core/font.c

   1 /*
   2  * -----------------------------------------------------------------------
   3  *
   4  *   Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
   5  *
   6  *   This program is free software; you can redistribute it and/or modify
   7  *   it under the terms of the GNU General Public License as published by
   8  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   9  *   Boston MA 02111-1307, USA; either version 2 of the License, or
  10  *   (at your option) any later version; incorporated herein by reference.
  11  *
  12  * -----------------------------------------------------------------------
  13  *
  14  *
  15  * font.c
  16  *
  17  * VGA font handling code
  18  *
  19  */
  20
  21 #include <sys/io.h>
  22 #include <stdio.h>
  23 #include <fs.h>
  24
  25 #include "bios.h"
  26 #include "graphics.h"
  27 #include "core.h"
  28
  29 __export uint8_t UserFont = 0;          /* Using a user-specified font */
  30
  31 __export __lowmem char fontbuf[8192];
  32
  33 uint16_t GXPixCols = 1;         /* Graphics mode pixel columns */
  34 uint16_t GXPixRows = 1;         /* Graphics mode pixel rows */
  35
  36 /*
  37  * loadfont:    Load a .psf font file and install it onto the VGA console
  38  *              (if we're not on a VGA screen then ignore.)
  39  */
  40 __export void loadfont(const char *filename)
  41 {
  42         struct psfheader {
  43                 uint16_t magic;
  44                 uint8_t mode;
  45                 uint8_t height;
  46         } hdr;
  47         FILE *f;
  48         char *p;
  49         int i;
  50
  51         f = fopen(filename, "r");
  52         if (!f)
  53                 return;
  54
  55         /* Read header */
  56         if (_fread(&hdr, sizeof hdr, f) != sizeof hdr)
  57                 goto fail;
  58
  59         /* Magic number */
  60         if (hdr.magic != 0x0436)
  61                 goto fail;
  62
  63         /* File mode: font modes 0-5 supported */
  64         if (hdr.mode > 5)
  65                 goto fail;
  66
  67         /* VGA minimum/maximum */
  68         if (hdr.height < 2 || hdr.height > 32)
  69                 goto fail;
  70
  71         /* Load the actual font into the font buffer. */
  72         memset(fontbuf, 0, 256*32);
  73
  74         p = fontbuf;
  75         for (i = 0; i < 256; i++) {
  76                 if (_fread(p, hdr.height, f) != hdr.height)
  77                         goto fail;
  78                 p += 32;
  79         }
  80
  81         /* Loaded OK */
  82         VGAFontSize = hdr.height;
  83         UserFont = 1;           /* Set font flag */
  84         use_font();
  85
  86 fail:
  87         fclose(f);
  88 }
  89
  90 /*
  91  * use_font:
  92  *      This routine activates whatever font happens to be in the
  93  *      vgafontbuf, and updates the adjust_screen data.
  94  *      Must be called with CS = DS
  95  */
  96 void use_font(void)
  97 {
  98         com32sys_t ireg, oreg;
  99         uint8_t bytes = VGAFontSize;
 100
 101         /* Nonstandard mode? */
 102         if (UsingVGA & ~0x3)
 103                 syslinux_force_text_mode();
 104
 105         memset(&ireg, 0, sizeof(ireg));
 106
 107         ireg.es = SEG(fontbuf);
 108         ireg.ebp.w[0] = OFFS(fontbuf); /* ES:BP -> font */
 109
 110         /* Are we using a user-specified font? */
 111         if (UserFont & 0x1) {
 112                 /* Are we in graphics mode? */
 113                 if (UsingVGA & 0x1) {
 114                         uint8_t rows;
 115
 116                         rows = GXPixRows / bytes;
 117                         VidRows = rows - 1;
 118
 119                         /* Set user character table */
 120                         ireg.eax.w[0] = 0x1121;
 121                         ireg.ebx.b[0] = 0;
 122                         ireg.ecx.b[0] = bytes; /* bytes/character */
 123                         ireg.edx.b[0] = rows;
 124
 125                         __intcall(0x10, &ireg, &oreg);
 126
 127                         /* 8 pixels/character */
 128                         VidCols = ((GXPixCols >> 3) - 1);
 129
 130                         /* No need to call adjust_screen */
 131                         return;
 132                 } else {
 133                         ireg.eax.w[0] = 0x1110; /* Load into VGA RAM */
 134                         ireg.ebx.b[0] = 0;
 135                         ireg.ebx.b[1] = bytes; /* bytes/character */
 136                         ireg.ecx.w[0] = 256;
 137                         ireg.edx.w[0] = 0;
 138
 139                         __intcall(0x10, &ireg, &oreg);
 140
 141                         ireg.ebx.b[0] = 0;
 142                         ireg.eax.w[0] = 0x1103; /* Select page 0 */
 143                         __intcall(0x10, &ireg, NULL);
 144                 }
 145         }
 146
 147         adjust_screen();
 148 }
 149
 150 /*
 151  * adjust_screen: Set the internal variables associated with the screen size.
 152  *              This is a subroutine in case we're loading a custom font.
 153  */
 154 void adjust_screen(void)
 155 {
 156         com32sys_t ireg, oreg;
 157         volatile uint8_t *vidrows = (volatile uint8_t *)BIOS_vidrows;
 158         uint8_t rows, cols;
 159
 160         rows = *vidrows;
 161         if (!rows) {
 162                 /*
 163                  * No vidrows in BIOS, assume 25.
 164                  * (Remember: vidrows == rows-1)
 165                  */
 166                 rows = 24;
 167         }
 168
 169         VidRows = rows;
 170
 171         ireg.eax.b[1] = 0x0f;   /* Read video state */
 172         __intcall(0x10, &ireg, &oreg);
 173         cols = oreg.eax.b[1];
 174
 175         VidCols = --cols;       /* Store count-1 (same as rows) */
 176 }
 177
 178 void pm_adjust_screen(com32sys_t *regs __unused)
 179 {
 180         adjust_screen();
 181 }
 182
 183 void pm_userfont(com32sys_t *regs)
 184 {
 185         regs->es = SEG(fontbuf);
 186         regs->ebx.w[0] = OFFS(fontbuf);
 187 }