VGA library (libvga)
Contents
- General information
- Mode Adjustment Flags
- Structures
- Low-Level Interface (Hardware Abstraction Layer)
- Memory and Register Access
- Color Map Management
- VGA Handle Management
- High-Level Interface
- VGA Register and Mode Management
- VGA State Management
- VGA Configuration
- Using libvga
General information
libvga is designed to interface with VGA-compatible display hardware. This library provides both low-level hardware
access and high-level functionality to manage VGA display settings, modes, and memory.
Mode Adjustment Flags
Adjustment flags are used to modify the behavior of the VGA display modes.
VGA_HSYNCP: Set for HSync positive polarity.
VGA_VSYNCP: Set for VSync positive polarity.
VGA_CLKDIV: Indicates the pixel clock is divided by 2.
VGA_DBLSCAN: Enables double scanning.
VGA_INTERLACE: Activates interlace mode.
Structures
vga_cfg_t- Holds the configuration for a VGA mode, including pixel clock, horizontal and vertical timings, and mode adjustment flags.
typedef struct {
/* Pixel clock */
unsigned int clkidx; /* Pixel clock source index */
unsigned int clk; /* Pixel clock frequency (kHz) */
/* Horizontal timings */
unsigned int hres; /* Horizontal resolution */
unsigned int hsyncs; /* Horizontal sync start */
unsigned int hsynce; /* Horizontal sync end */
unsigned int htotal; /* Horizontal total pixels */
/* Vertical timings */
unsigned int vres; /* Vertical resolution */
unsigned int vsyncs; /* Vertical sync start */
unsigned int vsynce; /* Vertical sync end */
unsigned int vtotal; /* Vertical total lines */
/* Mode adjustments */
unsigned char flags; /* Mode adjustment flags */
} vga_cfg_t;
vga_state_t- Represents the state of the VGA, including various registers, color map, text, and font data.
typedef struct {
unsigned char mr; /* Miscellaneous register */
unsigned char cr[25]; /* CRT controller registers */
unsigned char sr[5]; /* Sequencer registers */
unsigned char gr[9]; /* Graphics controller registers */
unsigned char ar[21]; /* Attribute controller registers */
unsigned char *cmap; /* Color map */
unsigned char *text; /* Plane 0 and 1 text */
unsigned char *font1; /* Plane 2 font */
unsigned char *font2; /* Plane 3 font */
} vga_state_t;
Low-Level Interface (Hardware Abstraction Layer)
Memory and Register Access
vgahw_mem- Returns the mapped VGA memory address.
void *vgahw_mem(void *hwctx)
vgahw_status- Reads from the input status register.
unsigned char vgahw_status(void *hwctx)
vgahw_readfcr- Read operations for the feature control register.
unsigned char vgahw_readfcr(void *hwctx)
vgahw_writefcr- Write operations for the feature control register.
void vgahw_writefcr(void *hwctx, unsigned char val)
vgahw_readmisc- Read operations for the miscellaneous register.
unsigned char vgahw_readmisc(void *hwctx)
vgahw_readmisc- Write operations for the miscellaneous register.
void vgahw_writemisc(void *hwctx, unsigned char val)
vgahw_readcrtc- Read operations for CRT controller registers.
unsigned char vgahw_readcrtc(void *hwctx, unsigned char reg)
vgahw_writecrtc- Write operations for CRT controller registers.
void vgahw_writecrtc(void *hwctx, unsigned char reg, unsigned char val)
vgahw_readseq- Read operations for sequencer registers.
unsigned char vgahw_readseq(void *hwctx, unsigned char reg)
vgahw_writeseq- Write operations for sequencer registers.
void vgahw_writeseq(void *hwctx, unsigned char reg, unsigned char val)
vgahw_readgfx- Read operations for graphics controller registers.
unsigned char vgahw_readgfx(void *hwctx, unsigned char reg)
vgahw_writegfx- Write operations for graphics controller registers.
void vgahw_writegfx(void *hwctx, unsigned char reg, unsigned char val)
vgahw_readattr- Read operations for attribute controller registers.
unsigned char vgahw_readattr(void *hwctx, unsigned char reg)
vgahw_writeattr- Write operations for attribute controller registers.
void vgahw_writeattr(void *hwctx, unsigned char reg, unsigned char val)
vgahw_readdac- Read operations for DAC controller registers.
unsigned char vgahw_readdac(void *hwctx, unsigned char reg)
vgahw_writedac- Write operations for DAC controller registers.
void vgahw_writedac(void *hwctx, unsigned char reg, unsigned char val)
Color Map Management
vgahw_enablecmap- Enables the color map.
void vgahw_enablecmap(void *hwctx)
vgahw_disablecmap- Disables the color map.
void vgahw_disablecmap(void *hwctx)
VGA Handle Management
vgahw_init- Initializes the VGA handle.
int vgahw_init(void *hwctx)
vgahw_done- Destroys the VGA handle.
void vgahw_done(void *hwctx)
High-Level Interface
VGA Register and Mode Management
vga_lock- Lock CRTC[0-7] registers.
void vga_lock(void *hwctx)
vga_unlock- Unlock CRTC[0-7] registers.
void vga_unlock(void *hwctx)
vga_mlock- Protect/release VGA registers and memory during mode switch.
void vga_mlock(void *hwctx)
vga_munlock- Protect/release VGA registers and memory during mode switch.
void vga_munlock(void *hwctx)
vga_blank- Blanks the screen.
void vga_blank(void *hwctx)
vga_unblank- Un blanks the screen.
void vga_unblank(void *hwctx)
VGA State Management
vga_savemode- Save the VGA mode.
void vga_savemode(void *hwctx, vga_state_t *state)
vga_restoremode- Restore the VGA mode.
void vga_restoremode(void *hwctx, vga_state_t *state)
vga_savecmap- Save the VGA color map.
void vga_savecmap(void *hwctx, vga_state_t *state)
vga_restorecmap- Restore the VGA color map.
void vga_restorecmap(void *hwctx, vga_state_t *state)
vga_savetext- Save VGA fonts and text.
void vga_savetext(void *hwctx, vga_state_t *state)
vga_restoretext- Restore VGA fonts and text.
void vga_restoretext(void *hwctx, vga_state_t *state)
vga_save- Save all VGA settings.
void vga_save(void *hwctx, vga_state_t *state)
vga_restore- Restore all VGA settings.
void vga_restore(void *hwctx, vga_state_t *state)
VGA Configuration
vga_initstate- Initializes the VGA state for a given mode configuration.
void vga_initstate(vga_cfg_t *cfg, vga_state_t *state)
Using libvga
To use functions provided by libvga please add the library to the LIBS variable in Makefile and include the
required header file.