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 9.0