'\" te
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.TH ATOMIC_CAS 3C "May 13, 2005"
.SH NAME
atomic_cas, atomic_cas_8, atomic_cas_uchar, atomic_cas_16, atomic_cas_ushort,
atomic_cas_32, atomic_cas_uint, atomic_cas_ulong, atomic_cas_64, atomic_cas_ptr
\- atomic compare and swap operations
.SH SYNOPSIS
.LP
.nf
#include <atomic.h>

\fBuint8_t\fR \fBatomic_cas_8\fR(\fBvolatile uint8_t *\fR\fItarget\fR, \fBuint8_t\fR \fIcmp\fR,
     \fBuint8_t\fR \fInewval\fR);
.fi

.LP
.nf
\fBuchar_t\fR \fBatomic_cas_uchar\fR(\fBvolatile uchar_t *\fR\fItarget\fR, \fBuchar_t\fR \fIcmp\fR,
     \fBuchar_t\fR \fInewval\fR);
.fi

.LP
.nf
\fBuint16_t\fR \fBatomic_cas_16\fR(\fBvolatile uint16_t *\fR\fItarget\fR, \fBuint16_t\fR \fIcmp\fR,
     \fBuint16_t\fR \fInewval\fR);
.fi

.LP
.nf
\fBushort_t\fR \fBatomic_cas_ushort\fR(\fBvolatile ushort_t *\fR\fItarget\fR, \fBushort_t\fR \fIcmp\fR,
     \fBushort_t\fR \fInewval\fR);
.fi

.LP
.nf
\fBuint32_t\fR \fBatomic_cas_32\fR(\fBvolatile uint32_t *\fR\fItarget\fR, \fBuint32_t\fR \fIcmp\fR,
     \fBuint32_t\fR \fInewval\fR);
.fi

.LP
.nf
\fBuint_t\fR \fBatomic_cas_uint\fR(\fBvolatile uint_t *\fR\fItarget\fR, \fBuint_t\fR \fIcmp\fR,
     \fBuint_t\fR \fInewval\fR);
.fi

.LP
.nf
\fBulong_t\fR \fBatomic_cas_ulong\fR(\fBvolatile ulong_t *\fR\fItarget\fR, \fBulong_t\fR \fIcmp\fR,
     \fBulong_t\fR \fInewval\fR);
.fi

.LP
.nf
\fBuint64_t\fR \fBatomic_cas_64\fR(\fBvolatile uint64_t *\fR\fItarget\fR, \fBuint64_t\fR \fIcmp\fR,
     \fBuint64_t\fR \fInewval\fR);
.fi

.LP
.nf
\fBvoid *\fR\fBatomic_cas_ptr\fR(\fBvolatile void *\fR\fItarget\fR, \fBvoid *\fR\fIcmp\fR,
     \fBvoid *\fR\fInewval\fR);
.fi

.SH DESCRIPTION
.sp
.LP
These functions enable a compare and swap operation to occur atomically. The
value stored in \fItarget\fR is compared with \fIcmp\fR. If these values are
equal, the value stored in \fItarget\fR is replaced with \fInewval\fR. The old
value stored in \fItarget\fR is returned by the function whether or not the
replacement occurred.
.SH RETURN VALUES
.sp
.LP
These functions return the old value of *\fItarget\fR.
.SH ERRORS
.sp
.LP
No errors are defined.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR atomic_add (3C),
.BR atomic_and (3C),
.BR atomic_bits (3C),
.BR atomic_dec (3C),
.BR atomic_inc (3C),
.BR atomic_or (3C),
.BR atomic_swap (3C),
.BR membar_ops (3C),
.BR attributes (7),
.BR atomic_ops (9F)