April 11, 2007 ATOMIC_DEC 3

### NAME

atomic_dec, atomic_dec_32, atomic_dec_uint, atomic_dec_ulong, atomic_dec_ptr, atomic_dec_64, atomic_dec_32_nv, atomic_dec_uint_nv, atomic_dec_ulong_nv, atomic_dec_ptr_nv, atomic_dec_64_nv - atomic decrement operations

### SYNOPSIS

```void` atomic_dec_32(```volatile uint32_t *ptr`)
```void` atomic_dec_uint(```volatile unsigned int *ptr`)
```void` atomic_dec_ulong(```volatile unsigned long *ptr`)
```void` atomic_dec_ptr(```volatile void *ptr`)
```void` atomic_dec_64(```volatile uint64_t *ptr`)
```uint32_t` atomic_dec_32_nv(```volatile uint32_t *ptr`)
```unsigned` `int` atomic_dec_uint_nv(```volatile unsigned int *ptr`)
```unsigned` `long` atomic_dec_ulong_nv(```volatile unsigned long *ptr`)
```void``*` atomic_dec_ptr_nv(```volatile void *ptr`)
```uint64_t` atomic_dec_64_nv(```volatile uint64_t *ptr`)

### DESCRIPTION

The atomic_dec family of functions decrement (by one) the variable referenced by ```ptr` in an atomic fashion.

The *_nv(``) variants of these functions return the new value.

The 64-bit variants of these functions are available only on platforms that can support atomic 64-bit memory access. Applications can check for the availability of 64-bit atomic memory operations by testing if the pre-processor macro ```__HAVE_ATOMIC64_OPS` is defined.

### SEE ALSO

atomic_ops(3)

### HISTORY

The atomic_dec functions first appeared in NetBSD5.0.