drivers/vga_set_mode.c

   1 /*
   2  * $Id$
   3  * $Source$
   4  *
   5  *  by
   6  *  Steve M. Gehlbach <steve@kesa.com>
   7  *
   8  *  These routines set graphics mode and alpha mode
   9  *  for switching back and forth.
  10  *
  11  *  Register settings are
  12  *  more or less as follows:
  13  *
  14  *  Register             Graphics      Alpha
  15  *                       16 color
  16  *  ------------------------------------------------
  17  *  GDC_MODE              0x00          0x10
  18  *  GDC_MISC              0x05          0x0e
  19  *  SEQ_MEMORY_MODE       0x06          0x02
  20  *  SEQ_PLANE_WRITE       0x0f          0x03
  21  *  CRTC_CURSOR_START     0x20          0x00
  22  *  CRTC_CURSOR_END       0x00          CHAR_HEIGHT-1
  23  *  CRTC_MODE             0xe3          0xa3
  24  *  CRTC_MAX_SCAN         0x40          0x40 | CHAR_HEIGHT-1
  25  *  ATC_MODE              0x01          0x0c
  26  *
  27  */
  28
  29 #include "asm/io.h"
  30 #include "vga.h"
  31
  32 void vga_set_gmode (void) {
  33         u8 byte;
  34
  35         byte = read_att_b(ATC_MODE) & ~0x0f;
  36         write_att(byte|0x1, ATC_MODE);
  37 //
  38 // display is off at this point
  39
  40         byte = read_seq_b(SEQ_PLANE_WRITE) & ~0xf;
  41         write_seq(byte|0xf,SEQ_PLANE_WRITE); // all planes
  42         byte = read_seq_b(SEQ_MEMORY_MODE);
  43         write_seq(byte|4,SEQ_MEMORY_MODE);
  44
  45         byte = read_gra_b(GDC_MODE) & ~0x10;
  46         write_gra(byte,GDC_MODE);
  47         write_gra(0x05, GDC_MISC);
  48
  49         write_crtc(0x20, CRTC_CURSOR_START);
  50         write_crtc(0x00, CRTC_CURSOR_END);
  51         byte = read_crtc_b(CRTC_MODE) & ~0xe0;
  52         write_crtc(byte|0xe0, CRTC_MODE);
  53         byte = read_crtc_b(CRTC_MAX_SCAN) & ~0x01f;
  54         write_crtc(byte, CRTC_MAX_SCAN);
  55
  56         byte = inb(MIS_R); // get 3c2 value by reading 3cc
  57         outb(byte & ~0xc,MIS_W); // clear last bits to set 25Mhz clock and low page
  58
  59
  60 // turn on display, disable access to attr palette
  61         inb(IS1_RC);
  62         outb(0x20, ATT_IW);
  63 }
  64
  65 void vga_set_amode (void) {
  66         u8 byte;
  67         write_att(0x0c, ATC_MODE);
  68
  69         //reset palette to normal in the case it was changed
  70         write_att(0x0, ATC_COLOR_PAGE);
  71 //
  72 // display is off at this point
  73
  74         write_seq(0x3,SEQ_PLANE_WRITE); // planes 0 & 1
  75         byte = read_seq_b(SEQ_MEMORY_MODE) & ~0x04;
  76         write_seq(byte,SEQ_MEMORY_MODE);
  77
  78         byte = read_gra_b(GDC_MODE) & ~0x60;
  79         write_gra(byte|0x10,GDC_MODE);
  80
  81         write_gra(0x0e, GDC_MISC);
  82
  83         write_crtc(0x00, CRTC_CURSOR_START);
  84         write_crtc(CHAR_HEIGHT-1, CRTC_CURSOR_END);
  85
  86         byte = read_crtc_b(CRTC_MODE) & ~0xe0;
  87         write_crtc(byte|0xa0, CRTC_MODE);
  88         byte = read_crtc_b(CRTC_MAX_SCAN) & ~0x01f;
  89         write_crtc(byte | (CHAR_HEIGHT-1), CRTC_MAX_SCAN);
  90
  91
  92 // turn on display, disable access to attr palette
  93         inb(IS1_RC);
  94         outb(0x20, ATT_IW);
  95 }
  96
  97 /*
  98  * by Steve M. Gehlbach, Ph.D. <steve@kesa.com>
  99  *
 100  * vga_font_load loads a font into font memory.  It
 101  * assumes alpha mode has been set.
 102  *
 103  * The font load code follows technique used
 104  * in the tiara project, which came from
 105  * the Universal Talkware Boot Loader,
 106  * http://www.talkware.net.
 107  */
 108
 109 void vga_font_load(unsigned char *vidmem, const unsigned char *font, int height, int num_chars) {
 110
 111 /* Note: the font table is 'height' long but the font storage area
 112  * is 32 bytes long.
 113  */
 114
 115         int i,j;
 116         u8 byte;
 117
 118         // set sequencer map 2, odd/even off
 119         byte = read_seq_b(SEQ_PLANE_WRITE) & ~0xf;
 120         write_seq(byte|4,SEQ_PLANE_WRITE);
 121         byte = read_seq_b(SEQ_MEMORY_MODE);
 122         write_seq(byte|4,SEQ_MEMORY_MODE);
 123
 124         // select graphics map 2, odd/even off, map starts at 0xa0000
 125         write_gra(2,GDC_PLANE_READ);
 126         byte = read_gra_b(GDC_MODE) & ~0x10;
 127         write_gra(byte,GDC_MODE);
 128         write_gra(0,GDC_MISC);
 129
 130         for (i = 0 ; i < num_chars ; i++) {
 131                 for (j = 0 ; j < height ; j++) {
 132                         vidmem[i*32+j] = font[i*16+j];
 133                 }
 134         }
 135
 136         // set sequencer back to maps 0,1, odd/even on
 137         byte = read_seq_b(SEQ_PLANE_WRITE) & ~0xf;
 138         write_seq(byte|3,SEQ_PLANE_WRITE);
 139         byte = read_seq_b(SEQ_MEMORY_MODE) & ~0x4;
 140         write_seq(byte,SEQ_MEMORY_MODE);
 141
 142         // select graphics back to map 0,1, odd/even on
 143         write_gra(0,GDC_PLANE_READ);
 144         byte = read_gra_b(GDC_MODE);
 145         write_gra(byte|0x10,GDC_MODE);
 146         write_gra(0xe,GDC_MISC);
 147
 148 }