powerof2(9) - NetBSD Manual Pages

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ROUNDUP(9)             NetBSD Kernel Developer's Manual             ROUNDUP(9)


NAME
roundup -- macros for counting and rounding
SYNOPSIS
#include <sys/param.h> size howmany(x, size); size roundup(x, size); size rounddown(x, size); size roundup2(x, size); int powerof2(x);
DESCRIPTION
The roundup() and rounddown() macros return an integer from rounding x up and down, respectively, to the next size. The howmany() macro in turn reveals how many times size fits into x, rounding the residual up. The roundup2() macro also rounds up, but with the assumption that size is a power of two. If x is indeed a power of two, powerof2() return 1.
RETURN VALUES
The return value is an integer from the respective operation. If x is 0, all macros except powerof2() return 0. The behavior is undefined if size is 0.
EXAMPLES
The following example rounds the variable rx to a 32-bit boundary: uint16_t rx; ... rx = roundup2(rx, sizeof(uint32_t));
SEE ALSO
ilog2(3), param(3), imax(9)
CAVEATS
All described macros make no assumptions about the type of the parame- ters. These are implicitly assumed to be unsigned integers. NetBSD 6.0 June 1, 2011 NetBSD 6.0
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