Subject: Re: Q: How to write binary data to a file? From: Erik Naggum <firstname.lastname@example.org> Date: 03 Sep 2002 20:31:42 +0000 Newsgroups: comp.lang.lisp Message-ID: <email@example.com> * Ryan M. Rifkin | I'm a (relative) Lisp newbie, trying to learn. I'm interested in writing | integers to a file as 16-bit signed integers. (The integers I need to write | will fit in this representation. I am writing audio data to the file, which | is why I need to output in a binary format). Just specify `:element-type ' (signed-byte 16)´ and go ahead and `write-byte´ values in the appropriate range to the stream. | I'm aware of the function write-byte, but I'm not sure how to write my | signed integers. `write-byte´ does not write IBMese 8-bit bytes, but real bytes, contiguous sequences of bits in an integer. In the words of the Common Lisp Glossary: byte n. 1. adjacent bits within an integer. (The specific number of bits can vary from point to point in the program; see the function `byte´.) 2. an integer in a specified range. (The specific range can vary from point to point in the program; see the functions `open´ and `write-byte´.) This definition of "byte" predates the IBM abuse of the term and comes from the PDP-6 and -10 hardware designs, which were 36-bit word machines, meaning the smallest addressable unit was one machine word of 36 bits. I believe IBM invented the byte-addressable hardware. Your main confusion comes from thinking that "byte" means the same thing in Common Lisp as it means in, say, C. -- Erik Naggum, Oslo, Norway Act from reason, and failure makes you rethink and study harder. Act from faith, and failure makes you blame someone and push harder.