swaplwbytes.3

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3 代码 · 共 55 行

.TH swap_lw_bytes 3
.SH Name
swap_lw_bytes, swap_word_bytes, swap_words \- perform byte swapping operations
.SH Syntax
unsigned int swap_lw_bytes\^(\^\fIbuffer\fP\^)
.br
unsigned int \fIbuffer\fP\^;
.sp
unsigned int swap_word_bytes\^(\^\fIbuffer\fP\^)
.br
unsigned int \fIbuffer\fP\^;
.sp
unsigned int swap_words\^(\^\fIbuffer\fP\^)
.br
unsigned int \fIbuffer\fP\^;
.SH Arguments
.IP \fIbuffer\fP 1.0i
Specifies a 32-bit (4 bytes) quantity.
.SH Description
.NXR "byte swapping"
The
.PN "swap_lw_bytes" 
routine performs a long word byte swap.
The
.PN "swap_word_bytes" 
routine performs a short word byte swap.
The
.PN "swap_words" 
routine performs a word byte swap.
Because Digital devices support the little endian model of byte
ordering, there is
a need for these byte swapping routines.
.PP
For the purposes of the following discussion, a long word 
is equal to 4 bytes; a
short word is equal to 2 bytes; and 1 byte is equal to 8 bits.
The
.PN "swap_lw_bytes" 
routine takes the 32-bit quantity specified by the
\fIbuffer\fP
argument and swaps all four bytes.
The
.PN "swap_word_bytes" 
routine takes the 32-bit quantity specified by the
\fIbuffer\fP
argument and swaps the individual bytes that make up each byte of the
32-bit quantity.
The
.PN "swap_words" 
routine takes the 32-bit quantity specified by the
\fIbuffer\fP
argument and swaps the two words.
.SH Return Values
These routines return the result of the byte swapping.