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#include "video-vga.h"
#include "string.h"
#include "i386.h"
#define VGA_BASE 0xB8000
#define CRTC_PORT 0x3D4
#define VGA_WIDTH 80
#define VGA_HEIGHT 25
static size_t vga_row, vga_column;
static uint8_t vga_color;
static uint16_t *vga_buffer;
uint8_t vga_entry_color(enum vga_colors fg, enum vga_colors bg)
{
return fg | bg << 4;
}
uint16_t vga_entry(uint8_t uc, uint8_t color)
{
return (uint16_t) uc | (uint16_t) color << 8;
}
void vga_init(void)
{
size_t x, y;
size_t vga_char;
vga_row = 0, vga_column = 0;
vga_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
vga_char = vga_entry(' ', vga_color);
vga_buffer = (uint16_t *) VGA_BASE;
for(y = 0; y < VGA_HEIGHT; y++) {
for(x = 0; x < VGA_WIDTH; x++) {
const size_t index = y * VGA_WIDTH + x;
vga_buffer[index] = vga_char;
}
}
}
void vga_setcolor(uint8_t color)
{
vga_color = color;
}
void vga_scroll(size_t lines)
{
size_t count = (VGA_HEIGHT - lines) * VGA_WIDTH;
size_t vga_char = vga_entry(' ', vga_color);
memmove(vga_buffer, vga_buffer + VGA_WIDTH * lines, count * 2);
for(; count < (vga_row + 1) * VGA_WIDTH; count++)
vga_buffer[count] = vga_char;
}
void vga_putchar(char c)
{
uint16_t pos;
if(c == '\n') {
vga_column = 0;
if(++vga_row >= VGA_HEIGHT) {
vga_scroll(1);
vga_row--;
}
}
else {
const size_t index = vga_row * VGA_WIDTH + vga_column;
vga_buffer[index] = vga_entry(c, vga_color);
if(++vga_column >= VGA_WIDTH) {
vga_column = 0;
if(++vga_row >= VGA_HEIGHT) {
vga_scroll(1);
vga_row--;
}
}
}
/* Update cursor position */
pos = vga_row * VGA_WIDTH + vga_column;
outb(CRTC_PORT, 0x0E);
outb(CRTC_PORT+1, (uint8_t) ((pos >> 8) & 0xFF));
outb(CRTC_PORT, 0x0F);
outb(CRTC_PORT+1, (uint8_t) (pos & 0xFF));
}
void vga_write(const char *str, size_t size)
{
size_t i;
for(i = 0; i < size; i++)
vga_putchar(str[i]);
}
void vga_print(const char *str)
{
vga_write(str, strlen(str));
}
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