replaced integer * and % with shift operations, for performance

2 files changed, 14 insertions, 14 deletions

diff --git a/core/java/com/android/internal/util/BitwiseInputStream.java b/core/java/com/android/internal/util/BitwiseInputStream.java
index 5da3bc6..4757919 100644
--- a/core/java/com/android/internal/util/BitwiseInputStream.java
+++ b/core/java/com/android/internal/util/BitwiseInputStream.java
@@ -51,7 +51,7 @@ public class BitwiseInputStream {
      */
     public BitwiseInputStream(byte buf[]) {
         mBuf = buf;
-        mEnd = buf.length * 8;
+        mEnd = buf.length << 3;
         mPos = 0;
     }
 
@@ -70,13 +70,13 @@ public class BitwiseInputStream {
      * @return byte of read data (possibly partially filled, from lsb)
      */
     public byte read(int bits) throws AccessException {
-        int index = mPos / 8;
-        int offset = 16 - (mPos % 8) - bits;
+        int index = mPos >>> 3;
+        int offset = 16 - (mPos & 0x07) - bits;  // &7==%8
         if ((bits < 0) || (bits > 8) || ((mPos + bits) > mEnd)) {
             throw new AccessException("illegal read " +
                 "(pos " + mPos + ", end " + mEnd + ", bits " + bits + ")");
         }
-        int data = (mBuf[index] & 0xFF) << 8;
+        int data = (mBuf[index] & 0x00FF) << 8;
         if (offset < 8) data |= (mBuf[index + 1] & 0xFF);
         data >>>= offset;
         data &= (-1 >>> (32 - bits));
@@ -92,10 +92,10 @@ public class BitwiseInputStream {
      * @return newly allocated byte array of read data
      */
     public byte[] readByteArray(int bits) throws AccessException {
-        int bytes = (bits / 8) + ((bits % 8) > 0 ? 1 : 0);
+        int bytes = (bits >>> 3) + ((bits & 0x07) > 0 ? 1 : 0);  // &7==%8
         byte[] arr = new byte[bytes];
         for (int i = 0; i < bytes; i++) {
-            int increment = Math.min(8, bits - (i * 8));
+            int increment = Math.min(8, bits - (i << 3));
             arr[i] = (byte)(read(increment) << (8 - increment));
         }
         return arr;
diff --git a/core/java/com/android/internal/util/BitwiseOutputStream.java b/core/java/com/android/internal/util/BitwiseOutputStream.java
index 5941bf3..17f5c7c 100644
--- a/core/java/com/android/internal/util/BitwiseOutputStream.java
+++ b/core/java/com/android/internal/util/BitwiseOutputStream.java
@@ -51,7 +51,7 @@ public class BitwiseOutputStream {
      */
     public BitwiseOutputStream(int startingLength) {
         mBuf = new byte[startingLength];
-        mEnd = startingLength * 8;
+        mEnd = startingLength << 3;
         mPos = 0;
     }
 
@@ -61,7 +61,7 @@ public class BitwiseOutputStream {
      * @return newly allocated byte array
      */
     public byte[] toByteArray() {
-        int len = (mPos / 8) + ((mPos % 8) > 0 ? 1 : 0);
+        int len = (mPos >>> 3) + ((mPos & 0x07) > 0 ? 1 : 0);  // &7==%8
         byte[] newBuf = new byte[len];
         System.arraycopy(mBuf, 0, newBuf, 0, len);
         return newBuf;
@@ -74,8 +74,8 @@ public class BitwiseOutputStream {
      */
     private void possExpand(int bits) {
         if ((mPos + bits) < mEnd) return;
-        byte[] newBuf = new byte[((mPos + bits) * 2) / 8];
-        System.arraycopy(mBuf, 0, newBuf, 0, mEnd / 8);
+        byte[] newBuf = new byte[(mPos + bits) >>> 2];
+        System.arraycopy(mBuf, 0, newBuf, 0, mEnd >>> 3);
         mBuf = newBuf;
     }
 
@@ -91,12 +91,12 @@ public class BitwiseOutputStream {
         }
         possExpand(bits);
         data &= (-1 >>> (32 - bits));
-        int index = mPos / 8;
-        int offset = 16 - (mPos % 8) - bits;
+        int index = mPos >>> 3;
+        int offset = 16 - (mPos & 0x07) - bits;  // &7==%8
         data <<= offset;
         mPos += bits;
         mBuf[index] |= (data >>> 8);
-        if (offset < 8) mBuf[index + 1] |= (data & 0xFF);
+        if (offset < 8) mBuf[index + 1] |= (data & 0x00FF);
     }
 
     /**
@@ -107,7 +107,7 @@ public class BitwiseOutputStream {
      */
     public void writeByteArray(int bits, byte[] arr) throws AccessException {
         for (int i = 0; i < arr.length; i++) {
-            int increment = Math.min(8, bits - (i * 8));
+            int increment = Math.min(8, bits - (i << 3));
             if (increment > 0) {
                 write(increment, (byte)(arr[i] >>> (8 - increment)));
             }