jehanne/sys/src/lib/draw/bytesperline.c

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/*
* This file is part of the UCB release of Plan 9. It is subject to the license
* terms in the LICENSE file found in the top-level directory of this
* distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
* part of the UCB release of Plan 9, including this file, may be copied,
* modified, propagated, or distributed except according to the terms contained
* in the LICENSE file.
*/
#include <u.h>
#include <lib9.h>
#include <draw.h>
static
int
unitsperline(Rectangle r, int d, int bitsperunit)
{
uint32_t l, t;
if(d <= 0 || d > 32) /* being called wrong. d is image depth. */
abort();
if(r.min.x >= 0){
l = (r.max.x*d+bitsperunit-1)/bitsperunit;
l -= (r.min.x*d)/bitsperunit;
}else{ /* make positive before divide */
t = (-r.min.x*d+bitsperunit-1)/bitsperunit;
l = t+(r.max.x*d+bitsperunit-1)/bitsperunit;
}
return l;
}
int
wordsperline(Rectangle r, int d)
{
return unitsperline(r, d, 8*sizeof(uint32_t));
}
int
bytesperline(Rectangle r, int d)
{
return unitsperline(r, d, 8);
}