397 lines
8.6 KiB
JavaScript
397 lines
8.6 KiB
JavaScript
|
var Buffer = require('buffer').Buffer;
|
||
|
|
||
|
function OffsetBuffer() {
|
||
|
this.offset = 0;
|
||
|
this.size = 0;
|
||
|
this.buffers = [];
|
||
|
}
|
||
|
module.exports = OffsetBuffer;
|
||
|
|
||
|
OffsetBuffer.prototype.isEmpty = function isEmpty() {
|
||
|
return this.size === 0;
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.clone = function clone(size) {
|
||
|
var r = new OffsetBuffer();
|
||
|
r.offset = this.offset;
|
||
|
r.size = size;
|
||
|
r.buffers = this.buffers.slice();
|
||
|
return r;
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.toChunks = function toChunks() {
|
||
|
if (this.size === 0)
|
||
|
return [];
|
||
|
|
||
|
// We are going to slice it anyway
|
||
|
if (this.offset !== 0) {
|
||
|
this.buffers[0] = this.buffers[0].slice(this.offset);
|
||
|
this.offset = 0;
|
||
|
}
|
||
|
|
||
|
var chunks = [ ];
|
||
|
var off = 0;
|
||
|
for (var i = 0; off <= this.size && i < this.buffers.length; i++) {
|
||
|
var buf = this.buffers[i];
|
||
|
off += buf.length;
|
||
|
|
||
|
// Slice off last buffer
|
||
|
if (off > this.size) {
|
||
|
buf = buf.slice(0, buf.length - (off - this.size));
|
||
|
this.buffers[i] = buf;
|
||
|
}
|
||
|
|
||
|
chunks.push(buf);
|
||
|
}
|
||
|
|
||
|
// If some buffers were skipped - trim length
|
||
|
if (i < this.buffers.length)
|
||
|
this.buffers.length = i;
|
||
|
|
||
|
return chunks;
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.toString = function toString(enc) {
|
||
|
return this.toChunks().map(function(c) {
|
||
|
return c.toString(enc);
|
||
|
}).join('');
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.use = function use(buf, off, n) {
|
||
|
this.buffers = [ buf ];
|
||
|
this.offset = off;
|
||
|
this.size = n;
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.push = function push(data) {
|
||
|
// Ignore empty writes
|
||
|
if (data.length === 0)
|
||
|
return;
|
||
|
|
||
|
this.size += data.length;
|
||
|
this.buffers.push(data);
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.has = function has(n) {
|
||
|
return this.size >= n;
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.skip = function skip(n) {
|
||
|
if (this.size === 0)
|
||
|
return;
|
||
|
|
||
|
this.size -= n;
|
||
|
|
||
|
// Fast case, skip bytes in a first buffer
|
||
|
if (this.offset + n < this.buffers[0].length) {
|
||
|
this.offset += n;
|
||
|
return;
|
||
|
}
|
||
|
|
||
|
var left = n - (this.buffers[0].length - this.offset);
|
||
|
this.offset = 0;
|
||
|
|
||
|
for (var shift = 1; left > 0 && shift < this.buffers.length; shift++) {
|
||
|
var buf = this.buffers[shift];
|
||
|
if (buf.length > left) {
|
||
|
this.offset = left;
|
||
|
break;
|
||
|
}
|
||
|
left -= buf.length;
|
||
|
}
|
||
|
this.buffers = this.buffers.slice(shift);
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.copy = function copy(target, targetOff, off, n) {
|
||
|
if (this.size === 0)
|
||
|
return;
|
||
|
if (off !== 0)
|
||
|
throw new Error('Unsupported offset in .copy()');
|
||
|
|
||
|
var toff = targetOff;
|
||
|
var first = this.buffers[0];
|
||
|
var toCopy = Math.min(n, first.length - this.offset);
|
||
|
first.copy(target, toff, this.offset, this.offset + toCopy);
|
||
|
|
||
|
toff += toCopy;
|
||
|
var left = n - toCopy;
|
||
|
for (var i = 1; left > 0 && i < this.buffers.length; i++) {
|
||
|
var buf = this.buffers[i];
|
||
|
var toCopy = Math.min(left, buf.length);
|
||
|
|
||
|
buf.copy(target, toff, 0, toCopy);
|
||
|
|
||
|
toff += toCopy;
|
||
|
left -= toCopy;
|
||
|
}
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.take = function take(n) {
|
||
|
if (n === 0)
|
||
|
return new Buffer(0);
|
||
|
|
||
|
this.size -= n;
|
||
|
|
||
|
// Fast cases
|
||
|
var first = this.buffers[0].length - this.offset;
|
||
|
if (first === n) {
|
||
|
var r = this.buffers.shift();
|
||
|
if (this.offset !== 0) {
|
||
|
r = r.slice(this.offset);
|
||
|
this.offset = 0;
|
||
|
}
|
||
|
return r;
|
||
|
} else if (first > n) {
|
||
|
var r = this.buffers[0].slice(this.offset, this.offset + n);
|
||
|
this.offset += n;
|
||
|
return r;
|
||
|
}
|
||
|
|
||
|
// Allocate and fill buffer
|
||
|
var out = new Buffer(n);
|
||
|
var toOff = 0;
|
||
|
var startOff = this.offset;
|
||
|
for (var i = 0; toOff !== n && i < this.buffers.length; i++) {
|
||
|
var buf = this.buffers[i];
|
||
|
var toCopy = Math.min(buf.length - startOff, n - toOff);
|
||
|
|
||
|
buf.copy(out, toOff, startOff, startOff + toCopy);
|
||
|
if (startOff + toCopy < buf.length) {
|
||
|
this.offset = startOff + toCopy;
|
||
|
break;
|
||
|
} else {
|
||
|
toOff += toCopy;
|
||
|
startOff = 0;
|
||
|
}
|
||
|
}
|
||
|
|
||
|
this.buffers = this.buffers.slice(i);
|
||
|
if (this.buffers.length === 0)
|
||
|
this.offset = 0;
|
||
|
|
||
|
return out;
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.peekUInt8 = function peekUInt8() {
|
||
|
return this.buffers[0][this.offset];
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readUInt8 = function readUInt8() {
|
||
|
this.size -= 1;
|
||
|
var first = this.buffers[0];
|
||
|
var r = first[this.offset];
|
||
|
if (++this.offset === first.length) {
|
||
|
this.offset = 0;
|
||
|
this.buffers.shift();
|
||
|
}
|
||
|
|
||
|
return r;
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readUInt16LE = function readUInt16LE() {
|
||
|
var first = this.buffers[0];
|
||
|
this.size -= 2;
|
||
|
|
||
|
var r;
|
||
|
var shift;
|
||
|
|
||
|
// Fast case - first buffer has all bytes
|
||
|
if (first.length - this.offset >= 2) {
|
||
|
r = first.readUInt16LE(this.offset);
|
||
|
shift = 0;
|
||
|
this.offset += 2;
|
||
|
|
||
|
// One byte here - one byte there
|
||
|
} else {
|
||
|
r = first[this.offset] | (this.buffers[1][0] << 8);
|
||
|
shift = 1;
|
||
|
this.offset = 1;
|
||
|
}
|
||
|
|
||
|
if (this.offset === this.buffers[shift].length) {
|
||
|
this.offset = 0;
|
||
|
shift++;
|
||
|
}
|
||
|
if (shift !== 0)
|
||
|
this.buffers = this.buffers.slice(shift);
|
||
|
|
||
|
return r;
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readUInt24LE = function readUInt24LE() {
|
||
|
var first = this.buffers[0];
|
||
|
|
||
|
var r;
|
||
|
var shift;
|
||
|
var firstHas = first.length - this.offset;
|
||
|
|
||
|
// Fast case - first buffer has all bytes
|
||
|
if (firstHas >= 3) {
|
||
|
r = first.readUInt16LE(this.offset) | (first[this.offset + 2] << 16);
|
||
|
shift = 0;
|
||
|
this.offset += 3;
|
||
|
|
||
|
// First buffer has 2 of 3 bytes
|
||
|
} else if (firstHas >= 2) {
|
||
|
r = first.readUInt16LE(this.offset) | (this.buffers[1][0] << 16);
|
||
|
shift = 1;
|
||
|
this.offset = 1;
|
||
|
|
||
|
// Slow case: First buffer has 1 of 3 bytes
|
||
|
} else {
|
||
|
r = first[this.offset];
|
||
|
this.offset = 0;
|
||
|
this.buffers.shift();
|
||
|
this.size -= 1;
|
||
|
|
||
|
r |= this.readUInt16LE() << 8;
|
||
|
return r;
|
||
|
}
|
||
|
|
||
|
this.size -= 3;
|
||
|
if (this.offset === this.buffers[shift].length) {
|
||
|
this.offset = 0;
|
||
|
shift++;
|
||
|
}
|
||
|
if (shift !== 0)
|
||
|
this.buffers = this.buffers.slice(shift);
|
||
|
|
||
|
return r;
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readUInt32LE = function readUInt32LE() {
|
||
|
var first = this.buffers[0];
|
||
|
|
||
|
var r;
|
||
|
var shift;
|
||
|
var firstHas = first.length - this.offset;
|
||
|
|
||
|
// Fast case - first buffer has all bytes
|
||
|
if (firstHas >= 4) {
|
||
|
r = first.readUInt32LE(this.offset);
|
||
|
shift = 0;
|
||
|
this.offset += 4;
|
||
|
|
||
|
// First buffer has 3 of 4 bytes
|
||
|
} else if (firstHas >= 3) {
|
||
|
r = (first.readUInt16LE(this.offset) |
|
||
|
(first[this.offset + 2] << 16)) +
|
||
|
(this.buffers[1][0] * 0x1000000);
|
||
|
shift = 1;
|
||
|
this.offset = 1;
|
||
|
|
||
|
// Slow case: First buffer has 2 of 4 bytes
|
||
|
} else if (firstHas >= 2) {
|
||
|
r = first.readUInt16LE(this.offset);
|
||
|
this.offset = 0;
|
||
|
this.buffers.shift();
|
||
|
this.size -= 2;
|
||
|
|
||
|
r += this.readUInt16LE() * 0x10000;
|
||
|
return r;
|
||
|
|
||
|
// Slow case: First buffer has 1 of 4 bytes
|
||
|
} else {
|
||
|
r = first[this.offset];
|
||
|
this.offset = 0;
|
||
|
this.buffers.shift();
|
||
|
this.size -= 1;
|
||
|
|
||
|
r += this.readUInt24LE() * 0x100;
|
||
|
return r;
|
||
|
}
|
||
|
|
||
|
this.size -= 4;
|
||
|
if (this.offset === this.buffers[shift].length) {
|
||
|
this.offset = 0;
|
||
|
shift++;
|
||
|
}
|
||
|
if (shift !== 0)
|
||
|
this.buffers = this.buffers.slice(shift);
|
||
|
|
||
|
return r;
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readUInt16BE = function readUInt16BE() {
|
||
|
var r = this.readUInt16LE();
|
||
|
|
||
|
return ((r & 0xff) << 8) | (r >> 8);
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readUInt24BE = function readUInt24BE() {
|
||
|
var r = this.readUInt24LE();
|
||
|
|
||
|
return ((r & 0xff) << 16) | (((r >> 8) & 0xff) << 8) | (r >> 16);
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readUInt32BE = function readUInt32BE() {
|
||
|
var r = this.readUInt32LE();
|
||
|
|
||
|
return (((r & 0xff) << 24) |
|
||
|
(((r >>> 8) & 0xff) << 16) |
|
||
|
(((r >>> 16) & 0xff) << 8) |
|
||
|
(r >>> 24)) >>> 0;
|
||
|
};
|
||
|
|
||
|
// Signed number APIs
|
||
|
|
||
|
function signedInt8(num) {
|
||
|
if (num >= 0x80)
|
||
|
return -(0xff ^ num) - 1;
|
||
|
else
|
||
|
return num;
|
||
|
}
|
||
|
|
||
|
OffsetBuffer.prototype.peekInt8 = function peekInt8() {
|
||
|
return signedInt8(this.peekUInt8());
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readInt8 = function readInt8() {
|
||
|
return signedInt8(this.readUInt8());
|
||
|
};
|
||
|
|
||
|
function signedInt16(num) {
|
||
|
if (num >= 0x8000)
|
||
|
return -(0xffff ^ num) - 1;
|
||
|
else
|
||
|
return num;
|
||
|
}
|
||
|
|
||
|
OffsetBuffer.prototype.readInt16BE = function readInt16BE() {
|
||
|
return signedInt16(this.readUInt16BE());
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readInt16LE = function readInt16LE() {
|
||
|
return signedInt16(this.readUInt16LE());
|
||
|
};
|
||
|
|
||
|
function signedInt24(num) {
|
||
|
if (num >= 0x800000)
|
||
|
return -(0xffffff ^ num) - 1;
|
||
|
else
|
||
|
return num;
|
||
|
}
|
||
|
|
||
|
OffsetBuffer.prototype.readInt24BE = function readInt24BE() {
|
||
|
return signedInt24(this.readUInt24BE());
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readInt24LE = function readInt24LE() {
|
||
|
return signedInt24(this.readUInt24LE());
|
||
|
};
|
||
|
|
||
|
function signedInt32(num) {
|
||
|
if (num >= 0x80000000)
|
||
|
return -(0xffffffff ^ num) - 1;
|
||
|
else
|
||
|
return num;
|
||
|
}
|
||
|
|
||
|
OffsetBuffer.prototype.readInt32BE = function readInt32BE() {
|
||
|
return signedInt32(this.readUInt32BE());
|
||
|
};
|
||
|
|
||
|
OffsetBuffer.prototype.readInt32LE = function readInt32LE() {
|
||
|
return signedInt32(this.readUInt32LE());
|
||
|
};
|