Entry | |
---|---|
R0 | 24 (&18) |
R1 | Low address (inclusive) |
R2 | High address (exclusive) |
Exit | |
---|---|
R0 | Preserved |
R1 | Access flags |
R2 | Preserved |
This call examines a given logical address range and returns a set of flags indicating the access rights that programs have when accessing the block of memory. It is essentially a more verbose version of OS_ValidateAddress. However, unlike OS_ValidateAddress, it does not issue Service_ValidateAddress when given an unknown region.
This call is supported by RISC OS Select and RISC OS 5.21.
Bit | Meaning |
---|---|
0 | Range is completely readable in user mode |
1 | Range is completely writable in user mode |
2 | Range is completely readable in privileged modes |
3 | Range is completely writable in privileged modes |
4 | Range is partially readable in user mode |
5 | Range is partially writable in user mode |
6 | Range is partially readable in privileged modes |
7 | Range is partially writable in privileged modes |
8 | Range is completely physically mapped |
9 | Range is completely abortable (aborts handled by code) |
12 | Range is partially physically mapped |
13 | Range is partially abortable (aborts handled by code) |
All other bits are reserved for future expansion.