Writes a 32-bit value to a variable only if the previous variable content was NIL. This function is non-interruptable in order to simplify communication between application tasks that run at interrupt level. It can be used to implement "mail boxes" between tasks when used in conjunction with MidiReadSync.
pascal void* MidiWriteSync(void *adrMem, void *val);
adrMem- is the address of a variable to be modified.
val- is a 32-bit value to write.
The result is the previous content of the variable.
Example to be supplied.