blob: 1c14a4c4810491e4f7942804656061cf90197140 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
|
/*
FUNCTION
<<swab>>---swap adjacent bytes
SYNOPSIS
#include <unistd.h>
void swab(const void *<[in]>, void *<[out]>, ssize_t <[n]>);
DESCRIPTION
This function copies <[n]> bytes from the memory region
pointed to by <[in]> to the memory region pointed to by
<[out]>, exchanging adjacent even and odd bytes.
PORTABILITY
<<swab>> requires no supporting OS subroutines.
*/
#include <unistd.h>
void
_DEFUN (swab, (b1, b2, length),
const void *b1,
void *b2,
ssize_t length)
{
const char *from = b1;
char *to = b2;
ssize_t ptr;
for (ptr = 1; ptr < length; ptr += 2)
{
char p = from[ptr];
char q = from[ptr-1];
to[ptr-1] = p;
to[ptr ] = q;
}
if (ptr == length) /* I.e., if length is odd, */
to[ptr-1] = 0; /* then pad with a NUL. */
}
|