'\" te
.\" Copyright (c) 2006, Sun Microsystems, Inc. All Rights Reserved.
.TH atomic_dec 9F "16 Jan 2006" "SunOS 5.11" "Kernel Functions for Drivers"
.SH NAME
atomic_dec, atomic_dec_8, atomic_dec_uchar, atomic_dec_16, atomic_dec_ushort, atomic_dec_32, atomic_dec_uint, atomic_dec_ulong, atomic_dec_64, atomic_dec_ptr, atomic_dec_8_nv, atomic_dec_uchar_nv, atomic_dec_16_nv, atomic_dec_ushort_nv, atomic_dec_32_nv, atomic_dec_uint_nv, atomic_dec_ulong_nv, atomic_dec_64_nv, atomic_dec_ptr_nv \- atomic decrement operations
.SH SYNOPSIS
.LP
.nf
#include <sys/atomic.h>

\fBvoid\fR \fBatomic_dec_8\fR(\fBvolatile uint8_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBvoid\fR \fBatomic_dec_uchar\fR(\fBvolatile uchar_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBvoid\fR \fBatomic_dec_16\fR(\fBvolatile uint16_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBvoid\fR \fBatomic_dec_ushort\fR(\fBvolatile ushort_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBvoid\fR \fBatomic_dec_32\fR(\fBvolatile uint32_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBvoid\fR \fBatomic_dec_uint\fR(\fBvolatile uint_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBvoid\fR \fBatomic_dec_ulong\fR(\fBvolatile ulong_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBvoid\fR \fBatomic_dec_64\fR(\fBvolatile uint64_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBvoid\fR \fBatomic_dec_ptr\fR(\fBvolatile void *\fR\fItarget\fR);
.fi

.LP
.nf
\fBuint8_t\fR \fBatomic_dec_8_nv\fR(\fBvolatile uint8_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBuchar_t\fR \fBatomic_dec_uchar_nv\fR(\fBvolatile uchar_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBuint16_t\fR \fBatomic_dec_16_nv\fR(\fBvolatile uint16_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBushort_t\fR \fBatomic_dec_ushort_nv\fR(\fBvolatile ushort_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBuint32_t\fR \fBatomic_dec_32_nv\fR(\fBvolatile uint32_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBuint_t\fR \fBatomic_dec_uint_nv\fR(\fBvolatile uint_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBulong_t\fR \fBatomic_dec_ulong_nv\fR(\fBvolatile ulong_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBuint64_t\fR \fBatomic_dec_64_nv\fR(\fBvolatile uint64_t *\fR\fItarget\fR);
.fi

.LP
.nf
\fBvoid *\fR\fBatomic_dec_ptr_nv\fR(\fBvolatile void *\fR\fItarget\fR);
.fi

.SH DESCRIPTION
.sp
.LP
These functions enable the decrementing (by one) of the value stored in \fItarget\fR to occur in an atomic manner.
.SH RETURN VALUES
.sp
.LP
The *\fB_nv()\fR variants of these functions return the new value of \fItarget\fR.
.SH ERRORS
.sp
.LP
No errors are defined.
.SH CONTEXT
.sp
.LP
These functions can be called from user, interrupt, or kernel context.
.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
.TE

.SH SEE ALSO
.sp
.LP
\fBatomic_add\fR(9F), \fBatomic_and\fR(9F), \fBatomic_bits\fR(9F), \fBatomic_cas\fR(9F), \fBatomic_inc\fR(9F), \fBatomic_or\fR(9F), \fBatomic_swap\fR(9F), \fBmembar_ops\fR(9F), \fBattributes\fR(5), \fBatomic_ops\fR(3C)
.SH NOTES
.sp
.LP
The *\fB_nv()\fR variants are substantially more expensive on some platforms than the versions that do not return values. Do not use them unless you need to know the new value atomically (for example, when decrementing a reference count and checking whether it went to zero).