single-channel-simple-stream

This class has a single octet buffer and allows read-modify-write operations. File streams are single-channel streams.

A single-channel stream has one buffer and a directional state to specify whether the buffer and stream is in read, write, or read-modify mode. Flushes (device-writes) are performed when switching from write or read-modify to read mode if the buffer is dirty, and may involve a call to device-file-position. single-channel-simple-streams tend to support file-position and file-length, though this is not required.

A subclass of single-channel-simple-stream, namely direct-simple-stream, allows input from or output to a buffer directly. Subclasses of direct-simple-stream allow buffers to be read form or written to, in a similar manner as string-input or string-output streams.

A subclass of file-simple-stream and of direct-simple-stream allows the opening of mapped files. Instead of a buffer, a mapped file provides a direct mapping to the file within memory. Mapping overflows are handled by device-extend instead of device-read and device-write.

This kind of stream is useful for files and other devices which must allow random write/read access.

See streams.htm for a description of the new simple-stream stream implementation.

Copyright (c) 1998-2001, Franz Inc. Berkeley, CA., USA. All rights reserved.
Documentation for Allegro CL version 6.1 update # 1. This page was not revised.
Created 2001.12.15.