Luiji Maryo <lu...@users.sourceforge.net> writes: > Hello, > > I have some questions regarding Guile I/O and byte order. If you are dealing with binary data, you should be using bytevectors and binary ports, rather than strings.
> 1. Is there an I/O function for reading a fixed set of bytes into a > buffer, i.e. if I wanted to read a 56-byte string from a binary > archive? For this, In (ice-9 binary-ports) or (rnrs io ports), there is 'get-bytevector-n!' > 2. Is there a way to specifically read a 8/16/32/64-bit string from a > file/port? For reading bytes you can use 'get-u8', and for reading multiple bytes as a bytevector 'get-bytevector-n'. (rnrs bytevectors) contains procedures for setting/getting 8/16/32/64 bit quantities. > 3. Is there a built-in function for converting between byte orders > (i.e. BSD-style htobe32 and such) or must I implement them myself? (rnrs bytevectors) has procedures for dealing with endianness, at the bytevector level. So I can, for instance, use (bytevector-u16-ref bv index (native-endianness)) to extract a 16 bit integer from a given index in a bytevector. If you wanted to specify a particular endianness, I could use (endianness big) or (endianness little). For integers you could use ntohs, ntohl, htons, htonl, but that is native endianness <-> network order only. > 4. Is writing an archive manager using Guile for implementing archive > formats a bad idea to start with? Writing in Scheme is never a bad idea. ;-) -- Ian Price "Programming is like pinball. The reward for doing it well is the opportunity to do it again" - from "The Wizardy Compiled"
