ScreenModes_ReadInfo 2 (changes)
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ScreenModes
» SWI Calls
» ScreenModes_ReadInfo
» ScreenModes_ReadInfo 2
ScreenModes_ReadInfo 2
(SWI &487C0)
| Entry | |
|---|---|
| R0 | 2 |
| Exit | |
|---|---|
| R0 | Speaker mask |
| R1 | Validity mask |
| All other registers preserved | |
Use
This call provides a means for software to determine which speakers may be available on a given display. Normally this information is determined by reading the displays EDID.
Because the speaker mask is an optional part of the EDID, two values are returned: the speaker mask as reported from the monitor (in R0), and a validity mask (in R1) which indicates which bits of R0 have been specified. The following table can be used as a guide to determine whether a given speaker is available or not:
| Speaker mask bit value | Validity mask bit value | Interpretation |
|---|---|---|
| 0 | 0 | Monitor did not provide information – speaker may or may not be present |
| 0 | 1 | Speaker is not present |
| 1 | 0 | Reserved |
| 1 | 1 | Speaker is present |
Notes
Bit allocation in the two words follows the same scheme as the CEA 861 speaker allocation data block:
| Bit | Interpretation |
|---|---|
| 0 | Front Left & Front Right |
| 1 | LFE |
| 2 | Front Center |
| 3 | Rear Left & Rear Right |
| 4 | Rear Center |
| 5 | Front Left Center & Front Right Center |
| 6 | Rear Left Center & Rear Right Center |
| 7+ | Reserved |
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