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MEMORY(2) System Calls Manual MEMORY(2)
memccpy, memchr, memcmp, memcpy, memmove, memset - memory operations
void* memccpy(void *s1, void *s2, int c, ulong n)
void* memchr(void *s, int c, ulong n)
int memcmp(void *s1, void *s2, ulong n)
void* memcpy(void *s1, void *s2, ulong n)
void* memmove(void *s1, void *s2, ulong n)
void* memset(void *s, int c, ulong n)
These functions operate efficiently on memory areas (arrays of bytes
bounded by a count, not terminated by a zero byte). They do not check
for the overflow of any receiving memory area.
Memccpy copies bytes from memory area s2 into s1, stopping after the
first occurrence of byte c has been copied, or after n bytes have been
copied, whichever comes first. It returns a pointer to the byte after
the copy of c in s1, or zero if c was not found in the first n bytes of
Memchr returns a pointer to the first occurrence of byte c in the first
n bytes of memory area s, or zero if c does not occur.
Memcmp compares its arguments, looking at the first n bytes only, and
returns an integer less than, equal to, or greater than 0, according as
s1 is lexicographically less than, equal to, or greater than s2. The
comparison is bytewise unsigned.
Memcpy copies n bytes from memory area s2 to s1. It returns s1.
Memmove works like memcpy, except that it is guaranteed to work if s1
and s2 overlap.
Memset sets the first n bytes in memory area s to the value of byte c.
It returns s.
All these routines have portable C implementations in
/sys/src/libc/port. Most also have machine-dependent assembly language
implementations in /sys/src/libc/$objtype.
ANSI C does not require memcpy to handle overlapping source and desti‐
nation; on Plan 9, it does, so memmove and memcpy behave identically.
If memcpy and memmove are handed a negative count, they abort.