提交 f7851cc3 authored 作者: Thomas Mueller Graf's avatar Thomas Mueller Graf

ArchiveTool: slightly improved compression

上级 c352afd0
......@@ -614,6 +614,102 @@ public class ArchiveTool {
* Get the sort key and length of a chunk.
*/
private static int[] getKey(byte[] data, int start, int maxPos) {
int minLen = 4 * 1024;
int mask = 4 * 1024 - 1;
long min = Long.MAX_VALUE;
int pos = start;
for (int j = 0; pos < maxPos; pos++, j++) {
if (pos <= start + 10) {
continue;
}
long hash = getSipHash24(data, pos - 10, pos, 111, 11224);
if (hash < min) {
min = hash;
}
if (j > minLen) {
if ((hash & mask) == 1) {
break;
}
if (j > minLen * 4 && (hash & (mask >> 1)) == 1) {
break;
}
if (j > minLen * 16) {
break;
}
}
}
int len = pos - start;
int[] counts = new int[8];
for (int i = start; i < pos; i++) {
int x = data[i] & 0xff;
counts[x >> 5]++;
}
int cs = 0;
for (int i = 0; i < 8; i++) {
cs *= 2;
if (counts[i] > (len / 32)) {
cs += 1;
}
}
int[] key = new int[4];
; // TODO test if cs makes a difference
key[0] = (int) (min >>> 32);
key[1] = (int) min;
key[2] = cs;
key[3] = len;
return key;
}
public static long getSipHash24(byte[] b, int start, int end, long k0,
long k1) {
long v0 = k0 ^ 0x736f6d6570736575L;
long v1 = k1 ^ 0x646f72616e646f6dL;
long v2 = k0 ^ 0x6c7967656e657261L;
long v3 = k1 ^ 0x7465646279746573L;
int repeat;
for (int off = start; off <= end + 8; off += 8) {
long m;
if (off <= end) {
m = 0;
int i = 0;
for (; i < 8 && off + i < end; i++) {
m |= ((long) b[off + i] & 255) << (8 * i);
}
if (i < 8) {
m |= ((long) end - start) << 56;
}
v3 ^= m;
repeat = 2;
} else {
m = 0;
v2 ^= 0xff;
repeat = 4;
}
for (int i = 0; i < repeat; i++) {
v0 += v1;
v2 += v3;
v1 = Long.rotateLeft(v1, 13);
v3 = Long.rotateLeft(v3, 16);
v1 ^= v0;
v3 ^= v2;
v0 = Long.rotateLeft(v0, 32);
v2 += v1;
v0 += v3;
v1 = Long.rotateLeft(v1, 17);
v3 = Long.rotateLeft(v3, 21);
v1 ^= v2;
v3 ^= v0;
v2 = Long.rotateLeft(v2, 32);
}
v0 ^= m;
}
return v0 ^ v1 ^ v2 ^ v3;
}
/**
* Get the sort key and length of a chunk.
*/
private static int[] getKeyOld(byte[] data, int start, int maxPos) {
int minLen = 4 * 1024;
int mask = 4 * 1024 - 1;
int min = Integer.MAX_VALUE;
......
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