GA_CRTCInfoFlagsType

Declaration

typedef enum {
gaInterlaced = 0x01,
gaDoubleScan = 0x02,
gaTripleScan = 0x04,
gaHSyncNeg = 0x08,
gaVSyncNeg = 0x10
} GA_CRTCInfoFlagsType

Prototype In

snap/graphics.h

Description

Definitions for flags member of the GA_CRTCInfo structure. These flags define the different flags required to complete a mode set with refresh rate control enabled.

The gaInterlaced flag is used to determine whether the mode programmed into the hardware is interlaced or non-interlaced. The CRTC timings passed in will be identical for both interlaced and non-interlaced modes, and it is up to the graphics driver to perform any necessary scaling between the hardware values and the normalized CRTC values in interlaced modes. Note that you must check the gaHaveInterlaced bit in the GA_modeInfo structure to determine if interlaced mode is supported before attempting to initialise an interlaced mode.

The gaDoubleScan flag is used to determine whether the mode programmed into the hardware is double scanned or not. When double scanning is specified, the vertical CRTC values passed in will be double what the real vertical resolution will be. Double scanning is used to implement the 200, 240 and 300 line graphics modes on modern controllers. Note that you must check the gaHaveDoubleScan bit in the GA_modeInfo structure to determine if double scan mode is supported by the hardware in that display mode. Note also that all modes with vertical resolutions below 300 scanline modes require the double scanning to be enabled, and modes between 300 and 400 scanlines can usually look better if it is enabled.

The gaHSyncNeg flag is used to determine if the horizontal sync polority should be set to a negative sync (gaHSyncNeg is set) or positive sync (gaHSyncNeg is not set).

The gaVSyncNeg flag is used to determine if the vertical sync polority should be set to a negative sync (gaVSyncNeg is set) or positive sync (gaVSyncNeg is not set).

Members

gaInterlaced | Enable interlaced mode
gaDoubleScan | Enable double scanned mode
gaTripleScan | Enable triple scanned mode
gaHSyncNeg | Horizontal sync is negative
gaVSyncNeg | Vertical sync is negative

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