OS_SWINumberToString (changes)
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OS SWI Calls
» OS_SWINumberToString
OS_SWINumberToString
(SWI &38)
| Entry | |
|---|---|
| R0 | SWI number |
| R1 | Pointer to buffer |
| R2 | Buffer length |
| Exit | |
|---|---|
| R0 | Preserved |
| R1 | Preserved |
| R2 | Length of string in buffer including terminator |
Use
The purpose of this call is to convert a SWI number to a string containing its SWI name.
Notes
The returned string is null-terminated, and starts with an X if the SWI number has bit 17 set.
SWI numbers < &200 have an ‘OS_’ prefix to the main part, and a SWI-dependent end section (which is ‘Undefined’ for unknown OS SWIs).
SWI numbers in the range &100 to &1FF are converted in the form OS_WriteI+"A", or OS_WriteI+23 if the character is not a printable one.
SWI numbers >= &200 are looked for in modules. If a suitable name is found, it is given in the form module_name or module_number, eg. Wimp_Initialise, Wimp_32. If no name is found in the modules, the string ‘User’ is returned.
The PRM incorrectly states that this SWI returns the length of the string; it actually returns the length of the string and the terminator.
See also
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