.fp 5 CW
.de Af
.ds ;G \\*(;G\\f\\$1\\$3\\f\\$2
.if !\\$4 .Af \\$2 \\$1 "\\$4" "\\$5" "\\$6" "\\$7" "\\$8" "\\$9"
..
.de aF
.ie \\$3 .ft \\$1
.el \{\
.ds ;G \&
.nr ;G \\n(.f
.Af "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7" "\\$8" "\\$9"
\\*(;G
.ft \\n(;G \}
..
.de L
.aF 5 \\n(.f "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7"
..
.de LR
.aF 5 1 "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7"
..
.de RL
.aF 1 5 "\\$1" "\\$2" "\\$3" "\\$4" "\\$5" "\\$6" "\\$7"
..
.de EX		\" start example
.ta 1i 2i 3i 4i 5i 6i
.PP
.RS 
.PD 0
.ft 5
.nf
..
.de EE		\" end example
.fi
.ft
.PD
.RE
.PP
..
.TH SWAP 3
.SH NAME
swap \- integral representation conversion routines
.SH SYNOPSIS
.L "#include <swap.h>"
.sp
.L "int swapop(const void* internal, const void* external, int width);
.L "int_max swapget(int op, const void* from, int width);"
.L "void* swapput(int op, void* to, int width, int_max value);"
.L "void* swapmem(int op, const void* from, void* to, size_t n);"
.SH DESCRIPTION
These routines convert integral constants between internal and
external representations.
They are used to handle binary data generated by foreign programs.
New binary data representations should use the compact canonical form
provided by the
.IR sfio (3)
routines
.L sfputu
and
.LR sgetu .
.PP
.L swapop
returns the swap operation required to convert the
.L width 
byte integer
.L external
to the
.L width
byte integer
.LR internal .
The swap operation is a bit mask:
.TP
.L 0
No swapping necessary.
.TP
.L 1
Swap byte
.L 0
with byte
.LR 1 .
.TP
.L 2
Swap bytes
.L 0
and
.L 1
with bytes
.L 2
and 
.LR 3 .
.TP
.L 4
Swap bytes
.L 0-3
with bytes
.LR 4-7 ,
and so on.
The largest native integral type is defined by the macro
.L int_max
in the header
.L <int.h>
described in
.IR int (3).
.PP
.L swapget 
returns the
.L width
byte integer in the buffer
.LR from ,
swapped according to
.LR op .
.PP
.L swapput 
copies the
.L width
byte integer
.L value
into the buffer
.LR to ,
swapped according to
.LR op .
.L to
is returned.
.PP
.L swapmem
swaps 
.L n
bytes from the buffer
.L from
to the buffer
.L to
according to 
.LR op .
.L to
and 
.L from
may be the same.
.SH "SEE ALSO"
int(3)