prepare java decoder for transpilation to Kotlin

PiperOrigin-RevId: 601023149

Author: eustas

java/org/brotli/dec/Decode.java

@@ -351,7 +351,7 @@ private static void decodeMetaBlockLength(State s) {
       if (sizeBytes == 0) {
         return;
       }
-      for (int i = 0; i < sizeBytes; i++) {
+      for (int i = 0; i < sizeBytes; ++i) {
         BitReader.fillBitWindow(s);
         final int bits = BitReader.readFewBits(s, 8);
         if (bits == 0 && i + 1 == sizeBytes && sizeBytes > 1) {
@@ -360,7 +360,7 @@ private static void decodeMetaBlockLength(State s) {
         s.metaBlockLength |= bits << (i * 8);
       }
     } else {
-      for (int i = 0; i < sizeNibbles; i++) {
+      for (int i = 0; i < sizeNibbles; ++i) {
         BitReader.fillBitWindow(s);
         final int bits = BitReader.readFewBits(s, 4);
         if (bits == 0 && i + 1 == sizeNibbles && sizeNibbles > 4) {
@@ -405,18 +405,19 @@ private static int readBlockLength(int[] tableGroup, int tableIdx, State s) {
 
   private static void moveToFront(int[] v, int index) {
     final int value = v[index];
-    for (; index > 0; index--) {
+    while (index > 0) {
       v[index] = v[index - 1];
+      index--;
     }
     v[0] = value;
   }
 
   private static void inverseMoveToFrontTransform(byte[] v, int vLen) {
     final int[] mtf = new int[256];
-    for (int i = 0; i < 256; i++) {
+    for (int i = 0; i < 256; ++i) {
       mtf[i] = i;
     }
-    for (int i = 0; i < vLen; i++) {
+    for (int i = 0; i < vLen; ++i) {
       final int index = v[i] & 0xFF;
       v[i] = (byte) mtf[index];
       if (index != 0) {
@@ -470,7 +471,7 @@ private static void readHuffmanCodeLengths(
         if (symbol + repeatDelta > numSymbols) {
           throw new BrotliRuntimeException("symbol + repeatDelta > numSymbols"); // COV_NF_LINE
         }
-        for (int i = 0; i < repeatDelta; i++) {
+        for (int i = 0; i < repeatDelta; ++i) {
           codeLengths[symbol++] = repeatCodeLen;
         }
         if (repeatCodeLen != 0) {
@@ -507,7 +508,7 @@ private static int readSimpleHuffmanCode(int alphabetSizeMax, int alphabetSizeLi
     final int maxBits = 1 + log2floor(alphabetSizeMax - 1);
 
     final int numSymbols = BitReader.readFewBits(s, 2) + 1;
-    for (int i = 0; i < numSymbols; i++) {
+    for (int i = 0; i < numSymbols; ++i) {
       BitReader.fillBitWindow(s);
       final int symbol = BitReader.readFewBits(s, maxBits);
       if (symbol >= alphabetSizeLimit) {
@@ -569,7 +570,7 @@ private static int readComplexHuffmanCode(int alphabetSizeLimit, int skip,
     final int[] codeLengthCodeLengths = new int[CODE_LENGTH_CODES];
     int space = 32;
     int numCodes = 0;
-    for (int i = skip; i < CODE_LENGTH_CODES && space > 0; i++) {
+    for (int i = skip; i < CODE_LENGTH_CODES; ++i) {
       final int codeLenIdx = CODE_LENGTH_CODE_ORDER[i];
       BitReader.fillBitWindow(s);
       final int p = BitReader.peekBits(s) & 15;
@@ -580,6 +581,7 @@ private static int readComplexHuffmanCode(int alphabetSizeLimit, int skip,
       if (v != 0) {
         space -= (32 >> v);
         numCodes++;
+        if (space <= 0) break;
       }
     }
     if (space != 0 && numCodes != 1) {
@@ -630,7 +632,8 @@ private static int decodeContextMap(int contextMapSize, byte[] contextMap, State
     final int[] table = new int[tableSize + 1];
     final int tableIdx = table.length - 1;
     readHuffmanCode(alphabetSize, alphabetSize, table, tableIdx, s);
-    for (int i = 0; i < contextMapSize; ) {
+    int i = 0;
+    while (i < contextMapSize) {
       BitReader.readMoreInput(s);
       BitReader.fillBitWindow(s);
       final int code = readSymbol(table, tableIdx, s);
@@ -829,22 +832,24 @@ private static void readMetablockHuffmanCodesAndContextMaps(State s) {
     s.numDirectDistanceCodes = BitReader.readFewBits(s, 4) << s.distancePostfixBits;
     // TODO(eustas): Reuse?
     s.contextModes = new byte[s.numLiteralBlockTypes];
-    for (int i = 0; i < s.numLiteralBlockTypes;) {
+    int i = 0;
+    while (i < s.numLiteralBlockTypes) {
       /* Ensure that less than 256 bits read between readMoreInput. */
       final int limit = Math.min(i + 96, s.numLiteralBlockTypes);
-      for (; i < limit; ++i) {
+      while (i < limit) {
         BitReader.fillBitWindow(s);
         s.contextModes[i] = (byte) BitReader.readFewBits(s, 2);
+        i++;
       }
       BitReader.readMoreInput(s);
     }
 
     // TODO(eustas): Reuse?
-    s.contextMap = new byte[s.numLiteralBlockTypes << LITERAL_CONTEXT_BITS];
-    final int numLiteralTrees = decodeContextMap(s.numLiteralBlockTypes << LITERAL_CONTEXT_BITS,
-        s.contextMap, s);
+    final int contextMapLength = s.numLiteralBlockTypes << LITERAL_CONTEXT_BITS;
+    s.contextMap = new byte[contextMapLength];
+    final int numLiteralTrees = decodeContextMap(contextMapLength, s.contextMap, s);
     s.trivialLiteralContext = 1;
-    for (int j = 0; j < s.numLiteralBlockTypes << LITERAL_CONTEXT_BITS; j++) {
+    for (int j = 0; j < contextMapLength; ++j) {
       if (s.contextMap[j] != j >> LITERAL_CONTEXT_BITS) {
         s.trivialLiteralContext = 0;
         break;
@@ -1253,7 +1258,8 @@ static void decompress(State s) {
           final int dstEnd = dst + copyLength;
           if ((srcEnd < ringBufferMask) && (dstEnd < ringBufferMask)) {
             if (copyLength < 12 || (srcEnd > dst && dstEnd > src)) {
-              for (int k = 0; k < copyLength; k += 4) {
+              final int numQuads = (copyLength + 3) >> 2;
+              for (int k = 0; k < numQuads; ++k) {
                 ringBuffer[dst++] = ringBuffer[src++];
                 ringBuffer[dst++] = ringBuffer[src++];
                 ringBuffer[dst++] = ringBuffer[src++];
@@ -1266,7 +1272,7 @@ static void decompress(State s) {
             s.metaBlockLength -= copyLength;
             s.pos += copyLength;
           } else {
-            for (; s.j < s.copyLength;) {
+            while (s.j < s.copyLength) {
               ringBuffer[s.pos] =
                   ringBuffer[(s.pos - s.distance) & ringBufferMask];
               s.metaBlockLength--;

java/org/brotli/dec/DictionaryData.java

@@ -43,10 +43,10 @@ private static void unpackDictionaryData(ByteBuffer dictionary, String data0, St
 
     // Toggle high bit using run-length delta encoded "skipFlip".
     int offset = 0;
-    final int n = skipFlip.length();
-    for (int i = 0; i < n; i += 2) {
-      final int skip = skipFlip.charAt(i) - 36;
-      final int flip = skipFlip.charAt(i + 1) - 36;
+    final int n = skipFlip.length() >> 1;
+    for (int i = 0; i < n; ++i) {
+      final int skip = skipFlip.charAt(2 * i) - 36;
+      final int flip = skipFlip.charAt(2 * i + 1) - 36;
       for (int j = 0; j < skip; ++j) {
         dict[offset] ^= 3;
         offset++;

java/org/brotli/dec/Huffman.java

@@ -64,28 +64,26 @@ private static int nextTableBitSize(int[] count, int len, int rootBits) {
   static int buildHuffmanTable(int[] tableGroup, int tableIdx, int rootBits, int[] codeLengths,
       int codeLengthsSize) {
     final int tableOffset = tableGroup[tableIdx];
-    int key; // Reversed prefix code.
     final int[] sorted = new int[codeLengthsSize]; // Symbols sorted by code length.
     // TODO(eustas): fill with zeroes?
     final int[] count = new int[MAX_LENGTH + 1]; // Number of codes of each length.
     final int[] offset = new int[MAX_LENGTH + 1]; // Offsets in sorted table for each length.
-    int symbol;
 
     // Build histogram of code lengths.
-    for (symbol = 0; symbol < codeLengthsSize; symbol++) {
-      count[codeLengths[symbol]]++;
+    for (int sym = 0; sym < codeLengthsSize; ++sym) {
+      count[codeLengths[sym]]++;
     }
 
     // Generate offsets into sorted symbol table by code length.
     offset[1] = 0;
-    for (int len = 1; len < MAX_LENGTH; len++) {
+    for (int len = 1; len < MAX_LENGTH; ++len) {
       offset[len + 1] = offset[len] + count[len];
     }
 
     // Sort symbols by length, by symbol order within each length.
-    for (symbol = 0; symbol < codeLengthsSize; symbol++) {
-      if (codeLengths[symbol] != 0) {
-        sorted[offset[codeLengths[symbol]]++] = symbol;
+    for (int sym = 0; sym < codeLengthsSize; ++sym) {
+      if (codeLengths[sym] != 0) {
+        sorted[offset[codeLengths[sym]]++] = sym;
       }
     }
 
@@ -95,29 +93,34 @@ static int buildHuffmanTable(int[] tableGroup, int tableIdx, int rootBits, int[]
 
     // Special case code with only one value.
     if (offset[MAX_LENGTH] == 1) {
-      for (key = 0; key < totalSize; key++) {
-        tableGroup[tableOffset + key] = sorted[0];
+      for (int k = 0; k < totalSize; ++k) {
+        tableGroup[tableOffset + k] = sorted[0];
       }
       return totalSize;
     }
 
     // Fill in root table.
-    key = 0;
-    symbol = 0;
-    for (int len = 1, step = 2; len <= rootBits; len++, step <<= 1) {
-      for (; count[len] > 0; count[len]--) {
+    int key = 0;  // Reversed prefix code.
+    int symbol = 0;
+    int step = 1;
+    for (int len = 1; len <= rootBits; ++len) {
+      step <<= 1;
+      while (count[len] > 0) {
         replicateValue(tableGroup, tableOffset + key, step, tableSize,
             len << 16 | sorted[symbol++]);
         key = getNextKey(key, len);
+        count[len]--;
       }
     }
 
     // Fill in 2nd level tables and add pointers to root table.
     final int mask = totalSize - 1;
     int low = -1;
     int currentOffset = tableOffset;
-    for (int len = rootBits + 1, step = 2; len <= MAX_LENGTH; len++, step <<= 1) {
-      for (; count[len] > 0; count[len]--) {
+    step = 1;
+    for (int len = rootBits + 1; len <= MAX_LENGTH; ++len) {
+      step <<= 1;
+      while (count[len] > 0) {
         if ((key & mask) != low) {
           currentOffset += tableSize;
           tableBits = nextTableBitSize(count, len, rootBits);
@@ -130,6 +133,7 @@ static int buildHuffmanTable(int[] tableGroup, int tableIdx, int rootBits, int[]
         replicateValue(tableGroup, currentOffset + (key >> rootBits), step, tableSize,
             (len - rootBits) << 16 | sorted[symbol++]);
         key = getNextKey(key, len);
+        count[len]--;
       }
     }
     return totalSize;