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#include "colours.h"
#define COLS (80 * 2) // 2 bytes per char
#define ROWS 25
#define FRAME_SIZE (ROWS * COLS)
char *video_ram = (char *) 0xB8000;
int cursor_pos = 0;
int char_attribute_byte = 0x07;
void vga_clear_screen()
{
for (int i = 0; i < FRAME_SIZE; i = i + 2)
{
video_ram[i] = ' ';
video_ram[i + 1] = char_attribute_byte;
};
cursor_pos = 0;
}
void vga_print(char *msg)
{
int j = 0;
while (msg[j] != '\0')
{
video_ram[cursor_pos++] = msg[j];
video_ram[cursor_pos++] = char_attribute_byte;
++j;
}
}
void vga_print_ln(char *msg)
{
vga_print(msg);
int current_line = cursor_pos / COLS;
cursor_pos = (current_line + 1) * COLS;
}
void vga_set_text_colour(int foreground, int background)
{
char_attribute_byte = (background << 4) | foreground;
}
void vga_print_raw(unsigned char byte)
{
video_ram[cursor_pos++] = byte;
video_ram[cursor_pos++] = char_attribute_byte;
}
// TODO - jump cursor to prev non 0 text char rather than reversing through whole array
void vga_backspace()
{
if (cursor_pos != 0)
{
video_ram[--cursor_pos] = char_attribute_byte;
video_ram[--cursor_pos] = 0;
}
}
void vga_newline()
{
int current_line = cursor_pos / COLS;
cursor_pos = (current_line + 1) * COLS;
}
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