Legacy Document

Important: The information in this document is obsolete and should not be used for new development.

Inside Macintosh: Networking With Open Transport / Part 2 - Open Transport Reference

Chapter 27 - Utilities Reference / Functions

OTAtomicAdd32
Atomically adds a 32-bit value to a memory location.

C INTERFACE
SInt32 OTAtomicAdd32(SInt32 toAdd,
                     SInt32* where)
C++ INTERFACE
None. C++ applications use the C interface to this function.

PARAMETERS

toAdd
A signed 32-bit value to add to the value referenced by the where parameter.
where
A pointer to a signed 32-bit value that is added to the value specified by the parameter toAdd.
function result
The sum of the values specified by the function's parameters.

DISCUSSION
This function atomically adds the signed 32-bit value specified by the parameter toAdd to the value referenced by the where parameter and returns the result. It also stores the result in the location referenced by the where parameter.
You can use this function to subtract from the toAdd value referenced by the where parameter by reversing the sign of toAdd.

WARNING
The pointer where must be on a 4-byte boundary, or calling this function may hang the machine.
Use the OTAtomicAdd16 function to add two 16-bit values.
Use the OTAtomicAdd8 function to add two 8-bit values.