binary-pmb
v0.3.5
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Unpack multibyte binary values from buffers and streams. (Maintenance fork of substack's `binary`)
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binary-pmb
Unpack multibyte binary values from buffers and streams. (Maintenance fork of
substack's binary
)
You can specify the endianness and signedness of the fields to be unpacked too.
This module is a cleaner and more complete version of bufferlist's binary module that runs on pre-allocated buffers instead of a linked list.
Installation
npm install binary
Examples
See the docs/examples/ directory.
API
var binary = require('binary-pmb')
- var b = binary()
- binary.parse(buf)
- b.vars
- b.word{8,16,24,32,64}{l,b}{e,u,s}(key)
- b.buffer(key, size)
- b.str(key, size[, encoding])
- b.utf8(key, size)
- b.skip(dist)
- b.scan(key, buffer)
- b.tap(cb)
- b.into(key, cb)
- b.loop(cb)
- b.flush()
var b = binary()
Return a new writable stream b
that has the chainable methods documented below
for buffering binary input.
binary.parse(buf)
Parse a static buffer in one pass. Returns a chainable interface with the
methods below plus a vars
field to get at the variable stash as the
last item in a chain.
In parse mode, methods will set their keys to null
if the buffer isn't big
enough except buffer()
and scan()
which read up up to the end of the buffer
and stop.
b.vars
See binary.parse
.
b.word{8,16,24,32,64}{l,b}{e,u,s}(key)
Parse bytes in the buffer or stream given:
- number of bits
- endianness ( l : little, b : big ),
- signedness ( u and e : unsigned, s : signed )
These functions won't start parsing until all previous parser functions have run and the data is available.
The result of the parse goes into the variable stash at key
.
If key
has dots (.
s), it refers to a nested address. If parent container
values don't exist they will be created automatically, so for instance you can
assign into dst.addr
and dst.port
and the dst
key in the variable stash
will be { addr : x, port : y }
afterwards.
b.buffer(key, size)
Take size
bytes directly off the buffer stream, putting the resulting buffer
slice in the variable stash at key
.
vars lookup: If size
is a string, use the value at vars[size]
.
The key follows the same dotted address rules as the word functions.
b.str(key, size[, encoding])
Same as .buffer
but decode the data as a string.
Default encoding
is latin1
.
b.utf8(key, size)
Same as .buffer
but decode the data as a UTF-8 string.
b.skip(dist)
Jump dist
bytes ahead.
The "vars lookup" feature from .buffer
applies to dist
.
b.scan(key, buffer)
Search for buffer
in the stream and store all the intervening data in the
stash at at key
, excluding the search buffer. If buffer
passed as a string,
it will be converted into a Buffer internally.
For example, to read in a line you can just do:
var b = binary()
.scan('line', new Buffer('\r\n'))
.tap(function (vars) {
console.log(vars.line)
})
;
stream.pipe(b);
b.tap(cb)
The callback cb
is provided with the variable stash from all the previous
actions once they've all finished.
You can nest additional actions onto this
inside the callback.
b.into(key, cb)
Like .tap()
, except all nested actions will assign into a key
in the vars
stash.
b.loop(cb)
Loop, each time calling cb(end, vars)
for function end
and the variable
stash with this
set to a new chain for nested parsing. The loop terminates
once end
is called.
b.flush()
Clear the variable stash entirely.
Known issues
- The word64 functions will only return approximations since javascript uses IEEE floating point for all number types. Mind the loss of precision.
License
MIT