=> R0-R9 = as required for target SWI
R12 = target SWI number
<= dependent on SWI called
This call is identical to OS_CallASWI, except that it uses R12 to specify the target SWI. This may be more convenient in some environments. In particular under APCS-R, R10 is the stack limit pointer, which must be preserved at all times; if a SWI called using OS_CallASWI were to abort or generate an error the run-time library would usually examine R10 and decide that it had no stack to handle the abort or error. Therefore APCS-R libraries must use OS_CallASWIR12 (R12 being a scratch register under APCS-R).
Provided by RISC OS 3.70+, and also the CallASWI module for earlier versions of RISC OS.
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