/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.ddmlib.utils;

/**
 * Utility class providing array to int/long conversion for data received from devices through adb. 
 */
public final class ArrayHelper {

    /**
     * Swaps an unsigned value around, and puts the result in an array that can be sent to a device.
     * @param value The value to swap.
     * @param dest the destination array
     * @param offset the offset in the array where to put the swapped value.
     *      Array length must be at least offset + 4
     */
    public static void swap32bitsToArray(int value, byte[] dest, int offset) {
        dest[offset] = (byte)(value & 0x000000FF);
        dest[offset + 1] = (byte)((value & 0x0000FF00) >> 8);
        dest[offset + 2] = (byte)((value & 0x00FF0000) >> 16);
        dest[offset + 3] = (byte)((value & 0xFF000000) >> 24);
    }

    /**
     * Reads a signed 32 bit integer from an array coming from a device.
     * @param value the array containing the int
     * @param offset the offset in the array at which the int starts
     * @return the integer read from the array
     */
    public static int swap32bitFromArray(byte[] value, int offset) {
        int v = 0;
        v |= ((int)value[offset]) & 0x000000FF;
        v |= (((int)value[offset + 1]) & 0x000000FF) << 8;
        v |= (((int)value[offset + 2]) & 0x000000FF) << 16;
        v |= (((int)value[offset + 3]) & 0x000000FF) << 24;

        return v;
    }
    
    /**
     * Reads an unsigned 16 bit integer from an array coming from a device,
     * and returns it as an 'int'
     * @param value the array containing the 16 bit int (2 byte).
     * @param offset the offset in the array at which the int starts
     *      Array length must be at least offset + 2
     * @return the integer read from the array.
     */
    public static int swapU16bitFromArray(byte[] value, int offset) {
        int v = 0;
        v |= ((int)value[offset]) & 0x000000FF;
        v |= (((int)value[offset + 1]) & 0x000000FF) << 8;

        return v;
    }
    
    /**
     * Reads a signed 64 bit integer from an array coming from a device.
     * @param value the array containing the int
     * @param offset the offset in the array at which the int starts
     *      Array length must be at least offset + 8
     * @return the integer read from the array
     */
    public static long swap64bitFromArray(byte[] value, int offset) {
        long v = 0;
        v |= ((long)value[offset]) & 0x00000000000000FFL;
        v |= (((long)value[offset + 1]) & 0x00000000000000FFL) << 8;
        v |= (((long)value[offset + 2]) & 0x00000000000000FFL) << 16;
        v |= (((long)value[offset + 3]) & 0x00000000000000FFL) << 24;
        v |= (((long)value[offset + 4]) & 0x00000000000000FFL) << 32;
        v |= (((long)value[offset + 5]) & 0x00000000000000FFL) << 40;
        v |= (((long)value[offset + 6]) & 0x00000000000000FFL) << 48;
        v |= (((long)value[offset + 7]) & 0x00000000000000FFL) << 56;

        return v;
    }
}