MEMCHR(9F) Kernel Functions for Drivers MEMCHR(9F)
NAME
memchr, memcmp, memcpy, memmove, memset - Memory operations
SYNOPSIS
#include <sys/sunddi.h>
void *memchr(
const void *s,
int c,
size_t n);
int memcmp(
const void *s1,
const void *s2,
size_t n);
void *memcpy(
void *restrict s1,
const void *restrict s2,
size_t n);
void *memmove(
void *s1,
const void *s2,
size_t n);
void *memset(
void *s,
int c,
size_t n);
INTERFACE LEVEL
illumos DDI specific (illumos DDI).
PARAMETERS
dst Pointers to character strings.
n Count of characters to be copied.
s1,
s2 Pointers to character strings.
DESCRIPTION
These functions operate as efficiently as possible on memory areas
(arrays of bytes bounded by a count, not terminated by a null
character). They do not check for the overflow of any receiving
memory area.
The
memchr() function returns a pointer to the first occurrence of
c (converted to an
unsigned char) in the first
n bytes (each
interpreted as an
unsigned char) of memory area
s, or a null pointer
if
c does not occur.
The
memcmp() function compares its arguments, looking at the first
n bytes (each interpreted as an
unsigned char), 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 when taken
to be unsigned characters.
The
memcpy() function copies
n bytes from memory area
s2 to
s1. It
returns
s1. If copying takes place between objects that overlap, the
behavior is undefined.
The
memmove() function copies
n bytes from memory area
s2 to memory
area
s1. Copying between objects that overlap will take place
correctly. It returns
s1.
The
memset() function sets the first
n bytes in memory area
s to the
value of
c (converted to an
unsigned char). It returns
s.
USAGE
Using
memcpy() might be faster than using
memmove() if the
application knows that the objects being copied do not overlap.
CONTEXT
These functions can be called from user, interrupt, or kernel
context.
SEE ALSO
bcopy(9F),
ddi_copyin(9F),
strcpy(9F) Writing Device Drivers January 15, 2014 MEMCHR(9F)
