v_samp_factor),
-         (JDIMENSION) access_rows);
+        ((j_common_ptr)cinfo, JPOOL_IMAGE, TRUE,
+         (JDIMENSION)jround_up((long)compptr->width_in_blocks,
+                               (long)compptr->h_samp_factor),
+         (JDIMENSION)jround_up((long)compptr->height_in_blocks,
+                               (long)compptr->v_samp_factor),
+         (JDIMENSION)access_rows);
     }
     coef->pub.consume_data = consume_data;
     coef->pub.decompress_data = decompress_data;
@@ -676,7 +861,7 @@ jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
     int i;
 
     buffer = (JBLOCKROW)
-      (*cinfo->mem->alloc_large) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+      (*cinfo->mem->alloc_large) ((j_common_ptr)cinfo, JPOOL_IMAGE,
                                   D_MAX_BLOCKS_IN_MCU * sizeof(JBLOCK));
     for (i = 0; i < D_MAX_BLOCKS_IN_MCU; i++) {
       coef->MCU_buffer[i] = buffer + i;
@@ -688,6 +873,6 @@ jinit_d_coef_controller (j_decompress_ptr cinfo, boolean need_full_buffer)
 
   /* Allocate the workspace buffer */
   coef->workspace = (JCOEF *)
-    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
+    (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
                                 sizeof(JCOEF) * DCTSIZE2);
 }