void vga_set_gmode (void) {
u8 byte;
byte = read_att_b(ATC_MODE) & ~0x0f;
write_att(byte|0x1, ATC_MODE);
//
// display is off at this point
byte = read_seq_b(SEQ_PLANE_WRITE) & ~0xf;
write_seq(byte|0xf,SEQ_PLANE_WRITE); // all planes
byte = read_seq_b(SEQ_MEMORY_MODE);
write_seq(byte|4,SEQ_MEMORY_MODE);
byte = read_gra_b(GDC_MODE) & ~0x10;
write_gra(byte,GDC_MODE);
write_gra(0x05, GDC_MISC);
write_crtc(0x20, CRTC_CURSOR_START);
write_crtc(0x00, CRTC_CURSOR_END);
byte = read_crtc_b(CRTC_MODE) & ~0xe0;
write_crtc(byte|0xe0, CRTC_MODE);
byte = read_crtc_b(CRTC_MAX_SCAN) & ~0x01f;
write_crtc(byte, CRTC_MAX_SCAN);
byte = inb(MIS_R); // get 3c2 value by reading 3cc
outb(byte & ~0xc,MIS_W); // clear last bits to set 25Mhz clock and low page
// turn on display, disable access to attr palette
inb(IS1_RC);
outb(0x20, ATT_IW);
}
void vga_set_amode (void) {
u8 byte;
write_att(0x0c, ATC_MODE);
//reset palette to normal in the case it was changed
write_att(0x0, ATC_COLOR_PAGE);
//
// display is off at this point
write_seq(0x3,SEQ_PLANE_WRITE); // planes 0 & 1
byte = read_seq_b(SEQ_MEMORY_MODE) & ~0x04;
write_seq(byte,SEQ_MEMORY_MODE);
byte = read_gra_b(GDC_MODE) & ~0x60;
write_gra(byte|0x10,GDC_MODE);
write_gra(0x0e, GDC_MISC);
write_crtc(0x00, CRTC_CURSOR_START);
write_crtc(CHAR_HEIGHT-1, CRTC_CURSOR_END);
byte = read_crtc_b(CRTC_MODE) & ~0xe0;
write_crtc(byte|0xa0, CRTC_MODE);
byte = read_crtc_b(CRTC_MAX_SCAN) & ~0x01f;
write_crtc(byte | (CHAR_HEIGHT-1), CRTC_MAX_SCAN);
// turn on display, disable access to attr palette
inb(IS1_RC);
outb(0x20, ATT_IW);
}
void vga_putc(unsigned char byte)
{
if (byte == '\n') {
video_line++;
video_col = 0;
} else if (byte == '\r') {
video_col = 0;
} else if (byte == '\b') {
video_col--;
} else if (byte == '\t') {
video_col += 4;
} else if (byte == '\a') {
//beep
//beep(500);
} else {
vidmem[((video_col + (video_line *COLS)) * 2)] = byte;
vidmem[((video_col + (video_line *COLS)) * 2) +1] = VGA_ATTR_CLR_WHT;
video_col++;
}
if (video_col < 0) {
video_col = 0;
}
if (video_col >= COLS) {
video_line++;
video_col = 0;
}
if (video_line >= LINES) {
video_scroll();
video_line--;
}
// move the cursor
write_crtc((video_col + (video_line *COLS)) >> 8, CRTC_CURSOR_HI);
write_crtc((video_col + (video_line *COLS)) & 0x0ff, CRTC_CURSOR_LO);
}
