1 /* 2 * BCJ filter for little endian ARM instructions 3 * 4 * Authors: Lasse Collin <lasse.collin (at) tukaani.org> 5 * Igor Pavlov <http://7-zip.org/> 6 * 7 * This file has been put into the public domain. 8 * You can do whatever you want with this file. 9 */ 10 11 package org.tukaani.xz.simple; 12 13 public final class ARM implements SimpleFilter { 14 private final boolean isEncoder; 15 private int pos; 16 17 public ARM(boolean isEncoder, int startPos) { 18 this.isEncoder = isEncoder; 19 pos = startPos + 8; 20 } 21 22 public int code(byte[] buf, int off, int len) { 23 int end = off + len - 4; 24 int i; 25 26 for (i = off; i <= end; i += 4) { 27 if ((buf[i + 3] & 0xFF) == 0xEB) { 28 int src = ((buf[i + 2] & 0xFF) << 16) 29 | ((buf[i + 1] & 0xFF) << 8) 30 | (buf[i] & 0xFF); 31 src <<= 2; 32 33 int dest; 34 if (isEncoder) 35 dest = src + (pos + i - off); 36 else 37 dest = src - (pos + i - off); 38 39 dest >>>= 2; 40 buf[i + 2] = (byte)(dest >>> 16); 41 buf[i + 1] = (byte)(dest >>> 8); 42 buf[i] = (byte)dest; 43 } 44 } 45 46 i -= off; 47 pos += i; 48 return i; 49 } 50 } 51
