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.Dd July 8, 2018
.Dt Q_QADDI 3
.Os
.Sh NAME
.Nm Q_QADDI ,
.Nm Q_QDIVI ,
.Nm Q_QMULI ,
.Nm Q_QSUBI ,
.Nm Q_QFRACI ,
.Nm Q_QCPYVALI
.Nd fixed-point math functions which apply integers to a Q number
.Sh SYNOPSIS
.In sys/qmath.h
.Ft int
.Fn Q_QADDI "QTYPE *a" "ITYPE b"
.Ft int
.Fn Q_QDIVI "QTYPE *a" "ITYPE b"
.Ft int
.Fn Q_QMULI "QTYPE *a" "ITYPE b"
.Ft int
.Fn Q_QSUBI "QTYPE *a" "ITYPE b"
.Ft int
.Fn Q_QFRACI "QTYPE *q" "ITYPE n" "ITYPE d"
.Ft int
.Fn Q_QCPYVALI "QTYPE *q" "ITYPE i"
.Sh DESCRIPTION
The
.Fn Q_QADDI ,
.Fn Q_QDIVI ,
.Fn Q_QMULI
and
.Fn Q_QSUBI
functions add, divide, multiply or subtract
.Fa b
to/by/from
.Fa a
respectively, storing the result in
.Fa a .
.Pp
The
.Fn Q_QFRACI
function computes the fraction
.Fa n
divided by
.Fa d
and stores the fixed-point result in
.Fa q .
.Pp
The
.Fn Q_QCPYVALI
function overwrites
.Fa q Ap s
integer and fractional bits with the Q representation of integer value
.Fa i .
.Pp
All of those functions operate on
the following data types:
.Vt s8q_t ,
.Vt u8q_t ,
.Vt s16q_t ,
.Vt u16q_t ,
.Vt s32q_t ,
.Vt u32q_t ,
.Vt s64q_t ,
and
.Vt u64q_t ,
which are referred to generically as
.Fa QTYPE .
The
.Fa ITYPE
refers to the
.Xr stdint 7
integer types.
.Pp
For more details, see
.Xr qmath 3 .
.Sh RETURN VALUES
.Fn Q_QADDI ,
.Fn Q_QDIVI ,
.Fn Q_QMULI ,
.Fn Q_QSUBI ,
.Fn Q_QFRACI
and
.Fn Q_QCPYVALI
functions return 0 on success, or an errno on failure.
.Er EINVAL
is returned for divide-by-zero.
.Er EOVERFLOW
and
.Er ERANGE
are returned for overflow and underflow respectively.
.Sh SEE ALSO
.Xr errno 2 ,
.Xr qmath 3 ,
.Xr stdint 7
.Sh HISTORY
The
.Xr qmath 3
functions first appeared in
.Fx 13.0 .
.Sh AUTHORS
.An -nosplit
The
.Xr qmath 3
functions and this manual page were written by
.An Lawrence Stewart Aq Mt lstewart@FreeBSD.org
and sponsored by Netflix, Inc.
