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	/*
	* Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package com.sun.java.util.jar.pack;

	import java.io.ByteArrayOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.OutputStream;
	import java.util.Arrays;
	import java.util.HashSet;
	import java.util.Set;
	import static com.sun.java.util.jar.pack.Constants.*;

	/**
	* Population-based coding.
	* See the section "Encodings of Uncorrelated Values" in the Pack200 spec.
	* @author John Rose
	*/
	// This tactic alone reduces the final zipped rt.jar by about a percent.
	class PopulationCoding implements CodingMethod {
	Histogram vHist; // histogram of all values
	int[] fValues; // list of favored values
	int fVlen; // inclusive max index
	long[] symtab; // int map of favored value -> token [1..#fValues]

	CodingMethod favoredCoding;
	CodingMethod tokenCoding;
	CodingMethod unfavoredCoding;

	int L = -1; //preferred L value for tokenCoding

	public void setFavoredValues(int[] fValues, int fVlen) {
	// Note: {f} is allFavoredValues[1..fvlen], not [0..fvlen-1].
	// This is because zero is an exceptional favored value index.
	assert(fValues[0] == 0); // must be empty
	assert(this.fValues == null); // do not do this twice
	this.fValues = fValues;
	this.fVlen = fVlen;
	if (L >= 0) {
	setL(L); // reassert
	}
	}
	public void setFavoredValues(int[] fValues) {
	int lfVlen = fValues.length-1;
	setFavoredValues(fValues, lfVlen);
	}
	public void setHistogram(Histogram vHist) {
	this.vHist = vHist;
	}
	public void setL(int L) {
	this.L = L;
	if (L >= 0 && fValues != null && tokenCoding == null) {
	tokenCoding = fitTokenCoding(fVlen, L);
	assert(tokenCoding != null);
	}
	}

	public static Coding fitTokenCoding(int fVlen, int L) {
	// Find the smallest B s.t. (B,H,0) covers fVlen.
	if (fVlen < 256)
	// H/L do not matter when B==1
	return BandStructure.BYTE1;
	Coding longest = BandStructure.UNSIGNED5.setL(L);
	if (!longest.canRepresentUnsigned(fVlen))
	return null; // failure; L is too sharp and fVlen too large
	Coding tc = longest;
	for (Coding shorter = longest; ; ) {
	shorter = shorter.setB(shorter.B()-1);
	if (shorter.umax() < fVlen)
	break;
	tc = shorter; // shorten it by reducing B
	}
	return tc;
	}

	public void setFavoredCoding(CodingMethod favoredCoding) {
	this.favoredCoding = favoredCoding;
	}
	public void setTokenCoding(CodingMethod tokenCoding) {
	this.tokenCoding = tokenCoding;
	this.L = -1;
	if (tokenCoding instanceof Coding && fValues != null) {
	Coding tc = (Coding) tokenCoding;
	if (tc == fitTokenCoding(fVlen, tc.L()))
	this.L = tc.L();
	// Otherwise, it's a non-default coding.
	}
	}
	public void setUnfavoredCoding(CodingMethod unfavoredCoding) {
	this.unfavoredCoding = unfavoredCoding;
	}

	public int favoredValueMaxLength() {
	if (L == 0)
	return Integer.MAX_VALUE;
	else
	return BandStructure.UNSIGNED5.setL(L).umax();
	}

	public void resortFavoredValues() {
	Coding tc = (Coding) tokenCoding;
	// Make a local copy before reordering.
	fValues = BandStructure.realloc(fValues, 1+fVlen);
	// Resort favoredValues within each byte-size cadre.
	int fillp = 1; // skip initial zero
	for (int n = 1; n <= tc.B(); n++) {
	int nmax = tc.byteMax(n);
	if (nmax > fVlen)
	nmax = fVlen;
	if (nmax < tc.byteMin(n))
	break;
	int low = fillp;
	int high = nmax+1;
	if (high == low) continue;
	assert(high > low)
	: high+"!>"+low;
	assert(tc.getLength(low) == n)
	: n+" != len("+(low)+") == "+
	tc.getLength(low);
	assert(tc.getLength(high-1) == n)
	: n+" != len("+(high-1)+") == "+
	tc.getLength(high-1);
	int midTarget = low + (high-low)/2;
	int mid = low;
	// Divide the values into cadres, and sort within each.
	int prevCount = -1;
	int prevLimit = low;
	for (int i = low; i < high; i++) {
	int val = fValues[i];
	int count = vHist.getFrequency(val);
	if (prevCount != count) {
	if (n == 1) {
	// For the single-byte encoding, keep strict order
	// among frequency groups.
	Arrays.sort(fValues, prevLimit, i);
	} else if (Math.abs(mid - midTarget) >
	Math.abs(i - midTarget)) {
	// Find a single inflection point
	// close to the middle of the byte-size cadre.
	mid = i;
	}
	prevCount = count;
	prevLimit = i;
	}
	}
	if (n == 1) {
	Arrays.sort(fValues, prevLimit, high);
	} else {
	// Sort up to the midpoint, if any.
	Arrays.sort(fValues, low, mid);
	Arrays.sort(fValues, mid, high);
	}
	assert(tc.getLength(low) == tc.getLength(mid));
	assert(tc.getLength(low) == tc.getLength(high-1));
	fillp = nmax+1;
	}
	assert(fillp == fValues.length);

	// Reset symtab.
	symtab = null;
	}

	public int getToken(int value) {
	if (symtab == null)
	symtab = makeSymtab();
	int pos = Arrays.binarySearch(symtab, (long)value << 32);
	if (pos < 0) pos = -pos-1;
	if (pos < symtab.length && value == (int)(symtab[pos] >>> 32))
	return (int)symtab[pos];
	else
	return 0;
	}

	public int[][] encodeValues(int[] values, int start, int end) {
	// Compute token sequence.
	int[] tokens = new int[end-start];
	int nuv = 0;
	for (int i = 0; i < tokens.length; i++) {
	int val = values[start+i];
	int tok = getToken(val);
	if (tok != 0)
	tokens[i] = tok;
	else
	nuv += 1;
	}
	// Compute unfavored value sequence.
	int[] unfavoredValues = new int[nuv];
	nuv = 0; // reset
	for (int i = 0; i < tokens.length; i++) {
	if (tokens[i] != 0) continue; // already covered
	int val = values[start+i];
	unfavoredValues[nuv++] = val;
	}
	assert(nuv == unfavoredValues.length);
	return new int[][]{ tokens, unfavoredValues };
	}

	private long[] makeSymtab() {
	long[] lsymtab = new long[fVlen];
	for (int token = 1; token <= fVlen; token++) {
	lsymtab[token-1] = ((long)fValues[token] << 32) \| token;
	}
	// Index by value:
	Arrays.sort(lsymtab);
	return lsymtab;
	}

	private Coding getTailCoding(CodingMethod c) {
	while (c instanceof AdaptiveCoding)
	c = ((AdaptiveCoding)c).tailCoding;
	return (Coding) c;
	}

	// CodingMethod methods.
	public void writeArrayTo(OutputStream out, int[] a, int start, int end) throws IOException {
	int[][] vals = encodeValues(a, start, end);
	writeSequencesTo(out, vals[0], vals[1]);
	}
	void writeSequencesTo(OutputStream out, int[] tokens, int[] uValues) throws IOException {
	favoredCoding.writeArrayTo(out, fValues, 1, 1+fVlen);
	getTailCoding(favoredCoding).writeTo(out, computeSentinelValue());
	tokenCoding.writeArrayTo(out, tokens, 0, tokens.length);
	if (uValues.length > 0)
	unfavoredCoding.writeArrayTo(out, uValues, 0, uValues.length);
	}

	int computeSentinelValue() {
	Coding fc = getTailCoding(favoredCoding);
	if (fc.isDelta()) {
	// repeat the last favored value, using delta=0
	return 0;
	} else {
	// else repeat the shorter of the min or last value
	int min = fValues[1];
	int last = min;
	// (remember that fVlen is an inclusive limit in fValues)
	for (int i = 2; i <= fVlen; i++) {
	last = fValues[i];
	min = moreCentral(min, last);
	}
	int endVal;
	if (fc.getLength(min) <= fc.getLength(last))
	return min;
	else
	return last;
	}
	}

	public void readArrayFrom(InputStream in, int[] a, int start, int end) throws IOException {
	// Parameters are fCode, L, uCode.
	setFavoredValues(readFavoredValuesFrom(in, end-start));
	// Read the tokens. Read them into the final array, for the moment.
	tokenCoding.readArrayFrom(in, a, start, end);
	// Decode the favored tokens.
	int headp = 0, tailp = -1;
	int uVlen = 0;
	for (int i = start; i < end; i++) {
	int tok = a[i];
	if (tok == 0) {
	// Make a linked list, and decode in a second pass.
	if (tailp < 0) {
	headp = i;
	} else {
	a[tailp] = i;
	}
	tailp = i;
	uVlen += 1;
	} else {
	a[i] = fValues[tok];
	}
	}
	// Walk the linked list of "zero" locations, decoding unfavored vals.
	int[] uValues = new int[uVlen];
	if (uVlen > 0)
	unfavoredCoding.readArrayFrom(in, uValues, 0, uVlen);
	for (int i = 0; i < uVlen; i++) {
	int nextp = a[headp];
	a[headp] = uValues[i];
	headp = nextp;
	}
	}

	int[] readFavoredValuesFrom(InputStream in, int maxForDebug) throws IOException {
	int[] lfValues = new int[1000]; // realloc as needed
	// The set uniqueValuesForDebug records all favored values.
	// As each new value is added, we assert that the value
	// was not already in the set.
	Set<Integer> uniqueValuesForDebug = null;
	assert((uniqueValuesForDebug = new HashSet<>()) != null);
	int fillp = 1;
	maxForDebug += fillp;
	int min = Integer.MIN_VALUE; // farthest from the center
	//int min2 = Integer.MIN_VALUE; // emulate buggy 150.7 spec.
	int last = 0;
	CodingMethod fcm = favoredCoding;
	while (fcm instanceof AdaptiveCoding) {
	AdaptiveCoding ac = (AdaptiveCoding) fcm;
	int len = ac.headLength;
	while (fillp + len > lfValues.length) {
	lfValues = BandStructure.realloc(lfValues);
	}
	int newFillp = fillp + len;
	ac.headCoding.readArrayFrom(in, lfValues, fillp, newFillp);
	while (fillp < newFillp) {
	int val = lfValues[fillp++];
	assert(uniqueValuesForDebug.add(val));
	assert(fillp <= maxForDebug);
	last = val;
	min = moreCentral(min, val);
	//min2 = moreCentral2(min2, val, min);
	}
	fcm = ac.tailCoding;
	}
	Coding fc = (Coding) fcm;
	if (fc.isDelta()) {
	for (long state = 0;;) {
	// Read a new value:
	state += fc.readFrom(in);
	int val;
	if (fc.isSubrange())
	val = fc.reduceToUnsignedRange(state);
	else
	val = (int)state;
	state = val;
	if (fillp > 1 && (val == last \|\| val == min)) //\|\| val == min2
	break;
	if (fillp == lfValues.length)
	lfValues = BandStructure.realloc(lfValues);
	lfValues[fillp++] = val;
	assert(uniqueValuesForDebug.add(val));
	assert(fillp <= maxForDebug);
	last = val;
	min = moreCentral(min, val);
	//min2 = moreCentral(min2, val);
	}
	} else {
	for (;;) {
	int val = fc.readFrom(in);
	if (fillp > 1 && (val == last \|\| val == min)) //\|\| val == min2
	break;
	if (fillp == lfValues.length)
	lfValues = BandStructure.realloc(lfValues);
	lfValues[fillp++] = val;
	assert(uniqueValuesForDebug.add(val));
	assert(fillp <= maxForDebug);
	last = val;
	min = moreCentral(min, val);
	//min2 = moreCentral2(min2, val, min);
	}
	}
	return BandStructure.realloc(lfValues, fillp);
	}

	private static int moreCentral(int x, int y) {
	int kx = (x >> 31) ^ (x << 1);
	int ky = (y >> 31) ^ (y << 1);
	// bias kx/ky to get an unsigned comparison:
	kx -= Integer.MIN_VALUE;
	ky -= Integer.MIN_VALUE;
	int xy = (kx < ky? x: y);
	// assert that this ALU-ish version is the same:
	assert(xy == moreCentralSlow(x, y));
	return xy;
	}
	// private static int moreCentral2(int x, int y, int min) {
	// // Strict implementation of buggy 150.7 specification.
	// // The bug is that the spec. says absolute-value ties are broken
	// // in favor of positive numbers, but the suggested implementation
	// // (also mentioned in the spec.) breaks ties in favor of negatives.
	// if (x + y == 0) return (x > y? x : y);
	// return min;
	// }
	private static int moreCentralSlow(int x, int y) {
	int ax = x;
	if (ax < 0) ax = -ax;
	if (ax < 0) return y; //x is MIN_VALUE
	int ay = y;
	if (ay < 0) ay = -ay;
	if (ay < 0) return x; //y is MIN_VALUE
	if (ax < ay) return x;
	if (ax > ay) return y;
	// At this point the absolute values agree, and the negative wins.
	return x < y ? x : y;
	}

	static final int[] LValuesCoded
	= { -1, 4, 8, 16, 32, 64, 128, 192, 224, 240, 248, 252 };

	public byte[] getMetaCoding(Coding dflt) {
	int K = fVlen;
	int LCoded = 0;
	if (tokenCoding instanceof Coding) {
	Coding tc = (Coding) tokenCoding;
	if (tc.B() == 1) {
	LCoded = 1;
	} else if (L >= 0) {
	assert(L == tc.L());
	for (int i = 1; i < LValuesCoded.length; i++) {
	if (LValuesCoded[i] == L) { LCoded = i; break; }
	}
	}
	}
	CodingMethod tokenDflt = null;
	if (LCoded != 0 && tokenCoding == fitTokenCoding(fVlen, L)) {
	// A simple L value is enough to recover the tokenCoding.
	tokenDflt = tokenCoding;
	}
	int FDef = (favoredCoding == dflt)?1:0;
	int UDef = (unfavoredCoding == dflt \|\| unfavoredCoding == null)?1:0;
	int TDef = (tokenCoding == tokenDflt)?1:0;
	int TDefL = (TDef == 1) ? LCoded : 0;
	assert(TDef == ((TDefL>0)?1:0));
	ByteArrayOutputStream bytes = new ByteArrayOutputStream(10);
	bytes.write(_meta_pop + FDef + 2UDef + 4TDefL);
	try {
	if (FDef == 0) bytes.write(favoredCoding.getMetaCoding(dflt));
	if (TDef == 0) bytes.write(tokenCoding.getMetaCoding(dflt));
	if (UDef == 0) bytes.write(unfavoredCoding.getMetaCoding(dflt));
	} catch (IOException ee) {
	throw new RuntimeException(ee);
	}
	return bytes.toByteArray();
	}
	public static int parseMetaCoding(byte[] bytes, int pos, Coding dflt, CodingMethod res[]) {
	int op = bytes[pos++] & 0xFF;
	if (op < _meta_pop \|\| op >= _meta_limit) return pos-1; // backup
	op -= _meta_pop;
	int FDef = op % 2;
	int UDef = (op / 2) % 2;
	int TDefL = (op / 4);
	int TDef = (TDefL > 0)?1:0;
	int L = LValuesCoded[TDefL];
	CodingMethod[] FCode = {dflt}, TCode = {null}, UCode = {dflt};
	if (FDef == 0)
	pos = BandStructure.parseMetaCoding(bytes, pos, dflt, FCode);
	if (TDef == 0)
	pos = BandStructure.parseMetaCoding(bytes, pos, dflt, TCode);
	if (UDef == 0)
	pos = BandStructure.parseMetaCoding(bytes, pos, dflt, UCode);
	PopulationCoding pop = new PopulationCoding();
	pop.L = L; // might be -1
	pop.favoredCoding = FCode[0];
	pop.tokenCoding = TCode[0]; // might be null!
	pop.unfavoredCoding = UCode[0];
	res[0] = pop;
	return pos;
	}

	private String keyString(CodingMethod m) {
	if (m instanceof Coding)
	return ((Coding)m).keyString();
	if (m == null)
	return "none";
	return m.toString();
	}
	public String toString() {
	PropMap p200 = Utils.currentPropMap();
	boolean verbose
	= (p200 != null &&
	p200.getBoolean(Utils.COM_PREFIX+"verbose.pop"));
	StringBuilder res = new StringBuilder(100);
	res.append("pop(").append("fVlen=").append(fVlen);
	if (verbose && fValues != null) {
	res.append(" fV=[");
	for (int i = 1; i <= fVlen; i++) {
	res.append(i==1?"":",").append(fValues[i]);
	}
	res.append(";").append(computeSentinelValue());
	res.append("]");
	}
	res.append(" fc=").append(keyString(favoredCoding));
	res.append(" tc=").append(keyString(tokenCoding));
	res.append(" uc=").append(keyString(unfavoredCoding));
	res.append(")");
	return res.toString();
	}
	}

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