10564b1175
groff 1.23.0 added .MR to its -man macro package. The NEWS file states
that the inclusion of the macro "was prompted by its introduction to
Plan 9 from User Space's troff in August 2020." From d32deab it seems
that the name for Plan 9 from User Space's implementation was suggested
by groff maintainer G. Brandon Robinson.
Not sure if the intention was to make these definitions compatible, but
it would be nice if they were.
Currently, Plan 9 from User Space's .MR expects its second argument to
be parenthesized. groff's .MR does not. This results in extra
parentheses appearing in manual references when viewing Plan 9 from User
Space's manual pages on a system using groff.
127 lines
2.1 KiB
Groff
127 lines
2.1 KiB
Groff
.TH MEMORY 3
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.SH NAME
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memccpy, memchr, memcmp, memcpy, memmove, memset \- memory operations
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.PP
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.ta \w'\fLvoid* 'u
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.B
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void* memccpy(void *s1, void *s2, int c, long n)
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.PP
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.B
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void* memchr(void *s, int c, long n)
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.PP
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.B
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int memcmp(void *s1, void *s2, long n)
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.PP
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.B
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void* memcpy(void *s1, void *s2, long n)
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.PP
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.B
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void* memmove(void *s1, void *s2, long n)
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.PP
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.B
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void* memset(void *s, int c, long n)
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.SH DESCRIPTION
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These functions operate efficiently on memory areas
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(arrays of bytes bounded by a count, not terminated by a zero byte).
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They do not check for the overflow of any receiving memory area.
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.PP
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.I Memccpy
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copies bytes from memory area
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.I s2
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into
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.IR s1 ,
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stopping after the first occurrence of byte
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.I c
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has been copied, or after
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.I n
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bytes have been copied, whichever comes first.
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It returns a pointer to the byte after
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the copy of
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.I c
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in
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.IR s1 ,
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or zero if
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.I c
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was not found in the first
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.I n
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bytes of
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.IR s2 .
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.PP
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.I Memchr
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returns a pointer to the first
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occurrence of byte
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.I c
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in the first
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.I n
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bytes of memory area
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.IR s,
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or zero if
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.I c
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does not occur.
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.PP
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.I Memcmp
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compares its arguments, looking at the first
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.I n
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bytes only, and returns an integer
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less than, equal to, or greater than 0,
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according as
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.I s1
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is lexicographically less than, equal to, or
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greater than
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.IR s2 .
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The comparison is bytewise unsigned.
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.PP
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.I Memcpy
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copies
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.I n
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bytes from memory area
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.I s2
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to
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.IR s1 .
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It returns
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.IR s1 .
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.PP
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.I Memmove
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works like
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.IR memcpy ,
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except that it is guaranteed to work if
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.I s1
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and
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.IR s2
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overlap.
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.PP
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.I Memset
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sets the first
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.I n
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bytes in memory area
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.I s
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to the value of byte
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.IR c .
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It returns
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.IR s .
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.SH SOURCE
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All these routines have portable C implementations in
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.BR \*9/src/lib9 .
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.\" Most also have machine-dependent assembly language implementations in
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.\" .BR \*9/lib9/$objtype .
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.SH SEE ALSO
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.MR strcat 3
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.SH BUGS
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ANSI C does not require
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.I memcpy
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to handle overlapping source and destination; on Plan 9, it does, so
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.I memmove
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and
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.I memcpy
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behave identically.
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.PP
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If
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.I memcpy
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and
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.I memmove
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are handed a negative count, they abort.
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