RISCOS_MapInIO (changes)
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Hardware Abstraction Layer
» RISC OS entry points from HAL
» RISCOS_MapInIO
RISCOS_MapInIO
(OS entry #3)
void *RISCOS_MapInIO(unsigned int flags, void *phys, unsigned int size)
| Entry | |
|---|---|
| flags | Bits 0-19: B, C, TEX, AP and (for VMSAv6) APX flags for L1 page table section map entry |
| Bit 20: Doubly map region | |
| Bit 21: AP flags specified (otherwise, default to SVC RW access, User none) | |
| Other bits reserved | |
| phys | Physical address to map in |
| size | Number of bytes of memory to map in |
| Exit | |
|---|---|
| - | Virtual address corresponding to phys |
| 0 for failure |
Use
This routine is used to map in IO memory for the HAL’s usage. Normally it would only be called during the execution of HAL_Init. Once mapped in the IO space cannot be released.
It returns the resultant virtual address corresponding to phys, or 0 for failure. Failure can only occur if no RAM is available for page tables, or if the virtual address space is exhausted.
Note that the flags passed in in bits 0-19 of R0 must be in the correct form for use in an L1PT section mapping (1MB page).
A doubly-mapped region should only be requested if the base physical address and size are multiples of 1MB.
See also
Information sources: Kernel.Docs.HAL.HAL_API, Kernel.hdr.OSEntries in CVS
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