MCT: force all components to 32 bit path is at least one must use 32 bit

Author: Grok Compression

.vscode/launch.json

@@ -877,7 +877,7 @@
             "args": [
                 //"${workspaceFolder}/build/bin/grk_decompress",
                 "-i",
-                "$HOME/temp/clusterfuzz-testcase-minimized-grk_decompress_fuzzer-6467774498275328",
+                "$HOME/temp/clusterfuzz-testcase-minimized-grk_decompress_fuzzer-4717825607663616",
                 "-d 0,0,1024,1024",
                  "-o",
                 "$HOME/temp/fuzz.pgx"

src/lib/core/point_transform/mct.cpp

@@ -718,7 +718,9 @@ void Mct::schedule_decompress_irrev(FlowComponent* flow, bool applyDcShift)
 {
   ScheduleInfo info(tile_, flow, image_->rows_per_task);
   genShift(applyDcShift ? 1 : 0, info.shiftInfo);
-  if(tile_->comps_[0].is16BitDwt())
+  // All 3 MCT components must agree on data type; use 16-bit only if all are 16-bit
+  if(tile_->comps_[0].is16BitDwt() && tile_->comps_[1].is16BitDwt() &&
+     tile_->comps_[2].is16BitDwt())
     HWY_DYNAMIC_DISPATCH(hwy_schedule_decompress_irrev16)(info);
   else
     HWY_DYNAMIC_DISPATCH(hwy_schedule_decompress_irrev)(info);
@@ -731,7 +733,9 @@ void Mct::schedule_decompress_rev(FlowComponent* flow, bool applyDcShift)
 {
   ScheduleInfo info(tile_, flow, image_->rows_per_task);
   genShift(applyDcShift ? 1 : 0, info.shiftInfo);
-  if(tile_->comps_[0].is16BitDwt())
+  // All 3 MCT components must agree on data type; use 16-bit only if all are 16-bit
+  if(tile_->comps_[0].is16BitDwt() && tile_->comps_[1].is16BitDwt() &&
+     tile_->comps_[2].is16BitDwt())
     HWY_DYNAMIC_DISPATCH(hwy_schedule_decompress_rev16)(info);
   else
     HWY_DYNAMIC_DISPATCH(hwy_schedule_decompress_rev)(info);

src/lib/core/tile_processor/TileProcessor.cpp

@@ -998,6 +998,30 @@ bool TileProcessor::createDecompressTileComponentWindows(void)
          GRK_INT_16)
         tileComp->setUse16BitDwt(true);
     }
+  }
+  // MCT operates on all 3 components with the same data type;
+  // if any MCT component is not 16-bit, force all to 32-bit
+  if(needsMctDecompress() && tcp_->mct_ == 1 && tile_->numcomps_ >= 3)
+  {
+    bool all16 = true;
+    for(uint16_t compno = 0; compno < 3; ++compno)
+    {
+      if(!tile_->comps_[compno].is16BitDwt())
+      {
+        all16 = false;
+        break;
+      }
+    }
+    if(!all16)
+    {
+      for(uint16_t compno = 0; compno < 3; ++compno)
+        tile_->comps_[compno].setUse16BitDwt(false);
+    }
+  }
+  for(uint16_t compno = 0; compno < tile_->numcomps_; ++compno)
+  {
+    auto imageComp = headerImage_->comps + compno;
+    auto tileComp = tile_->comps_ + compno;
     auto unreducedImageCompWindow =
         unreducedImageWindow_.scaleDownCeil(imageComp->dx, imageComp->dy);
     if(!tileComp->canCreateWindow(unreducedImageCompWindow))