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OS_SWINumberFromString
Programmer's Reference Manuals
» Part 15 – SWI Calls
» OS
» OS_SWINumberFromString
OS_SWINumberFromString
(SWI &39)
| Entry | |
|---|---|
| R1 | Pointer to name (control terminated) |
| Exit | |
|---|---|
| R0 | SWI number |
| R1 | Preserved |
Use
The purpose of this call is to convert a SWI name string to a SWI number.
Notes
An error is given if the SWI name is not recognized.
The conversion is as follows:
- A leading X is stripped. If present, it will cause &20000 to be added to the number returned (bit 17)
- System names are checked for. Note that the conversion of SWIs isn’t very bidirectional: the name OS_WriteI+" " can be produced, but only OS_WriteI is recognised
- Modules are scanned. If the module prefix matches the one given, and the suffix to the name is a number, then that number is added to the module’s SWI ‘chunk’ base, and the sum returned. For example, Wimp_&23 returns &400E3, as the Wimp’s chunk number is &400C0
- If the suffix is a name, and this can be matched by the module, the appropriate number is returned. For example, Wimp_Poll returns &400C7