source: bootcd/isolinux/syslinux-6.03/core/font.c

/* ----------------------------------------------------------------------- *
 *
 *   Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
 *   Copyright 2013 Intel Corporation
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

/*
 *
 * font.c
 *
 * VGA font handling code
 *
 */

#include <syslinux/firmware.h>
#include <syslinux/video.h>
#include <sys/io.h>
#include <stdio.h>
#include <fs.h>

#include "bios.h"
#include "graphics.h"
#include "core.h"

__export uint8_t UserFont = 0;          /* Using a user-specified font */

__export __lowmem char fontbuf[8192];

uint16_t GXPixCols = 1;         /* Graphics mode pixel columns */
uint16_t GXPixRows = 1;         /* Graphics mode pixel rows */

/*
 * loadfont:    Load a .psf font file and install it onto the VGA console
 *              (if we're not on a VGA screen then ignore.)
 */
__export void loadfont(const char *filename)
{
        struct psfheader {
                uint16_t magic;
                uint8_t mode;
                uint8_t height;
        } hdr;
        FILE *f;

        f = fopen(filename, "r");
        if (!f)
                return;

        /* Read header */
        if (_fread(&hdr, sizeof hdr, f) != sizeof hdr)
                goto fail;

        /* Magic number */
        if (hdr.magic != 0x0436)
                goto fail;

        /* File mode: font modes 0-5 supported */
        if (hdr.mode > 5)
                goto fail;

        /* VGA minimum/maximum */
        if (hdr.height < 2 || hdr.height > 32)
                goto fail;

        /* Load the actual font into the font buffer. */
        memset(fontbuf, 0, 256*32);
        if (_fread(fontbuf, 256*hdr.height, f) != 256*hdr.height)
            goto fail;

        /* Loaded OK */
        VGAFontSize = hdr.height;
        UserFont = 1;           /* Set font flag */
        use_font();

fail:
        fclose(f);
}

/*
 * use_font:
 *      This routine activates whatever font happens to be in the
 *      vgafontbuf, and updates the bios_adjust_screen data.
 *      Must be called with CS = DS
 */
void use_font(void)
{
        com32sys_t ireg, oreg;
        uint8_t bytes = VGAFontSize;

        /* Nonstandard mode? */
        if (UsingVGA & ~0x3)
                syslinux_force_text_mode();

        memset(&ireg, 0, sizeof(ireg));

        ireg.es = SEG(fontbuf);
        ireg.ebp.w[0] = OFFS(fontbuf); /* ES:BP -> font */

        /* Are we using a user-specified font? */
        if (UserFont & 0x1) {
                /* Are we in graphics mode? */
                if (UsingVGA & 0x1) {
                        uint8_t rows;

                        rows = GXPixRows / bytes;
                        VidRows = rows - 1;

                        /* Set user character table */
                        ireg.eax.w[0] = 0x1121;
                        ireg.ebx.b[0] = 0;
                        ireg.ecx.b[0] = bytes; /* bytes/character */
                        ireg.edx.b[0] = rows;

                        __intcall(0x10, &ireg, &oreg);

                        /* 8 pixels/character */
                        VidCols = ((GXPixCols >> 3) - 1);

                        /* No need to call bios_adjust_screen */
                        return;
                } else {
                        ireg.eax.w[0] = 0x1110; /* Load into VGA RAM */
                        ireg.ebx.b[0] = 0;
                        ireg.ebx.b[1] = bytes; /* bytes/character */
                        ireg.ecx.w[0] = 256;
                        ireg.edx.w[0] = 0;

                        __intcall(0x10, &ireg, &oreg);

                        memset(&ireg, 0, sizeof(ireg));
                        ireg.ebx.b[0] = 0;
                        ireg.eax.w[0] = 0x1103; /* Select page 0 */
                        __intcall(0x10, &ireg, NULL);
                }

        }

        bios_adjust_screen();
}

/*
 * bios_adjust_screen: Set the internal variables associated with the screen size.
 *              This is a subroutine in case we're loading a custom font.
 */
void bios_adjust_screen(void)
{
        com32sys_t ireg, oreg;
        volatile uint8_t *vidrows = (volatile uint8_t *)BIOS_vidrows;
        uint8_t rows, cols;

        memset(&ireg, 0, sizeof(ireg));

        rows = *vidrows;
        if (!rows) {
                /*
                 * No vidrows in BIOS, assume 25.
                 * (Remember: vidrows == rows-1)
                 */
                rows = 24;
        }

        VidRows = rows;

        ireg.eax.b[1] = 0x0f;   /* Read video state */
        __intcall(0x10, &ireg, &oreg);
        cols = oreg.eax.b[1];

        VidCols = --cols;       /* Store count-1 (same as rows) */
}

void adjust_screen(void)
{
        if (firmware->adjust_screen)
                firmware->adjust_screen();
}

void pm_adjust_screen(com32sys_t *regs __unused)
{
        adjust_screen();
}

void pm_userfont(com32sys_t *regs)
{
        regs->es = SEG(fontbuf);
        regs->ebx.w[0] = OFFS(fontbuf);
}