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package com.payneteasy.tlv;

public class HexUtil {

    private static final char[] CHARS_TABLES = "0123456789ABCDEF".toCharArray();
    static final byte[] BYTES = new byte[128];

    static {
        for (int i = 0; i < 10; i++) {
            BYTES['0' + i] = (byte) i;
            BYTES['A' + i] = (byte) (10 + i);
            BYTES['a' + i] = (byte) (10 + i);
        }
    }

    public static String toHexString(byte[] aBytes) {
        return toHexString(aBytes, 0, aBytes.length);
    }

    public static String toFormattedHexString(byte[] aBytes) {
        return toFormattedHexString(aBytes, 0, aBytes.length);
    }

    public static String toHexString(byte[] aBytes, int aLength) {
        return toHexString(aBytes, 0, aLength);
    }

    public static byte[] parseHex(String aHexString) {
        char[] src = aHexString.replace("\n", "").replace(" ", "").toUpperCase().toCharArray();
        byte[] dst = new byte[src.length / 2];

        for (int si = 0, di = 0; di < dst.length; di++) {
            byte high = BYTES[src[si++] & 0x7f];
            byte low  = BYTES[src[si++] & 0x7f];
            dst[di] = (byte) ((high << 4) + low);
        }

        return dst;
    }

    public static String toFormattedHexString(byte[] aBytes, int aOffset, int aLength) {
        StringBuilder sb = new StringBuilder();
        sb.append("[");
        sb.append(aLength);
        sb.append("] :");
        for (int si = aOffset, di = 0; si < aOffset+aLength; si++, di++) {
            byte b = aBytes[si];
            if (di % 4 == 0) {
                sb.append("  ");
            } else {
                sb.append(' ');
            }
            sb.append( CHARS_TABLES[(b & 0xf0) >>> 4] );
            sb.append( CHARS_TABLES[(b & 0x0f)] );

        }

        return sb.toString();

    }

    public static String toHexString(byte[] aBytes, int aOffset, int aLength) {
        char[] dst   = new char[aLength * 2];

        for (int si = aOffset, di = 0; si < aOffset+aLength; si++) {
            byte b = aBytes[si];
            dst[di++] = CHARS_TABLES[(b & 0xf0) >>> 4];
            dst[di++] = CHARS_TABLES[(b & 0x0f)];
        }

        return new String(dst);
    }

}