OS_Module 6 (changes)
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OS SWI Calls
» OS_Module
» OS_Module 6
OS_ Module 6
(SWI &1E)
| Entry | |
|---|---|
| R0 | 6 |
| R3 | Size of area |
| Exit | |
|---|---|
| R0 | Preserved |
| R2 | Block |
| R3 | Preserved |
Use
The purpose of this call is to return an area of free RMA claimed for use.
Notes
Starting with RISC OS 2.01, memory allocated by this call will have a start address of (n MOD 16)=4. This can be used to help to improve performance by allowing programmers to easily align their code/data to cache-line boundaries (assuming a 16 byte cache line size). In RISC OS 5.00 the alignment was changed to (n MOD 32)=20, which can be useful for machines with 32 byte cache lines.
OS_Module 24 can be used to allocate a “naturally aligned” block at an arbitrary power of two alignment (i.e. (n MOD x)=0).
See also
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