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Length: 2632 (0xa48)
Types: TextFile
Names: »bitio.h++«
└─⟦a0efdde77⟧ Bits:30001252 EUUGD11 Tape, 1987 Spring Conference Helsinki
└─⟦this⟧ »EUUGD11/euug-87hel/sec1/image/varc++/bitio.h++«
/* file: bitio.h */
/* BFILE: include file for bit stream I/O. */
/* Bitio provides the capabilities to access unix files as arbitrary */
/* bit streams. I/O is buffered on both reading and writing. */
/* Read, write, and read/write access is defined. */
/* Bit streams of upto the width in bits of a long integer may be read */
/* and written with each access. */
/* CPU word and character boundaries are otherwise ignored. */
/* These routines are compatible with normal unix file access. */
/* Copyright (c) 1982,
W. S. Havens,
Laboratory for Computational Vision,
University of British Columbia
*/
/* Modifications:
original: WSH 82/5/20
added delayed filling of cache: WSH 82/5/27
change block size: SJK 84/5/4
*/
#define BBLKSZE 4096 /* # of bytes in bit cache */
#define R 0 /* mode = read */
#define W 1 /* mode = write */
#define RW 2 /* mode = read/write */
#define UBXBYTE 8 /* # of bits per byte */
#define WRDSZE UBXBYTE*sizeof(long)/* # of bits per long word */
#define BEOF 001
#define BRDERR 002
#define BWRERR 004
#define BSKERR 010
#define NULL 0
/* flags:
Bit Indication
--- ----------
1 EOF during last read.
2 read error occurred.
3 write error occurred.
4 seek error occurred.
*/
struct iff_bfile
{int file; /* unix file descriptor */
short wpos; /* location of bword in cache */
short bpos; /* current low-order bit */
short nwrd; /* # of bytes in cache */
short bmode; /* access mode of file */
short flags; /* EOF and ERROR flags */
char cache[BBLKSZE]; /* byte cache for stream */
};
unsigned long bseek(...);
struct iff_bfile *bopen(...), *bdopen(...);
/* Notes:
------
1) Beware of the odd bits !!
*/
/* Macros */
#define beof(bfp) ((bfp)->flags & BEOF)
#define berror(bfp) ((bfp)->flags & (BRDERR | BWRERR | BSKERR))
#define bget(bfp,n,signed) \
((n)!=8 || (bfp)->bpos || (bfp)->wpos>=(bfp)->nwrd || (bfp)->bmode==W ?\
fbget(bfp,n,signed) : \
(signed) ? \
*(char *)((bfp)->cache+((bfp)->wpos++)) : \
*(unsigned char *)((bfp)->cache+((bfp)->wpos++)) )
#define bput(bfp,bits,n) \
((n)!=8 || (bfp)->bpos || (bfp)->wpos>=BBLKSZE || (bfp)->bmode!=W ? \
fbput(bfp,bits,n) : \
(*(char *)(bfp->cache+bfp->wpos++) = bits))
/* end of file: bitio.h */
/*
Copyright (C) 1986, David Sher in the University of Rochester
Permission is granted to any individual or institution to use, copy, or
redistribute this software so long as it is not sold for profit, provided
this copyright notice is retained.
*/