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researchv10 Dan Cross

.TH ADDR 3R "630 MTG"
.XE "addr()"
.SH NAME
addr \- return the Word address of a Point in a Bitmap
.SH SYNOPSIS
\f3#include <dmd.h>\f1
.sp
\f3Word \(**addr (b, p)\f1
.br
.B Bitmap \(**b;
.br
.B Point p;\fR
.SH DESCRIPTION
The
.I addr 
function
returns the address of the Word containing the bit
corresponding to the Point
.I p
in the Bitmap
.I b.
.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>
Word *addr();

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

	w = addr (b, p);
	bit = FIRSTBIT >> (p.x%WORDSIZE);
	return (*w&bit)==bit;
}
.fi
.ft R
.RE
.PP
This routine is implemented differently in \f2rol\f1(3L).
.SH SEE ALSO
rol(3L), structure(3R).

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