'\" te
.\" Copyright (c) 2009, Sun Microsystems, Inc. All Rights Reserved.
.TH atomic_cas 3C "13 May 2005" "SunOS 5.11" "Standard C Library Functions"
.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(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
Interface StabilityCommitted
_
MT-LevelMT-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBatomic_add\fR(3C), \fBatomic_and\fR(3C), \fBatomic_bits\fR(3C), \fBatomic_dec\fR(3C), \fBatomic_inc\fR(3C), \fBatomic_or\fR(3C), \fBatomic_swap\fR(3C), \fBmembar_ops\fR(3C), \fBattributes\fR(5), \fBatomic_ops\fR(9F)