git: 9front

ref: b220b86cb19d79e53412bb28b7ee0def88edbcf7
dir: /sys/man/2/muldiv/

View raw version
.TH MULDIV 2
.SH NAME
muldiv, umuldiv \- high-precision multiplication and division
.SH SYNOPSIS
.B #include <u.h>
.br
.B #include <libc.h>
.PP
.B
long muldiv(long a, long b, long c)
.PP
.B
ulong umuldiv(ulong a, ulong b, ulong c)
.SH DESCRIPTION
.I Muldiv
returns
.BR a*b/c ,
using a
.B vlong
to hold the intermediate result.
.I Umuldiv
is the equivalent for unsigned integers.
They can be used to scale integer values without worry about
overflowing the intermediate result.
.PP
On some architectures, these routines can generate a trap if the
final result does not fit in a
.B long
or
.BR ulong ;
on others they will silently truncate.