1 058b0118 2005-01-03 devnull .TH MEMORY 3
  2 058b0118 2005-01-03 devnull .SH NAME
  3 058b0118 2005-01-03 devnull memccpy, memchr, memcmp, memcpy, memmove, memset \- memory operations
  4 058b0118 2005-01-03 devnull .SH SYNOPSIS
  5 058b0118 2005-01-03 devnull .B #include <u.h>
  6 058b0118 2005-01-03 devnull .br
  7 058b0118 2005-01-03 devnull .B #include <libc.h>
  8 058b0118 2005-01-03 devnull .PP
  9 058b0118 2005-01-03 devnull .ta \w'\fLvoid* 'u
 10 058b0118 2005-01-03 devnull .B
 11 058b0118 2005-01-03 devnull void*	memccpy(void *s1, void *s2, int c, long n)
 12 058b0118 2005-01-03 devnull .PP
 13 058b0118 2005-01-03 devnull .B
 14 058b0118 2005-01-03 devnull void*	memchr(void *s, int c, long n)
 15 058b0118 2005-01-03 devnull .PP
 16 058b0118 2005-01-03 devnull .B
 17 058b0118 2005-01-03 devnull int	memcmp(void *s1, void *s2, long n)
 18 058b0118 2005-01-03 devnull .PP
 19 058b0118 2005-01-03 devnull .B
 20 058b0118 2005-01-03 devnull void*	memcpy(void *s1, void *s2, long n)
 21 058b0118 2005-01-03 devnull .PP
 22 058b0118 2005-01-03 devnull .B
 23 058b0118 2005-01-03 devnull void*	memmove(void *s1, void *s2, long n)
 24 058b0118 2005-01-03 devnull .PP
 25 058b0118 2005-01-03 devnull .B
 26 058b0118 2005-01-03 devnull void*	memset(void *s, int c, long n)
 27 058b0118 2005-01-03 devnull .SH DESCRIPTION
 28 058b0118 2005-01-03 devnull These functions operate efficiently on memory areas
 29 058b0118 2005-01-03 devnull (arrays of bytes bounded by a count, not terminated by a zero byte).
 30 058b0118 2005-01-03 devnull They do not check for the overflow of any receiving memory area.
 31 058b0118 2005-01-03 devnull .PP
 32 058b0118 2005-01-03 devnull .I Memccpy
 33 058b0118 2005-01-03 devnull copies bytes from memory area
 34 058b0118 2005-01-03 devnull .I s2
 35 058b0118 2005-01-03 devnull into
 36 058b0118 2005-01-03 devnull .IR s1 ,
 37 058b0118 2005-01-03 devnull stopping after the first occurrence of byte
 38 058b0118 2005-01-03 devnull .I c
 39 058b0118 2005-01-03 devnull has been copied, or after
 40 058b0118 2005-01-03 devnull .I n
 41 058b0118 2005-01-03 devnull bytes have been copied, whichever comes first.
 42 058b0118 2005-01-03 devnull It returns a pointer to the byte after
 43 058b0118 2005-01-03 devnull the copy of
 44 058b0118 2005-01-03 devnull .I c
 45 058b0118 2005-01-03 devnull in
 46 058b0118 2005-01-03 devnull .IR s1 ,
 47 058b0118 2005-01-03 devnull or zero if
 48 058b0118 2005-01-03 devnull .I c
 49 058b0118 2005-01-03 devnull was not found in the first
 50 058b0118 2005-01-03 devnull .I n
 51 058b0118 2005-01-03 devnull bytes of
 52 058b0118 2005-01-03 devnull .IR s2 .
 53 058b0118 2005-01-03 devnull .PP
 54 058b0118 2005-01-03 devnull .I Memchr
 55 058b0118 2005-01-03 devnull returns a pointer to the first
 56 058b0118 2005-01-03 devnull occurrence of byte
 57 058b0118 2005-01-03 devnull .I c
 58 058b0118 2005-01-03 devnull in the first
 59 058b0118 2005-01-03 devnull .I n
 60 058b0118 2005-01-03 devnull bytes of memory area
 61 058b0118 2005-01-03 devnull .IR s,
 62 058b0118 2005-01-03 devnull or zero if
 63 058b0118 2005-01-03 devnull .I c
 64 058b0118 2005-01-03 devnull does not occur.
 65 058b0118 2005-01-03 devnull .PP
 66 058b0118 2005-01-03 devnull .I Memcmp
 67 058b0118 2005-01-03 devnull compares its arguments, looking at the first
 68 058b0118 2005-01-03 devnull .I n
 69 058b0118 2005-01-03 devnull bytes only, and returns an integer
 70 058b0118 2005-01-03 devnull less than, equal to, or greater than 0,
 71 058b0118 2005-01-03 devnull according as
 72 058b0118 2005-01-03 devnull .I s1
 73 058b0118 2005-01-03 devnull is lexicographically less than, equal to, or
 74 058b0118 2005-01-03 devnull greater than
 75 058b0118 2005-01-03 devnull .IR s2 .
 76 058b0118 2005-01-03 devnull The comparison is bytewise unsigned.
 77 058b0118 2005-01-03 devnull .PP
 78 058b0118 2005-01-03 devnull .I Memcpy
 79 058b0118 2005-01-03 devnull copies
 80 058b0118 2005-01-03 devnull .I n
 81 058b0118 2005-01-03 devnull bytes from memory area 
 82 058b0118 2005-01-03 devnull .I s2
 83 058b0118 2005-01-03 devnull to
 84 058b0118 2005-01-03 devnull .IR s1 .
 85 058b0118 2005-01-03 devnull It returns
 86 058b0118 2005-01-03 devnull .IR s1 .
 87 058b0118 2005-01-03 devnull .PP
 88 058b0118 2005-01-03 devnull .I Memmove
 89 058b0118 2005-01-03 devnull works like
 90 058b0118 2005-01-03 devnull .IR memcpy ,
 91 058b0118 2005-01-03 devnull except that it is guaranteed to work if
 92 058b0118 2005-01-03 devnull .I s1
 93 058b0118 2005-01-03 devnull and
 94 058b0118 2005-01-03 devnull .IR s2
 95 058b0118 2005-01-03 devnull overlap.
 96 058b0118 2005-01-03 devnull .PP
 97 058b0118 2005-01-03 devnull .I Memset
 98 058b0118 2005-01-03 devnull sets the first
 99 058b0118 2005-01-03 devnull .I n
100 058b0118 2005-01-03 devnull bytes in memory area
101 058b0118 2005-01-03 devnull .I s
102 058b0118 2005-01-03 devnull to the value of byte
103 058b0118 2005-01-03 devnull .IR c .
104 058b0118 2005-01-03 devnull It returns
105 058b0118 2005-01-03 devnull .IR s .
106 058b0118 2005-01-03 devnull .SH SOURCE
107 058b0118 2005-01-03 devnull All these routines have portable C implementations in
108 c3674de4 2005-01-11 devnull .BR \*9/src/lib9 .
109 058b0118 2005-01-03 devnull .\" Most also have machine-dependent assembly language implementations in
110 c3674de4 2005-01-11 devnull .\" .BR \*9/lib9/$objtype .
111 058b0118 2005-01-03 devnull .SH SEE ALSO
112 d32deab1 2020-08-16 rsc .MR strcat (3)
113 058b0118 2005-01-03 devnull .SH BUGS
114 058b0118 2005-01-03 devnull ANSI C does not require
115 058b0118 2005-01-03 devnull .I memcpy
116 058b0118 2005-01-03 devnull to handle overlapping source and destination; on Plan 9, it does, so
117 058b0118 2005-01-03 devnull .I memmove
118 058b0118 2005-01-03 devnull and
119 058b0118 2005-01-03 devnull .I memcpy
120 058b0118 2005-01-03 devnull behave identically.
121 058b0118 2005-01-03 devnull .PP
122 058b0118 2005-01-03 devnull If
123 058b0118 2005-01-03 devnull .I memcpy
124 058b0118 2005-01-03 devnull and
125 058b0118 2005-01-03 devnull .I memmove
126 058b0118 2005-01-03 devnull are handed a negative count, they abort.