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researchv10 Dan Cross

.ds ZZ DEVELOPMENT PACKAGE
.TH ROL 3L "630 MTG"
.XE "rol()"
.XE "ror()"
.SH NAME
rol, ror \- rotate bits
.SH SYNOPSIS
.B int rol (x, n)
.sp
.B int ror (x, n)
.sp
.B int x, n; 
.SH DESCRIPTION
The
.I rol
function
returns
.I x
logically bit-rotated left by
.I n.
.PP
The
.I ror
function
returns
.I x
logically bit-rotated right by
.I n.
.SH EXAMPLE
The following subroutine can be used to determine whether a Point
.I p
in a Bitmap
.I b
is on or off (returning 1 or 0, respectively).
.PP
.RS 3
.nf
.ft CM
#include <dmd.h>

pixel (b, p)
Bitmap *b;
Point	p;
{
	Word *w;

	w = addr (b, p);
	return ( (rol (*w, p.x%\s-1WORDSIZE\s+1)
		& \s-1FIRSTBIT\s+1)==\s-1FIRSTBIT\s+1);
}
\fR
.fi
.RE
.PP
This routine is implemented differently in
.IR addr (3R).
.SH SEE ALSO
addr(3R).

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