Slightly better header encoding

NeRdTheNed · Aug 19, 2023 · 9c85db9 · 9c85db9
1 parent 644fb8d
commit 9c85db9
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Showing 2 changed files with 35 additions and 1 deletion.
diff --git a/deft4j-base/src/main/java/com/github/NeRdTheNed/deft4j/deflate/DeflateBlockHuffman.java b/deft4j-base/src/main/java/com/github/NeRdTheNed/deft4j/deflate/DeflateBlockHuffman.java
@@ -730,7 +730,15 @@ public void recodeHuffman() {
         }
 
         final Huffman newLit = new Huffman(new HuffmanTree(litFreq, 15).getTable());
-        final Huffman newDist = handleZero ? new Huffman(new HuffmanTable(1)) : new Huffman(new HuffmanTree(distFreq, 15).getTable());
+        // TODO This code isn't good
+        final boolean handleOne = !handleZero && (MIN_DIST_CODES <= 1) && (Util.checkNonZero(distFreq) <= 1);
+        final Huffman newDist = (handleZero || handleOne) ? new Huffman(new HuffmanTable(handleZero ? 1 : realLastNonZeroDist)) : new Huffman(new HuffmanTree(distFreq, 15).getTable());
+
+        if (handleOne) {
+            newDist.table.codeLen[realLastNonZeroDist - 1] = 1;
+            newDist.table.code[realLastNonZeroDist - 1] = 0;
+        }
+
         recodeToHuffman(newLit, newDist);
     }
 

diff --git a/deft4j-base/src/main/java/com/github/NeRdTheNed/deft4j/util/Util.java b/deft4j-base/src/main/java/com/github/NeRdTheNed/deft4j/util/Util.java
@@ -38,6 +38,32 @@ public static boolean checkAllZero(byte[] bytes) {
         return true;
     }
 
+    /** Count number of non-zero values in the array */
+    public static int checkNonZero(byte[] bytes) {
+        int count = 0;
+
+        for (final byte b : bytes) {
+            if (b != 0) {
+                count++;
+            }
+        }
+
+        return count;
+    }
+
+    /** Count number of non-zero values in the array */
+    public static int checkNonZero(int[] ints) {
+        int count = 0;
+
+        for (final int i : ints) {
+            if (i != 0) {
+                count++;
+            }
+        }
+
+        return count;
+    }
+
     /** Creates a new array with the contents of both arrays */
     public static int[] combine(int[] a1, int[] a2) {
         final int[] combined = Arrays.copyOf(a1, a1.length + a2.length);