atomic_op.2

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 2 代码 · 共 60 行

.TH atomic_op 2
.SH Name
atomic_op \- perform test and set operation.
.SH Syntax
.nf
.ft B 
#include <sys/lock.h>
.PP
.ft B 
int atomic_op(\fIop, addr\fR)
int \fIop\fR;
int \fI*addr\fR;
.fi
.SH Arguments
.IP \fIop\fR 15
This argument is the operation type.  If the operation type is ATOMIC_SET,
this call specifies the test and set operation on location \fIaddr\fR.
If the operation type is ATOMIC_CLEAR, this call specifies the clear
operation on location \fIaddr\fR.
.IP \fIaddr\fR 15
This is the target address of the operation.
.SH Description
.NXR "interlocked access"
.NXR "interlocked access" "test and set" "test and clear"
.NXR "test and set" "test and clear"
The 
.PN atomic_op 
call provides test and set operation at a user address.
.PP
For RISC systems, 
.PN atomic_op
is executed as a system call.
For VAX systems, a system call is not executed for
this library function.
.SH Return Values
If the atomic_op operation succeeds,
then 0 is returned.  Otherwise a \-1 is returned,
and a more specific error code is stored in \fIerrno\fP.
.SH Diagnostics
.TP 15
[EBUSY]
The location specified by 
.I addr
is already set.
.TP
[EINVAL]
The 
.I op
is not a valid operation type.
.TP
[EACCES]
The address specified in 
.I addr
is not write accessible.
.TP
[EALIGN]
The
.I addr
is not on an integer boundary.