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Video

This header defines the interface for video (display) drivers. It allows high-level code to manipulate the display independently of the underlying hardware.

Functions

Section titled “Functions”

video_get_current_interface

Section titled “video_get_current_interface”

Get the video interface currently in use. This can be NULL if the program is being linked without a display driver.

video_interface_t const *video_get_current_interface(void)

video_get_current_mode_index

Section titled “video_get_current_mode_index”

Get the index of the current video mode. This can be -1 if there is no interface; however, if there is an interface, this is always >= 0.

int video_get_current_mode_index(void)

video_get_current_mode

Section titled “video_get_current_mode”

Get the a pointer to the current video mode’s definition.

video_mode_t const *video_get_current_mode(void)

video_update

Section titled “video_update”

Update the contents of the display from a framebuffer image. A combination of VIDEO_UPDATE_* flags can be specified to select the update method:

  • ENABLE_DMA allows the driver to copy using DMA, when applicable;
  • ATOMIC requires the driver to use an interrupt-less method. Returns true on success.

Update flags will be ignored if not applicable (e.g. ENABLE_DMA for a video interface that doesn’t support DMA) but will result in an error if applicable and the specified method fails (e.g. DMA transfer error).

This function is usually called with (x,y) = (0,0) and a contiguous framebuffer whose size is the video mode size. Specifying images with other sizes, positions and strides is allowed only when they result in data transfers that are byte-aligned. DMA support is only guaranteed for contiguous input and output. The implied rectangle must be in-bounds.

bool video_update(int x, int y, image_t const *fb, int flags)

Macros

Section titled “Macros”

VIDEO_UPDATE_NONE

Section titled “VIDEO_UPDATE_NONE”

Flags for the update function of the interface.

#define VIDEO_UPDATE_NONE 0x00
#define VIDEO_UPDATE_ENABLE_DMA 0x01
#define VIDEO_UPDATE_ATOMIC 0x02
#define VIDEO_UPDATE_FOREIGN_WORLD 0x04

Types

Section titled “Types”
typedef struct
{
  /* Mode size */ uint16_t width;
  uint16_t height;
  /* Pixel format */ int16_t format;
  /* Refresh frequency, -1 if unknown */ int16_t freq;
}
video_mode_t

Video driver interface.

typedef struct
{
  /* Associated driver (NULL if there's none). */ gint_driver_t const *driver;
  /* List of modes (terminated by an all-0 element). The first mode is the default mode and it should always be available. */ video_mode_t const *modes;
  /* Get current video mode. */ uint (*mode_get)(void);
  /* Set a video mode. */ bool (*mode_set)(uint id);
  /* Minimum and maximum brightness settings. */ int brightness_min;
  int brightness_max;
  /* Set a brightness setting. */ bool (*brightness_set)(int setting);
  /* Implements video_update();
  bounds are checked befoer calling. */ bool (*update)(int x, int y, image_t const *framebuffer, int flags);
}
video_interface_t

Source

Section titled “Source”