ctod(9) [netbsd man page]

CTOD(9) 						   BSD Kernel Developer's Manual						   CTOD(9)

NAME

     ctod -- macros related to bytes, pages, and disk blocks

SYNOPSIS

     #include <sys/param.h>

     size
     ctod(size x);

     size
     dtoc(size x);

     size
     ctob(size x);

     size
     btoc(size x);

     size
     dbtob(size x);

     size
     btodb(size x);

DESCRIPTION

     The ctod family of macros can be used to convert between bytes, pages (``clicks''), and disk blocks.

     The following table lists the possible conversions:

	   Macro	   From 	   To
	   ctod()	   pages	   disk blocks
	   dtoc()	   disk blocks	   pages
	   ctob()	   pages	   bytes
	   btoc()	   bytes	   pages
	   dbtob()	   disk blocks	   bytes
	   btodb()	   bytes	   disk blocks

     These are typical macros that may appear with different names in other operating systems.	Examples include btop() and btopr() in Solaris.

SEE ALSO

     param(3)

HISTORY

     Some of these macros appeared in Version 7 AT&T UNIX.

CAVEATS

     The described macros make no assumptions about the type of the input parameter.  A caller should ensure that neither integer overflow nor
     integer underflow are possible.

BSD
								   April 8, 2011							       BSD

ROUNDUP(9)						   BSD 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.

BSD
								   June 1, 2011 							       BSD