Q_SIGNED(3) FreeBSD Library Functions Manual Q_SIGNED(3)
NAME
Q_SIGNED, Q_LTZ, Q_PRECEQ, Q_QLTQ, Q_QLEQ, Q_QGTQ, Q_QGEQ, Q_QEQ, Q_QNEQ,
Q_OFLOW, Q_RELPREC - fixed-point math comparison and logic functions
SYNOPSIS
#include <sys/qmath.h>
bool
Q_SIGNED(NTYPE n);
bool
Q_LTZ(NTYPE n);
bool
Q_PRECEQ(QTYPE a, QTYPE b);
bool
Q_QLTQ(QTYPE a, QTYPE b);
bool
Q_QLEQ(QTYPE a, QTYPE b);
bool
Q_QGTQ(QTYPE a, QTYPE b);
bool
Q_QGEQ(QTYPE a, QTYPE b);
bool
Q_QEQ(QTYPE a, QTYPE b);
bool
Q_QNEQ(QTYPE a, QTYPE b);
bool
Q_OFLOW(QTYPE q, ITYPE iv);
int
Q_RELPREC(QTYPE a, QTYPE b);
DESCRIPTION
Q_SIGNED() returns true if the numeric data type passed in as n is
signed, or false otherwise.
Q_LTZ() returns true if the numeric value passed in as n is negative
(requires types which use the MSB as the sign bit), or false otherwise.
Q_PRECEQ() returns true if the number of a and b fractional bits is the
same, false otherwise.
The Q_QLTQ(), Q_QLEQ(), Q_QGTQ(), Q_QGEQ(), Q_QEQ() and Q_QNEQ()
functions compare two Q numbers, returning true if a is less than, less
than or equal to, greater than, greater than or equal to, equal to, or
not equal to b respectively, or false otherwise. The integral and
fractional values are used to perform the comparison, without explicit
concern for the underlying number of integer versus fractional bits.
Q_OFLOW() returns true if integer value iv cannot be stored in q without
truncation, or false otherwise.
Q_RELPREC() returns the relative precision of a versus b. In terms of
Qm.n notation, this function returns the difference between the n values
of a and b. For example, a return value of +4 means that a has an
additional 4 bits of fractional precision compared to b.
All of those functions operate on the following data types: s8q_t, u8q_t,
s16q_t, u16q_t, s32q_t, u32q_t, s64q_t, and u64q_t, which are referred to
generically as QTYPE. The ITYPE refers to the stdint(7) integer types.
NTYPE is used to refer to any numeric type and is therefore a superset of
QTYPE and ITYPE.
For more details, see qmath(3).
RETURN VALUES
The Q_SIGNED(), Q_LTZ(), Q_PRECEQ(), Q_QLTQ(), Q_QLEQ(), Q_QGTQ(),
Q_QGEQ(), Q_QEQ(), Q_QNEQ() and Q_OFLOW() functions return expressions
that evaluate to boolean true or false.
Q_RELPREC() returns the relative precision difference as a signed
integer.
SEE ALSO
errno(2), qmath(3), stdint(7)
HISTORY
The qmath(3) functions first appeared in FreeBSD 13.0.
AUTHORS
The qmath(3) functions and this manual page were written by Lawrence
Stewart <
[email protected]> and sponsored by Netflix, Inc.
FreeBSD 14.1-RELEASE-p8 July 8, 2018 FreeBSD 14.1-RELEASE-p8