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				.Dd July 8, 2018
				.Dt Q_QADDQ 3
				.Os
				.Sh NAME
				.Nm Q_QADDQ ,
				.Nm Q_QDIVQ ,
				.Nm Q_QMULQ ,
				.Nm Q_QSUBQ ,
				.Nm Q_NORMPREC ,
				.Nm Q_QMAXQ ,
				.Nm Q_QMINQ ,
				.Nm Q_QCLONEQ ,
				.Nm Q_CPYVALQ
				.Nd fixed-point math functions which operate on two Q numbers
				.Sh SYNOPSIS
				.In sys/qmath.h
				.Ft int
				.Fn Q_QADDQ "QTYPE *a" "QTYPE b"
				.Ft int
				.Fn Q_QDIVQ "QTYPE *a" "QTYPE b"
				.Ft int
				.Fn Q_QMULQ "QTYPE *a" "QTYPE b"
				.Ft int
				.Fn Q_QSUBQ "QTYPE *a" "QTYPE b"
				.Ft int
				.Fn Q_NORMPREC "QTYPE a" "QTYPE b"
				.Ft QTYPE
				.Fn Q_QMAXQ "QTYPE a" "QTYPE b"
				.Ft QTYPE
				.Fn Q_QMINQ "QTYPE a" "QTYPE b"
				.Ft int
				.Fn Q_QCLONEQ "QTYPE *l" "QTYPE r"
				.Ft int
				.Fn Q_QCPYVALQ "QTYPE *l" "QTYPE r"
				.Sh DESCRIPTION
				The
				.Fn Q_QADDQ ,
				.Fn Q_QDIVQ ,
				.Fn Q_QMULQ ,
				and
				.Fn Q_QSUBQ
				functions add, divide, multiply or subtract
				.Fa b
				to/by/from
				.Fa a
				respectively, storing the result in
				.Fa a .
				Both arguments must be initialized with the same fractional radix point.
				.Pp
				The
				.Fn Q_NORMPREC
				function attempts to normalise the precision of
				.Fa a
				and
				.Fa b
				if they differ.
				The greater of the two precisions is preferred if possible, unless that would
				truncate integer component data for the other operand, in which case the highest
				precision that preserves the integer component of both
				.Fa a
				and
				.Fa b
				is selected.
				.Pp
				The
				.Fn Q_QMAXQ
				and
				.Fn Q_QMINQ
				functions return the larger or smaller of
				.Fa a
				and
				.Fa b
				respectively.
				.Pp
				The
				.Fn Q_QCLONEQ
				and
				.Fn Q_QCPYVALQ
				functions attempt to store identical or representational copies of
				.Fa r ,
				in
				.Fa l
				respectively.
				An identical Q number produced by cloning copies the control bits as well as the
				verbatim integer/fractional bits.
				A representational copy only copies the values of
				.Fa r Ap s
				integer and fractional bits, representing them in the bits available per
				.Fa l Ap s
				Q format.
				.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 .
				.Pp
				For more details, see
				.Xr qmath 3 .
				.Sh RETURN VALUES
				The
				.Fn Q_QADDQ ,
				.Fn Q_QDIVQ ,
				.Fn Q_QMULQ ,
				.Fn Q_QSUBQ
				.Fn Q_NORMPREC ,
				.Fn Q_QCLONEQ
				and
				.Fn Q_QCPYVALQ
				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.
				.Er ERANGE is also returned when the precision of arguments
				does not match.
				.Pp
				The
				.Fn Q_QMAXQ
				and
				.Fn Q_QMINQ
				functions return the numerically larger or smaller of their two inputs
				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.