ROUNDUP(9)

ROUNDUP(9) | 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 parameters. These are implicitly assumed to be unsigned integers.

June 1, 2011 | NetBSD 7.1