A poorly written OS for the x86 arch. (WIP)
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eOS/drivers/vga.c

67 lines
1.4 KiB

// VGA Graphics Library
#include "../kernel/io.h"
// VGA base address: 0xb8000
// Charpos = 0xb8000 + 2(row*80 + col)
// Memory
#define VIDEO_MEM (char*)0xb8000
#define VIDEO_MEM_MAX (char*)0xb8fa0
// Global
static unsigned int cursor_row = 0;
static unsigned int cursor_col = 0;
/*
VGA & Memory Functions
*/
char* get_vga_charpos_pointer(unsigned int col, unsigned int row) {
return (char*)(VIDEO_MEM + 2*((row*80) + col));
}
void writechar(char c, unsigned int col, unsigned int row, int attribute_byte) {
char* mem = get_vga_charpos_pointer(col, row);
*mem = c; // Write the character
*(mem+1) = attribute_byte; // Write the attribute_byte
}
/*
Graphics Functions
*/
void clear_screen() {
// Make all the characters spaces
for( char* c = VIDEO_MEM; c <= VIDEO_MEM_MAX; c += 2 )
*c = 0x20;
}
void disable_vga_cursor() {
port_outb(0x0a, 0x3d4);
port_outb(0x20, 0x3d5);
}
/*
General Printing Functions
*/
void set_cursor_pos(unsigned int x, unsigned int y) {
cursor_col = x;
cursor_row = y;
}
void print(char* str, int attribute_byte) {
for( char* c = str; *c != '\0'; c++ )
writechar(*c, (unsigned int)(c - str) + cursor_col, cursor_row, attribute_byte);
}
void println(char* str, int attribute_byte) {
print(str, attribute_byte);
cursor_row++; // Increment to next y-pos (newline)
}
// VGA Initialization Function
void vga_init() {
disable_vga_cursor();
clear_screen();
}