Or the packed-binary package on PLaneT ( http://planet.racket-lang.org/display.ss?package=packed-binary.plt&owner=williams) that is useful for reading binary formatted files. From the package description:
Performs conversions between Racket values and C structs represented as byte strings. It also provides read and write routines to perform these conversions directly to/from binary files. It uses format strings as compact descriptions of the layout of the C structs and the intended conversion to/from Racket values. This can be used in handling binary data stored in files or from network connections, among other sources. Doug On Tue, Oct 11, 2011 at 8:46 AM, Tony Garnock-Jones <to...@ccs.neu.edu>wrote: > Hi Nicolas, > > On 2011-10-08 12:41 PM, nicolas.o...@gmail.com wrote: > > I am trying to write a small implementation of Protocol Buffers > > ( http://code.google.com/p/protobuf/ ) and I have difficulties > > with bit manipulations, especially to transform a negative integer into > > a series of bytes and back. > > You might also be interested to try out (require (planet > tonyg/bitsyntax)). The documentation is at > > http://planet.racket-lang.org/package-source/tonyg/bitsyntax.plt/3/2/planet-docs/manual/index.html > > If, for example, you wanted to parse a little-endian 32-bit length > prefixed blob from a packet, you might write > > (bit-string-case packet > ([ (len :: little-endian integer bits 32) > (body :: binary bytes len) ] > body)) > > The library supports arbitrary-width integers, and 32- or 64-bit floats. > It uses the primitives that Matthew mentioned internally. > > Regards, > Tony > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users >
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