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Diffstat (limited to 'bitstring.3')
| -rw-r--r-- | bitstring.3 | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/bitstring.3 b/bitstring.3 new file mode 100644 index 0000000..efe9ae3 --- /dev/null +++ b/bitstring.3 @@ -0,0 +1,168 @@ +.\" Copyright (c) 1989 The Regents of the University of California. +.\" All rights reserved. +.\" +.\" This code is derived from software contributed to Berkeley by +.\" Paul Vixie. +.\" +.\" Redistribution and use in source and binary forms are permitted +.\" provided that the above copyright notice and this paragraph are +.\" duplicated in all such forms and that any documentation, +.\" advertising materials, and other materials related to such +.\" distribution and use acknowledge that the software was developed +.\" by the University of California, Berkeley. The name of the +.\" University may not be used to endorse or promote products derived +.\" from this software without specific prior written permission. +.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED +.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. +.\" +.\" @(#)bitstring.3 5.1 (Berkeley) 12/13/89 +.\" +.TH BITSTRING 3 "December 13, 1989" +.UC 4 +.SH NAME +bit_alloc, bit_clear, bit_decl, bit_ffs, bit_nclear, bit_nset, +bit_set, bitstr_size, bit_test \- bit-string manipulation macros +.SH SYNOPSIS +.ft B +.nf +#include <bitstring.h> + +name = bit_alloc(nbits) +bitstr_t *name; +int nbits; + +bit_decl(name, nbits) +bitstr_t name; +int nbits; + +bit_clear(name, bit) +bitstr_t name; +int bit; + +bit_ffc(name, nbits, value) +bitstr_t name; +int nbits, *value; + +bit_ffs(name, nbits, value) +bitstr_t name; +int nbits, *value; + +bit_nclear(name, start, stop) +bitstr_t name; +int start, stop; + +bit_nset(name, start, stop) +bitstr_t name; +int start, stop; + +bit_set(name, bit) +bitstr_t name; +int bit; + +bitstr_size(nbits) +int nbits; + +bit_test(name, bit) +bitstr_t name; +int bit; +.fi +.ft R +.SH DESCRIPTION +These macros operate on strings of bits. +.PP +.I Bit_alloc +returns a pointer of type +.I bitstr_t\ * +to sufficient space to store +.I nbits +bits, or NULL if no space is available. +.PP +.I Bit_decl +is a macro for allocating sufficient space to store +.I nbits +bits on the stack. +.PP +.I Bitstr_size +returns the number of elements of type +.I bitstr_t +necessary to store +.I nbits +bits. +This is useful for copying bit strings. +.PP +.I Bit_clear +and +.I bit_set +clear or set the zero-based numbered bit +.IR bit , +in the bit string +.IR name . +.PP +.I Bit_nset +and +.I bit_nclear +set or clear the zero-based numbered bits from +.I start +to +.I stop +in the bit string +.IR name . +.PP +.I Bit_test +evaluates to zero if the zero-based numbered bit +.I bit +of bit string +.I name +is set, and non-zero otherwise. +.PP +.I Bit_ffs +sets +.I *value +to the zero-based number of the first bit set in the array of +.I nbits +bits referenced by +.IR name . +If no bits are set, +.I *value +is set to -1. +.PP +.I Bit_ffc +sets +.I *value +to the zero-based number of the first bit not set in the array of +.I nbits +bits referenced by +.IR name . +If all bits are set, +.I value +is set to -1. +.SH EXAMPLE +.nf +.in +5 +#include <limits.h> +#include <bitstring.h> + +... +#define LPR_BUSY_BIT 0 +#define LPR_FORMAT_BIT 1 +#define LPR_DOWNLOAD_BIT 2 +... +#define LPR_AVAILABLE_BIT 9 +#define LPR_MAX_BITS 10 + +make_lpr_available() +{ + bitstr_t bit_decl(bitlist, LPR_MAX_BITS); + ... + bit_nclear(bitlist, 0, LPR_MAX_BITS - 1); + ... + if (!bit_test(bitlist, LPR_BUSY_BIT)) { + bit_clear(bitlist, LPR_FORMAT_BIT); + bit_clear(bitlist, LPR_DOWNLOAD_BIT); + bit_set(bitlist, LPR_AVAILABLE_BIT); + } +} +.fi +.SH "SEE ALSO" +malloc(3) |