1 /* 2 * BCJ filter for big endian PowerPC 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 PowerPC implements SimpleFilter { 14 private final boolean isEncoder; 15 private int pos; 16 17 public PowerPC(boolean isEncoder, int startPos) { 18 this.isEncoder = isEncoder; 19 pos = startPos; 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] & 0xFC) == 0x48 && (buf[i + 3] & 0x03) == 0x01) { 28 int src = ((buf[i] & 0x03) << 24) 29 | ((buf[i + 1] & 0xFF) << 16) 30 | ((buf[i + 2] & 0xFF) << 8) 31 | (buf[i + 3] & 0xFC); 32 33 int dest; 34 if (isEncoder) 35 dest = src + (pos + i - off); 36 else 37 dest = src - (pos + i - off); 38 39 buf[i] = (byte)(0x48 | ((dest >>> 24) & 0x03)); 40 buf[i + 1] = (byte)(dest >>> 16); 41 buf[i + 2] = (byte)(dest >>> 8); 42 buf[i + 3] = (byte)((buf[i + 3] & 0x03) | dest); 43 } 44 } 45 46 i -= off; 47 pos += i; 48 return i; 49 } 50 } 51
