OS_Memory 19 Output Function (changes)
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OS SWI Calls
» OS_Memory
» OS_Memory 19
» Output Function
Output Function
| Entry | (32 bit addresses) |
|---|---|
| R0 | Logical address of start of region |
| R1 | Physical address of start of region |
| R2 | Length of region |
| R3 | Flags: |
| Bit 0: Bounce buffer must be used | |
| Bits 1+: Reserved | |
| R9 | R4 from OS_Memory 19 input / R9 output from previous Output Function call |
| R12 | R1 from OS_Memory 19 input |
| SVC32 mode, interrupts enabled | |
| Entry | (64 bit addresses) |
|---|---|
| R0 | Logical address of start of region |
| R1,R2 | Physical address of start of region |
| R3 | Flags: |
| Bit 0: Bounce buffer must be used | |
| Bits 1+: Reserved | |
| R4 | Length of region |
| R9 | R4 from OS_Memory 19 input / R9 output from previous Output Function call |
| R12 | R1 from OS_Memory 19 input |
| SVC32 mode, interrupts enabled | |
| Exit | |
|---|---|
| R9 | New R9 for next Output call |
| R0-R3, R12 | Corrupt |
| - | All other registers preserved |
Use
OS_Memory 19 calls this function to pass the details of processed buffer regions to your code.
Notes
Bit 11 of the OS_Memory 19 flags should be used to indicate whether your code is using the 32 bit or 64 bit interface.
If OS_Memory 19 indicates that a bounce buffer must be used for a region, then it’s imperative to not perform DMA to that region, and only perform CPU access instead.
See also
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