mirrors/cosmopolitan
1
0
Fork 0
mirror of https://github.com/jart/cosmopolitan.git synced 2025-07-27 04:50:28 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Bare metal VGA: minor improvements (#608)

Browse source
This commit is contained in:
tkchia 2022-09-10 19:28:28 +08:00 • committed by GitHub
parent 155b378a39
commit bae7367774
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
3 changed files with 79 additions and 101 deletions
Download patch file Download diff file Expand all files Collapse all files

16
libc/vga/writev-vga.c
View file

@ -58,15 +58,23 @@ ssize_t sys_writev_vga(struct Fd *fd, const struct iovec *iov, int iovlen) {
__attribute__((__constructor__)) static textstartup void _vga_init(void) {
void * const vid_buf = (void *)(BANE + 0xb8000ull);
/* Get the initial cursor position from the BIOS data area. */
/*
* Get the initial cursor position from the BIOS data area. Also get
* the height (in scan lines) of each character; this is used to set the
* cursor shape.
*/
typedef struct {
unsigned char col, row;
} bios_curs_pos_t;
bios_curs_pos_t pos = *(bios_curs_pos_t *)(BANE + 0x0450ull);
uint8_t chr_ht = *(uint8_t *)(BANE + 0x0485ull),
chr_ht_hi = *(uint8_t *)(BANE + 0x0486ull);
if (chr_ht_hi != 0 || chr_ht > 32)
chr_ht = 32;
/*
* Initialize our tty structure from the current screen contents & current
* cursor position.
* Initialize our tty structure from the current screen contents, current
* cursor position, & character height.
*/
_StartTty(&vga_tty, VGA_TTY_HEIGHT, VGA_TTY_WIDTH, pos.row, pos.col,
vid_buf, vga_wcs);
chr_ht, vid_buf, vga_wcs);
}