---
title: OSDecrementAtomic16
framework: kernel
role: symbol
role_heading: Function
path: kernel/1576468-osdecrementatomic16
---

# OSDecrementAtomic16

16-bit decrement operation, performed atomically with respect to all devices that participate in the coherency architecture of the platform.

## Declaration

```occ
SInt16 OSDecrementAtomic16(volatile SInt16 *address);
```

## Parameters

- `address`: The 2-byte aligned address of the value to update atomically.

## Return Value

Return Value The value before the decrement.

## Discussion

Discussion The OSDecrementAtomic16 function decrements the value at the specified address by one and returns the original value. This function guarantees atomicity only with main system memory. It is specifically unsuitable for use on noncacheable memory such as that in devices; this function cannot guarantee atomicity, for example, on memory mapped from a PCI device. Previous incarnations of this function incorporated a memory barrier on systems with weakly-ordered memory architectures, but current versions contain no barriers.

## See Also

### Decrement

- [OSDecrementAtomic](kernel/1576455-osdecrementatomic.md)
- [OSDecrementAtomic8](kernel/1576458-osdecrementatomic8.md)
- [OSDecrementAtomic64](kernel/1576449-osdecrementatomic64.md)