-## Buffers
+# Buffer
+
+ Stability: 3 - Stable
Pure Javascript is Unicode friendly but not nice to binary data. When
dealing with TCP streams or the file system, it's necessary to handle octet
to an array of integers but corresponds to a raw memory allocation outside
the V8 heap. A `Buffer` cannot be resized.
-The `Buffer` object is global.
+The `Buffer` class is a global, making it very rare that one would need
+to ever `require('buffer')`.
-Converting between Buffers and JavaScript string objects requires an explicit encoding
-method. Here are the different string encodings;
+Converting between Buffers and JavaScript string objects requires an explicit
+encoding method. Here are the different string encodings.
-* `'ascii'` - for 7 bit ASCII data only. This encoding method is very fast, and will
-strip the high bit if set.
-Note that this encoding converts a null character (`'\0'` or `'\u0000'`) into
-`0x20` (character code of a space). If you want to convert a null character
-into `0x00`, you should use `'utf8'`.
+* `'ascii'` - for 7 bit ASCII data only. This encoding method is very fast, and
+ will strip the high bit if set.
+ Note that this encoding converts a null character (`'\0'` or `'\u0000'`) into
+ `0x20` (character code of a space). If you want to convert a null character
+ into `0x00`, you should use `'utf8'`.
* `'utf8'` - Multi byte encoded Unicode characters. Many web pages and other document formats use UTF-8.
* `'ucs2'` - 2-bytes, little endian encoded Unicode characters. It can encode
-only BMP(Basic Multilingual Plane, U+0000 - U+FFFF).
+ only BMP(Basic Multilingual Plane, U+0000 - U+FFFF).
* `'base64'` - Base64 string encoding.
* `'binary'` - A way of encoding raw binary data into strings by using only
-the first 8 bits of each character. This encoding method is deprecated and
-should be avoided in favor of `Buffer` objects where possible. This encoding
-will be removed in future versions of Node.
+ the first 8 bits of each character. This encoding method is deprecated and
+ should be avoided in favor of `Buffer` objects where possible. This encoding
+ will be removed in future versions of Node.
* `'hex'` - Encode each byte as two hexidecimal characters.
+## Class: Buffer
+
+The Buffer class is a global type for dealing with binary data directly.
+It can be constructed in a variety of ways.
### new Buffer(size)
+* `size` Number
+
Allocates a new buffer of `size` octets.
### new Buffer(array)
+* `array` Array
+
Allocates a new buffer using an `array` of octets.
### new Buffer(str, [encoding])
+* `str` String - string to encode.
+* `encoding` String - encoding to use, Optional.
+
Allocates a new buffer containing the given `str`.
`encoding` defaults to `'utf8'`.
-### buffer.write(string, [offset], [length], [encoding])
+### buf.write(string, [offset], [length], [encoding])
+
+* `string` String - data to be written to buffer
+* `offset` Number, Optional, Default: 0
+* `length` Number, Optional
+* `encoding` String, Optional, Default: 'utf8'
Writes `string` to the buffer at `offset` using the given encoding.
`offset` defaults to `0`, `encoding` defaults to `'utf8'`. `length` is
next time `buf.write()` is called.
-### buffer.toString(encoding, [start], [end])
+### buf.toString([encoding], [start], [end])
+
+* `encoding` String, Optional, Default: 'utf8'
+* `start` Number, Optional, Default: 0
+* `end` Number, Optional
Decodes and returns a string from buffer data encoded with `encoding`
(defaults to `'utf8'`) beginning at `start` (defaults to `0`) and ending at
See `buffer.write()` example, above.
-### buffer[index]
+### buf[index]
+
+<!--type=property-->
+<!--name=[index]-->
Get and set the octet at `index`. The values refer to individual bytes,
so the legal range is between `0x00` and `0xFF` hex or `0` and `255`.
// node.js
-### Buffer.isBuffer(obj)
+### Class Method: Buffer.isBuffer(obj)
+
+* `obj` Object
+* Return: Boolean
Tests if `obj` is a `Buffer`.
-### Buffer.byteLength(string, [encoding])
+### Class Method: Buffer.byteLength(string, [encoding])
+
+* `string` String
+* `encoding` String, Optional, Default: 'utf8'
+* Return: Number
Gives the actual byte length of a string. `encoding` defaults to `'utf8'`.
This is not the same as `String.prototype.length` since that returns the
// ½ + ¼ = ¾: 9 characters, 12 bytes
+### buf.length
-### buffer.length
+* Number
The size of the buffer in bytes. Note that this is not necessarily the size
of the contents. `length` refers to the amount of memory allocated for the
// 1234
// 1234
-### buffer.copy(targetBuffer, [targetStart], [sourceStart], [sourceEnd])
+### buf.copy(targetBuffer, [targetStart], [sourceStart], [sourceEnd])
+
+* `targetBuffer` Buffer object - Buffer to copy into
+* `targetStart` Number, Optional, Default: 0
+* `sourceStart` Number, Optional, Default: 0
+* `sourceEnd` Number, Optional, Default: 0
Does copy between buffers. The source and target regions can be overlapped.
`targetStart` and `sourceStart` default to `0`.
// !!!!!!!!qrst!!!!!!!!!!!!!
-### buffer.slice([start], [end])
+### buf.slice([start], [end])
+
+* `start` Number, Optional, Default: 0
+* `end` Number, Optional, Default: 0
Returns a new buffer which references the same memory as the old, but offset
and cropped by the `start` (defaults to `0`) and `end` (defaults to
// abc
// !bc
-### buffer.readUInt8(offset, [noAssert])
+### buf.readUInt8(offset, [noAssert])
+
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
+* Return: Number
Reads an unsigned 8 bit integer from the buffer at the specified offset.
// 0x23
// 0x42
-### buffer.readUInt16LE(offset, [noAssert])
-### buffer.readUInt16BE(offset, [noAssert])
+### buf.readUInt16LE(offset, [noAssert])
+### buf.readUInt16BE(offset, [noAssert])
+
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
+* Return: Number
Reads an unsigned 16 bit integer from the buffer at the specified offset with
specified endian format.
// 0x2342
// 0x4223
-### buffer.readUInt32LE(offset, [noAssert])
-### buffer.readUInt32BE(offset, [noAssert])
+### buf.readUInt32LE(offset, [noAssert])
+### buf.readUInt32BE(offset, [noAssert])
+
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
+* Return: Number
Reads an unsigned 32 bit integer from the buffer at the specified offset with
specified endian format.
// 0x03042342
// 0x42230403
-### buffer.readInt8(offset, [noAssert])
+### buf.readInt8(offset, [noAssert])
+
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
+* Return: Number
Reads a signed 8 bit integer from the buffer at the specified offset.
Works as `buffer.readUInt8`, except buffer contents are treated as two's
complement signed values.
-### buffer.readInt16LE(offset, [noAssert])
-### buffer.readInt16BE(offset, [noAssert])
+### buf.readInt16LE(offset, [noAssert])
+### buf.readInt16BE(offset, [noAssert])
+
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
+* Return: Number
Reads a signed 16 bit integer from the buffer at the specified offset with
specified endian format.
Works as `buffer.readUInt16*`, except buffer contents are treated as two's
complement signed values.
-### buffer.readInt32LE(offset, [noAssert])
-### buffer.readInt32BE(offset, [noAssert])
+### buf.readInt32LE(offset, [noAssert])
+### buf.readInt32BE(offset, [noAssert])
+
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
+* Return: Number
Reads a signed 32 bit integer from the buffer at the specified offset with
specified endian format.
Works as `buffer.readUInt32*`, except buffer contents are treated as two's
complement signed values.
-### buffer.readFloatLE(offset, [noAssert])
-### buffer.readFloatBE(offset, [noAssert])
+### buf.readFloatLE(offset, [noAssert])
+### buf.readFloatBE(offset, [noAssert])
+
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
+* Return: Number
Reads a 32 bit float from the buffer at the specified offset with specified
endian format.
// 0x01
-### buffer.readDoubleLE(offset, [noAssert])
-### buffer.readDoubleBE(offset, [noAssert])
+### buf.readDoubleLE(offset, [noAssert])
+### buf.readDoubleBE(offset, [noAssert])
+
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
+* Return: Number
Reads a 64 bit double from the buffer at the specified offset with specified
endian format.
// 0.3333333333333333
-### buffer.writeUInt8(value, offset, [noAssert])
+### buf.writeUInt8(value, offset, [noAssert])
+
+* `value` Number
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset. Note, `value` must be a
valid unsigned 8 bit integer.
// <Buffer 03 04 23 42>
-### buffer.writeUInt16LE(value, offset, [noAssert])
-### buffer.writeUInt16BE(value, offset, [noAssert])
+### buf.writeUInt16LE(value, offset, [noAssert])
+### buf.writeUInt16BE(value, offset, [noAssert])
+
+* `value` Number
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid unsigned 16 bit integer.
// <Buffer de ad be ef>
// <Buffer ad de ef be>
-### buffer.writeUInt32LE(value, offset, [noAssert])
-### buffer.writeUInt32BE(value, offset, [noAssert])
+### buf.writeUInt32LE(value, offset, [noAssert])
+### buf.writeUInt32BE(value, offset, [noAssert])
+
+* `value` Number
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid unsigned 32 bit integer.
// <Buffer fe ed fa ce>
// <Buffer ce fa ed fe>
-### buffer.writeInt8(value, offset, [noAssert])
+### buf.writeInt8(value, offset, [noAssert])
+
+* `value` Number
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset. Note, `value` must be a
valid signed 8 bit integer.
Works as `buffer.writeUInt8`, except value is written out as a two's complement
signed integer into `buffer`.
-### buffer.writeInt16LE(value, offset, [noAssert])
-### buffer.writeInt16BE(value, offset, [noAssert])
+### buf.writeInt16LE(value, offset, [noAssert])
+### buf.writeInt16BE(value, offset, [noAssert])
+
+* `value` Number
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid signed 16 bit integer.
Works as `buffer.writeUInt16*`, except value is written out as a two's
complement signed integer into `buffer`.
-### buffer.writeInt32LE(value, offset, [noAssert])
-### buffer.writeInt32BE(value, offset, [noAssert])
+### buf.writeInt32LE(value, offset, [noAssert])
+### buf.writeInt32BE(value, offset, [noAssert])
+
+* `value` Number
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid signed 32 bit integer.
Works as `buffer.writeUInt32*`, except value is written out as a two's
complement signed integer into `buffer`.
-### buffer.writeFloatLE(value, offset, [noAssert])
-### buffer.writeFloatBE(value, offset, [noAssert])
+### buf.writeFloatLE(value, offset, [noAssert])
+### buf.writeFloatBE(value, offset, [noAssert])
+
+* `value` Number
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid 32 bit float.
// <Buffer 4f 4a fe bb>
// <Buffer bb fe 4a 4f>
-### buffer.writeDoubleLE(value, offset, [noAssert])
-### buffer.writeDoubleBE(value, offset, [noAssert])
+### buf.writeDoubleLE(value, offset, [noAssert])
+### buf.writeDoubleBE(value, offset, [noAssert])
+
+* `value` Number
+* `offset` Number
+* `noAssert` Boolean, Optional, Default: false
Writes `value` to the buffer at the specified offset with specified endian
format. Note, `value` must be a valid 64 bit double.
// <Buffer 43 eb d5 b7 dd f9 5f d7>
// <Buffer d7 5f f9 dd b7 d5 eb 43>
-### buffer.fill(value, [offset], [end])
+### buf.fill(value, [offset], [end])
+
+* `value`
+* `offset` Number, Optional
+* `end` Number, Optional
Fills the buffer with the specified value. If the `offset` (defaults to `0`)
and `end` (defaults to `buffer.length`) are not given it will fill the entire
var b = new Buffer(50);
b.fill("h");
-### INSPECT_MAX_BYTES
+## buffer.INSPECT_MAX_BYTES
+
+* Number, Default: 50
How many bytes will be returned when `buffer.inspect()` is called. This can
be overridden by user modules.
+
+Note that this is a property on the buffer module returned by
+`require('buffer')`, not on the Buffer global, or a buffer instance.
+
+## Class: SlowBuffer
+
+This class is primarily for internal use. JavaScript programs should
+use Buffer instead of using SlowBuffer.
+
+In order to avoid the overhead of allocating many C++ Buffer objects for
+small blocks of memory in the lifetime of a server, Node allocates memory
+in 8Kb (8192 byte) chunks. If a buffer is smaller than this size, then it
+will be backed by a parent SlowBuffer object. If it is larger than this,
+then Node will allocate a SlowBuffer slab for it directly.
projects / platform / upstream / nodejs.git / commitdiff