Entry | |
---|---|
R4 | Bits 0-23: 8 (reason code) |
Bits 24-31: Display number |
Exit | |
---|---|
R0 | Feature flags: |
Bit 0: Supports hardware scroll | |
Bit 1: Supports hardware pointer | |
Bit 2: Supports interlace with progressive framestore | |
Bit 3: Uses seperate framestore | |
Bit 4: No VSyncs generated | |
R1 | Mask of supported pixel formats: |
Bit 0: 1bpp palettised | |
Bit 1: 2bpp palettised | |
Bit 2: 4bpp palettised | |
Bit 3: 8bpp palettised | |
Bit 4: 16bpp RGB | |
Bit 5: 32bpp RGB | |
R2 | Display buffer alignment requirement in bytes (power of 2) |
R4 | 0 |
- | All other registers preserved |
The kernel issues this to determine the available features of a driver. The appropriate driver should respond by setting R4 to 0 to claim the call, and setting R0-R2 to the appropriate values.
The default claimant of this call is the kernel. If the call is left unclaimed, and the call was for display 0, the kernel will claim it by setting R4 to 0 and obtain the necessary information by calling HAL_VideoFeatures, HAL_VideoPixelFormats, and HAL_VideoBufferAlignment.