video_subr.c

Go to the documentation of this file.

/*
 *
 * modified from linuxbios code
 * by Cai Qiang <rimy2000@hotmail.com>
 *
 */

#include "stddef.h"
#include "string.h"
#include <gpxe/io.h>
#include "console.h"
#include <gpxe/init.h>
#include "vga.h"

struct console_driver vga_console;

static char *vidmem;            /* The video buffer */
static int video_line, video_col;

#define VIDBUFFER 0xB8000       

static void memsetw(void *s, int c, unsigned int n)
{
        unsigned int i;
        u16 *ss = (u16 *) s;

        for (i = 0; i < n; i++) {
                ss[i] = ( u16 ) c;
        }
}

static void video_init(void)
{
        static int inited=0;

        vidmem = (char *)phys_to_virt(VIDBUFFER);

        if (!inited) {
                video_line = 0;
                video_col = 0;
        
                memsetw(vidmem, VGA_ATTR_CLR_WHT, 2*1024); //

                inited=1;
        }
}

static void video_scroll(void)
{
        int i;

        memcpy(vidmem, vidmem + COLS * 2, (LINES - 1) * COLS * 2);
        for (i = (LINES - 1) * COLS * 2; i < LINES * COLS * 2; i += 2)
                vidmem[i] = ' ';
}

static void vga_putc(int 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);
}

struct console_driver vga_console __console_driver = {
        .putchar = vga_putc,
        .disabled = 1,
};

struct init_fn video_init_fn __init_fn ( INIT_EARLY ) = {
        .initialise = video_init,
};