| public PeekBits ( int bitCount ) : int | ||
| bitCount | int | The number of bits to peek. |
| return | int | |
public int GetSymbol(StreamManipulator input)
{
int lookahead, symbol;
if ((lookahead = input.PeekBits(9)) >= 0) {
if ((symbol = tree[lookahead]) >= 0) {
input.DropBits(symbol & 15);
return symbol >> 4;
}
int subtree = -(symbol >> 4);
int bitlen = symbol & 15;
if ((lookahead = input.PeekBits(bitlen)) >= 0) {
symbol = tree[subtree | (lookahead >> 9)];
input.DropBits(symbol & 15);
return symbol >> 4;
} else {
int bits = input.AvailableBits;
lookahead = input.PeekBits(bits);
symbol = tree[subtree | (lookahead >> 9)];
if ((symbol & 15) <= bits) {
input.DropBits(symbol & 15);
return symbol >> 4;
} else {
return -1;
}
}
} else {
int bits = input.AvailableBits;
lookahead = input.PeekBits(bits);
symbol = tree[lookahead];
if (symbol >= 0 && (symbol & 15) <= bits) {
input.DropBits(symbol & 15);
return symbol >> 4;
} else {
return -1;
}
}
}
public bool Decode(StreamManipulator input)
{
decode_loop:
for (;;) {
switch (mode) {
case LNUM:
lnum = input.PeekBits(5);
if (lnum < 0) {
return false;
}
lnum += 257;
input.DropBits(5);
// System.err.println("LNUM: "+lnum);
mode = DNUM;
goto case DNUM; // fall through
case DNUM:
dnum = input.PeekBits(5);
if (dnum < 0) {
return false;
}
dnum++;
input.DropBits(5);
// System.err.println("DNUM: "+dnum);
num = lnum+dnum;
litdistLens = new byte[num];
mode = BLNUM;
goto case BLNUM; // fall through
case BLNUM:
blnum = input.PeekBits(4);
if (blnum < 0) {
return false;
}
blnum += 4;
input.DropBits(4);
blLens = new byte[19];
ptr = 0;
// System.err.println("BLNUM: "+blnum);
mode = BLLENS;
goto case BLLENS; // fall through
case BLLENS:
while (ptr < blnum) {
int len = input.PeekBits(3);
if (len < 0) {
return false;
}
input.DropBits(3);
// System.err.println("blLens["+BL_ORDER[ptr]+"]: "+len);
blLens[BL_ORDER[ptr]] = (byte) len;
ptr++;
}
blTree = new InflaterHuffmanTree(blLens);
blLens = null;
ptr = 0;
mode = LENS;
goto case LENS; // fall through
case LENS:
{
int symbol;
while (((symbol = blTree.GetSymbol(input)) & ~15) == 0) {
/* Normal case: symbol in [0..15] */
// System.err.println("litdistLens["+ptr+"]: "+symbol);
litdistLens[ptr++] = lastLen = (byte)symbol;
if (ptr == num) {
/* Finished */
return true;
}
}
/* need more input ? */
if (symbol < 0) {
return false;
}
/* otherwise repeat code */
if (symbol >= 17) {
/* repeat zero */
// System.err.println("repeating zero");
lastLen = 0;
} else {
if (ptr == 0) {
throw new SharpZipBaseException();
}
}
repSymbol = symbol-16;
}
mode = REPS;
goto case REPS; // fall through
case REPS:
{
int bits = repBits[repSymbol];
int count = input.PeekBits(bits);
if (count < 0) {
return false;
}
input.DropBits(bits);
count += repMin[repSymbol];
// System.err.println("litdistLens repeated: "+count);
if (ptr + count > num) {
throw new SharpZipBaseException();
}
while (count-- > 0) {
litdistLens[ptr++] = lastLen;
}
if (ptr == num) {
/* Finished */
return true;
}
}
mode = LENS;
goto decode_loop;
}
}
}
public bool Decode(StreamManipulator input)
{
decode_loop:
for (;;) {
switch (mode) {
case LNUM:
lnum = input.PeekBits(5);
if (lnum < 0) {
return false;
}
lnum += 257;
input.DropBits(5);
mode = DNUM;
goto case DNUM;
case DNUM:
dnum = input.PeekBits(5);
if (dnum < 0) {
return false;
}
dnum++;
input.DropBits(5);
num = lnum+dnum;
litdistLens = new byte[num];
mode = BLNUM;
goto case BLNUM;
case BLNUM:
blnum = input.PeekBits(4);
if (blnum < 0) {
return false;
}
blnum += 4;
input.DropBits(4);
blLens = new byte[19];
ptr = 0;
mode = BLLENS;
goto case BLLENS;
case BLLENS:
while (ptr < blnum) {
int len = input.PeekBits(3);
if (len < 0) {
return false;
}
input.DropBits(3);
blLens[BL_ORDER[ptr]] = (byte) len;
ptr++;
}
blTree = new InflaterHuffmanTree(blLens);
blLens = null;
ptr = 0;
mode = LENS;
goto case LENS;
case LENS:
{
int symbol;
while (((symbol = blTree.GetSymbol(input)) & ~15) == 0) {
litdistLens[ptr++] = lastLen = (byte)symbol;
if (ptr == num) {
return true;
}
}
if (symbol < 0) {
return false;
}
if (symbol >= 17) {
lastLen = 0;
} else {
if (ptr == 0) {
throw new SharpZipBaseException();
}
}
repSymbol = symbol-16;
}
mode = REPS;
goto case REPS;
case REPS:
{
int bits = repBits[repSymbol];
int count = input.PeekBits(bits);
if (count < 0) {
return false;
}
input.DropBits(bits);
count += repMin[repSymbol];
if (ptr + count > num) {
throw new SharpZipBaseException();
}
while (count-- > 0) {
litdistLens[ptr++] = lastLen;
}
if (ptr == num) {
return true;
}
}
mode = LENS;
goto decode_loop;
}
}
}
public bool Decode(StreamManipulator input)
{
int num2;
int num3;
Label_0000:
switch (this.mode)
{
case 0:
this.lnum = input.PeekBits(5);
if (this.lnum >= 0)
{
this.lnum += 0x101;
input.DropBits(5);
this.mode = 1;
break;
}
return false;
case 1:
break;
case 2:
goto Label_00B9;
case 3:
goto Label_013B;
case 4:
goto Label_01A8;
case 5:
goto Label_01EE;
default:
goto Label_0000;
}
this.dnum = input.PeekBits(5);
if (this.dnum < 0)
{
return false;
}
this.dnum++;
input.DropBits(5);
this.num = this.lnum + this.dnum;
this.litdistLens = new byte[this.num];
this.mode = 2;
Label_00B9:
this.blnum = input.PeekBits(4);
if (this.blnum < 0)
{
return false;
}
this.blnum += 4;
input.DropBits(4);
this.blLens = new byte[0x13];
this.ptr = 0;
this.mode = 3;
Label_013B:
while (this.ptr < this.blnum)
{
int num = input.PeekBits(3);
if (num < 0)
{
return false;
}
input.DropBits(3);
this.blLens[BL_ORDER[this.ptr]] = (byte) num;
this.ptr++;
}
this.blTree = new InflaterHuffmanTree(this.blLens);
this.blLens = null;
this.ptr = 0;
this.mode = 4;
Label_01A8:
while (((num2 = this.blTree.GetSymbol(input)) & -16) == 0)
{
this.litdistLens[this.ptr++] = this.lastLen = (byte) num2;
if (this.ptr == this.num)
{
return true;
}
}
if (num2 < 0)
{
return false;
}
if (num2 >= 0x11)
{
this.lastLen = 0;
}
else if (this.ptr == 0)
{
throw new SharpZipBaseException();
}
this.repSymbol = num2 - 0x10;
this.mode = 5;
Label_01EE:
num3 = repBits[this.repSymbol];
int num4 = input.PeekBits(num3);
if (num4 < 0)
{
return false;
}
input.DropBits(num3);
num4 += repMin[this.repSymbol];
if ((this.ptr + num4) > this.num)
{
throw new SharpZipBaseException();
}
while (num4-- > 0)
{
this.litdistLens[this.ptr++] = this.lastLen;
}
if (this.ptr == this.num)
{
return true;
}
this.mode = 4;
goto Label_0000;
}
public int GetSymbol(StreamManipulator input)
{
int num2;
int index = input.PeekBits(9);
if (index >= 0)
{
num2 = this.tree[index];
if (num2 >= 0)
{
input.DropBits(num2 & 15);
return (num2 >> 4);
}
int num3 = -(num2 >> 4);
int bitCount = num2 & 15;
index = input.PeekBits(bitCount);
if (index >= 0)
{
num2 = this.tree[num3 | (index >> 9)];
input.DropBits(num2 & 15);
return (num2 >> 4);
}
int num5 = input.AvailableBits;
index = input.PeekBits(num5);
num2 = this.tree[num3 | (index >> 9)];
if ((num2 & 15) <= num5)
{
input.DropBits(num2 & 15);
return (num2 >> 4);
}
return -1;
}
int availableBits = input.AvailableBits;
index = input.PeekBits(availableBits);
num2 = this.tree[index];
if ((num2 >= 0) && ((num2 & 15) <= availableBits))
{
input.DropBits(num2 & 15);
return (num2 >> 4);
}
return -1;
}
