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vga.c
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vga.c
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/****************************************************************************
* *
* Third Year Project *
* *
* An IBM PC Emulator *
* For Unix and X Windows *
* *
* By David Hedley *
* *
* *
* This program is Copyrighted. Consult the file COPYRIGHT for more details *
* *
****************************************************************************/
/* This is VGA.C It contains stuff about the VGA BIOS */
#include "global.h"
#include <stdio.h>
#include <string.h>
#include "vga.h"
#include "bios.h"
#include "cpu.h"
#include "vgahard.h"
#include "video.h"
#include "hardware.h"
#define MAXPAGES 8
#define VIDEOFUNCTIONALITY 0x2000
static BYTE *data_segment; /* pointer to 0040:0000 */
static BYTE *screen_mem; /* pointer to screen memory */
#define MAXMODE (sizeof defaults/sizeof defaults[0])
static struct
{
int cs, ce;
int sx, sy;
int colours;
int pages;
int base;
int text;
} defaults[] =
{
{ 6, 7, 40, 25, 16, 8, 0xb800, TRUE }, /* Mode 0x00 */
{ 6, 7, 40, 25, 16, 8, 0xb800, TRUE }, /* Mode 0x01 */
{ 6, 7, 80, 25, 16, 8, 0xb800, TRUE }, /* Mode 0x02 */
{ 6, 7, 80, 25, 16, 8, 0xb800, TRUE }, /* Mode 0x03 */
{ 0, 0, 320, 200, 4, 4, 0xb800, FALSE }, /* Mode 0x04 */
{ 0, 0, 320, 200, 4, 4, 0xb800, FALSE }, /* Mode 0x05 */
{ 0, 0, 640, 200, 2, 4, 0xb800, FALSE }, /* Mode 0x06 */
{ 11, 12, 80, 25, 2, 8, 0xb000, TRUE }, /* Mode 0x07 */
{ 0, 0, 0, 0, 0, 0, 0, FALSE }, /* Mode 0x08 */
{ 0, 0, 0, 0, 0, 0, 0, FALSE }, /* Mode 0x09 */
{ 0, 0, 0, 0, 0, 0, 0, FALSE }, /* Mode 0x0a */
{ 0, 0, 0, 0, 0, 0, 0, FALSE }, /* Mode 0x0b */
{ 0, 0, 0, 0, 0, 0, 0, FALSE }, /* Mode 0x0c */
{ 0, 0, 320, 200, 16, 8, 0xa000, FALSE },/* Mode 0x0d */
{ 0, 0, 640, 200, 16, 4, 0xa000, FALSE },/* Mode 0x0e */
{ 0, 0, 640, 350, 2, 2, 0xa000, FALSE }, /* Mode 0x0f */
{ 0, 0, 640, 350, 16, 2, 0xa000, FALSE },/* Mode 0x10 */
{ 0, 0, 640, 480, 2, 1, 0xa000, FALSE }, /* Mode 0x11 */
{ 0, 0, 640, 480, 16, 1, 0xa000, FALSE },/* Mode 0x12 */
{ 0, 0, 320, 200, 256, 1, 0xa000, FALSE },/* Mode 0x13 */
};
int mono; /* TRUE if on monochrome screen */
/* Remember: screen height is stored one less than actual!!! */
#define SetMode(m) PutMemB(data_segment, 0x49, m)
#define GetMode() GetMemB(data_segment, 0x49)
#define SetWidth(w) PutMemW(data_segment, 0x4a, w)
#define GetWidth() GetMemW(data_segment, 0x4a)
#define SetHeight(h) PutMemB(data_segment, 0x84, h)
#define GetHeight() GetMemB(data_segment, 0x84)
#define SetSize(s) PutMemW(data_segment, 0x4c, s)
#define GetSize() GetMemW(data_segment, 0x4c)
#define SetOffset(o) PutMemW(data_segment, 0x4e, o)
#define GetOffset() GetMemW(data_segment, 0x4e)
#define SetCx(page,cx) PutMemB(data_segment, 0x50+(page << 1), cx)
#define GetCx(page) GetMemB(data_segment, 0x50+(page << 1))
#define SetCy(page,cy) PutMemB(data_segment, 0x51+(page << 1), cy)
#define GetCy(page) GetMemB(data_segment, 0x51+(page << 1))
#define SetCs(s) PutMemB(data_segment, 0x61, s)
#define GetCs() GetMemB(data_segment, 0x61)
#define SetCe(s) PutMemB(data_segment, 0x60, s)
#define GetCe() GetMemB(data_segment, 0x60)
#define SetCp(cp) PutMemB(data_segment, 0x62, cp)
#define GetCp() GetMemB(data_segment, 0x62)
#define GetCRT() GetMemW(data_segment, 0x63)
#define SetCRT(c) PutMemW(data_segment, 0x63, c)
#define SetCharHeight(c) PutMemW(data_segment, 0x85, c)
#define GetCharHeight() GetMemW(data_segment, 0x85)
static int cur_emulate = TRUE;
static int pages; /* Maximum number of pages */
#define page_start(page) &screen_mem[GetSize()*(page)]
static BYTE functionality[] =
{
0xff, /* Modes 0->7 supported */
0x00, /* Modes 8->0x0f not supported yet */
0x00, /* Modes 0x10->0x13 not supported yet */
0,0,0,0, /* Reserved bytes */
0x04, /* Only 400 scan lines supported at the moment */
0x01, /* Character blocks */
0x01, /* Number of active character blocks */
0x04+0x08+0x16, /* Various functions */
0x04+0x08, /* ditto */
0,0, /* Reserved */
0x00, /* Various saved things */
0x00, /* Reserved */
};
static BYTE *get_offset(int page)
{
return &screen_mem[(GetSize() * page) + (2 * (GetCx(page) +
GetCy(page)*GetWidth()))];
}
static void clearscr(int x1,int y1,int x2,int y2,int attr)
{
BYTE *scr = &screen_mem[GetOffset()];
int x,y;
unsigned width = GetWidth();
for (y = y1; y <= y2; y++)
{
for (x = x1; x <= x2; x++)
{
scr[2*(x+y*width)] = ' ';
scr[2*(x+y*width)+1] = (BYTE)attr;
}
}
update_display();
}
static void scroll(int x1, int y1, int x2, int y2, int num, int attr)
{
int x,y;
unsigned width = GetWidth();
BYTE *scr;
if (x1 > x2 || y1 > y2)
return;
scr = &screen_mem[GetOffset()];
if (num == 0 || y2-y1 < abs(num))
{
clearscr(x1,y1,x2,y2, attr);
return;
}
if (num > 0)
{
disable(); /* To prevent occasional screen glitch */
for (y = y1; y <= y2-num; y++)
for (x = x1; x <= x2; x++)
{
scr[2*(x+y*width)] = scr[2*(x+(y+num)*width)];
scr[2*(x+y*width)+1] = scr[2*(x+(y+num)*width)+1];
}
y = y2-num+1;
copy_text(x1,y1+num,x2,y2,x1,y1);
enable();
}
else
{
num = -num;
disable(); /* To prevent occasional screen glitch */
for (y = y2-num; y >= y1; y--)
for (x = x1; x <= x2; x++)
{
scr[2*(x+(y+num)*width)] = scr[2*(x+y*width)];
scr[2*(x+(y+num)*width)+1] = scr[2*(x+y*width)+1];
}
y = y1;
copy_text(x1,y1,x2,y2-num,x1,y1+num);
enable();
}
clearscr(x1,y,x2,y+num-1,attr);
}
void set_cursor_type(unsigned start, unsigned end)
{
if (start == 0x20)
set_cursor_height(0, -1);
else
{
start &= 0x1f;
end &= 0x1f;
SetCs(start);
SetCe(end);
if (cur_emulate && GetMode() <= 3 && start <= 8 && end <= 8)
{
start = (GetCharHeight()*start)/8;
end = (GetCharHeight()*end)/8;
}
set_cursor_height(start, end);
}
}
static void set_mode(int mode)
{
if (mode < MAXMODE)
{
if (!mono || (defaults[mode].colours <= 2 && mono))
{
int i;
if (!defaults[mode].text)
return;
SetMode(mode);
SetWidth(defaults[mode].sx);
SetHeight(defaults[mode].sy-1);
SetSize(defaults[mode].sx * defaults[mode].sy * 2);
SetCp(0);
SetOffset(0);
if (mode == 0x7)
SetCRT(0x3b4);
else
SetCRT(0x3d4);
pages = defaults[mode].pages;
for (i = 0; i < pages; i++)
{
SetCx(i,0);
SetCy(i,0);
}
SetCharHeight(16);
set_cursor_type(defaults[mode].cs,defaults[mode].ce);
move_cursor(0, 0);
screen_mem = &memory[defaults[mode].base << 4];
new_screen(GetWidth(), GetHeight()+1, screen_mem);
}
}
}
static void display_message(void)
{
static char message1[] =
"PC Emulator v1.01alpha (C) 1994 University of Bristol";
static char message2[] =
"Please report comments, bugs etc to hedley@cs.bris.ac.uk";
BYTE *mem = get_offset(0);
int i;
disable();
for (i = 0; i < sizeof message1-1; i++)
mem[i<<1] = message1[i];
for (i = 0; i < sizeof message2-1; i++)
mem[(i+80)<<1] = message2[i];
SetCx(0, 0);
SetCy(0, 4);
move_cursor(GetCx(0),GetCy(0));
enable();
}
static void fill_in_functionality(void)
{
WORD tmp = ChangeE(wregs[DI]);
PutMemW(c_es, tmp, VIDEOFUNCTIONALITY);
tmp += 2;
PutMemW(c_es, tmp, 0xf000);
tmp += 2;
PutMemB(c_es, tmp, GetMode());
tmp++;
PutMemW(c_es, tmp, GetWidth());
tmp += 2;
PutMemW(c_es, tmp, GetSize());
tmp += 2;
PutMemW(c_es, tmp, GetSize() * GetCp());
tmp += 2;
PutMemB(c_es, tmp, GetCy(0));
tmp++;
PutMemB(c_es, tmp, GetCx(0));
tmp++;
PutMemB(c_es, tmp, GetCy(1));
tmp++;
PutMemB(c_es, tmp, GetCx(1));
tmp++;
PutMemB(c_es, tmp, GetCy(2));
tmp++;
PutMemB(c_es, tmp, GetCx(2));
tmp++;
PutMemB(c_es, tmp, GetCy(3));
tmp++;
PutMemB(c_es, tmp, GetCx(3));
tmp++;
PutMemB(c_es, tmp, GetCy(4));
tmp++;
PutMemB(c_es, tmp, GetCx(4));
tmp++;
PutMemB(c_es, tmp, GetCy(5));
tmp++;
PutMemB(c_es, tmp, GetCx(5));
tmp++;
PutMemB(c_es, tmp, GetCy(6));
tmp++;
PutMemB(c_es, tmp, GetCx(6));
tmp++;
PutMemB(c_es, tmp, GetCy(7));
tmp++;
PutMemB(c_es, tmp, GetCx(7));
tmp++;
PutMemB(c_es, tmp, GetCs());
tmp++;
PutMemB(c_es, tmp, GetCe());
tmp++;
PutMemB(c_es, tmp, GetCp());
tmp++;
PutMemW(c_es, tmp, GetCRT());
tmp += 2;
PutMemB(c_es, tmp, 0);
tmp++;
PutMemB(c_es, tmp, 0);
tmp++;
PutMemB(c_es, tmp, GetHeight()+1);
tmp++;
PutMemW(c_es, tmp, GetCharHeight());
tmp += 2;
PutMemB(c_es, tmp, mono ? 7 : 8);
tmp++;
PutMemB(c_es, tmp, 0);
tmp++;
PutMemW(c_es, tmp, mono ? 0 : 256);
tmp += 2;
PutMemB(c_es, tmp, defaults[GetMode()].pages);
tmp++;
PutMemB(c_es, tmp, 0x02);
tmp++;
PutMemB(c_es, tmp, 0);
tmp++;
PutMemB(c_es, tmp, 0);
tmp++;
PutMemB(c_es, tmp, mono ? 4 : 0);
tmp++;
PutMemW(c_es, tmp, 0);
tmp += 2;
PutMemB(c_es, tmp, 0);
tmp++;
PutMemB(c_es, tmp, 3);
tmp++;
PutMemB(c_es, tmp, 1);
}
void int_video(void)
{
unsigned page, al;
unsigned height, width;
D(printf("In Video. Function = %02X\n", *bregs[AH]););
CalcAll();
page = *bregs[BH];
al = *bregs[AL];
height = GetHeight();
width = GetWidth()-1;
switch(*bregs[AH])
{
case 0: /* Set mode */
set_mode(al & 0x7f);
if ((al & 0x80) == 0)
clearscr(0,0,width, height, 0x07);
break;
case 1: /* Set cursor type */
set_cursor_type(*bregs[CH], *bregs[CL]);
break;
case 2: /* Move cursor position */
if (page < pages)
{
SetCx(page, *bregs[DL]);
SetCy(page, *bregs[DH]);
move_cursor(GetCx(page),GetCy(page));
}
break;
case 3: /* Get cursor position */
if (page < pages)
{
*bregs[CH] = GetCs();
*bregs[CL] = GetCe();
*bregs[DL] = GetCx(page);
*bregs[DH] = GetCy(page);
}
break;
case 4: /* Light pen (!) */
*bregs[AH] = 0;
wregs[BX] = wregs[CX] = wregs[DX] = 0;
break;
case 5: /* Set display page */
if (al < pages)
{
SetCp(al);
SetOffset(al*GetSize());
new_screen(width+1, height+1, page_start(al));
update_display();
}
break;
case 6: /* Scroll down/clear window */
scroll(*bregs[CL], *bregs[CH], *bregs[DL], *bregs[DH], al, *bregs[BH]);
break;
case 7: /* Scroll up/clear window */
scroll(*bregs[CL], *bregs[CH], *bregs[DL], *bregs[DH], -al,*bregs[BH]);
break;
case 8: /* Read character and attribute at cursor */
if (page < pages)
{
BYTE *pos = get_offset(page);
*bregs[AL] = *pos++;
*bregs[AH] = *pos;
}
break;
case 9: /* Write character(s) and attribute(s) at cursor */
if (page < pages)
{
BYTE *pos = get_offset(page);
unsigned i, count;
count = ChangeE(wregs[CX]);
for (i = count; i > 0; i--)
{
*pos++ = al;
*pos++ = *bregs[BL];
}
if (count > 1)
update_display();
else
if (count == 1)
displaychar();
}
break;
case 0x0a: /* Write character at cursor */
if (page < pages)
{
BYTE *pos = get_offset(page);
unsigned i, count;
count = ChangeE(wregs[CX]);
for (i = count; i > 0; i--)
*pos++ = al;
if (count > 1)
update_display();
else
if (count == 1)
displaychar();
}
break;
case 0x0b: /* Set palette/background/border */
break;
case 0x0e: /* Write character in teletype mode */
if (page < pages)
{
BYTE *pos = get_offset(page);
int x,y;
x = GetCx(page);
y = GetCy(page);
switch(al)
{
case 0x0a: /* Line feed */
y++;
break;
case 0x0d: /* Return */
x = 0;
break;
case 0x8: /* Backspace */
x--;
break;
case 0x7: /* Bell */
fprintf(stderr,"\a");
fflush(stderr);
break;
default:
*pos = al;
x++;
displaychar();
}
if (x > width)
{
x = 0;
y++;
}
if (x < 0)
{
x = width;
y--;
}
if (y > height)
{
BYTE attr;
y = height;
attr = screen_mem[GetSize()*(page+1) -1];
scroll(0,0,width,y,1,attr);
}
if (y < 0)
{
y = 0;
scroll(0,0,width,height,-1,7);
}
SetCx(page,x);
SetCy(page,y);
move_cursor(x,y);
}
break;
case 0x0f: /* Return information */
*bregs[AL] = GetMode();
*bregs[AH] = width+1;
*bregs[BH] = GetCp();
break;
case 0x10: /* Colour/palette stuff... */
break;
case 0x11: /* Font stuff... */
switch(*bregs[AL])
{
case 0x02: /* Load rom 8x8 font (set 50/42 lines) */
case 0x12:
height = 49;
SetHeight(height);
SetSize((width+1) * (height+1) * 2);
new_screen(width+1, height+1, screen_mem);
clearscr(0,0,width, height, 0x07);
break;
case 0x30: /* Get font information */
switch(*bregs[BH])
{
default:
wregs[CX] = ChangeE(16);
*bregs[DL] = height;
sregs[ES] = 0xf000;
c_es = SegToMemPtr(ES);
wregs[BP] = ChangeE(0);
}
break;
default:
printf("Unimplemented int 0x10 function 0x11 sub-function %02X\n",*bregs[AL]);
#ifdef DEBUG
loc();
exit_emu();
#endif
break;
}
break;
case 0x12: /* Display information */
switch(*bregs[BL])
{
case 0x10: /* Get config info */
*bregs[BH] = mono;
*bregs[BL] = 3;
wregs[CX] = ChangeE(0);
break;
case 0x30: /* Set scan lines */
*bregs[AL] = 0x12;
break;
case 0x34: /* Enable/disable cursor emulation */
cur_emulate = *bregs[AL] == 0;
*bregs[AL] = 0x12;
break;
default:
printf("Unimplemented int 10 function 0x12 sub-function 0x%02X\n",*bregs[BL]);
#ifdef DEBUG
loc();
exit_emu();
#endif
break;
}
break;
case 0x1a: /* Get/Set display combination */
if (*bregs[AL] == 0)
{
*bregs[BL] = mono ? 7 : 8;
*bregs[BH] = 0;
*bregs[AL] = 0x1a;
}
break;
case 0x1b: /* Get functionality/state information etc */
fill_in_functionality();
*bregs[AL] = 0x1b;
break;
case 0x30: /* ??? Called by MSD.EXE */
case 0x4f: /* VESA functions... */
case 0x6f: /* ??? Called by borland C */
case 0xcc: /* ??? Called by Norton's disk edit */
case 0xef: /* ??? Called by QBASIC.EXE */
case 0xfa: /* ??? Called by MSD.EXE (Microsoft Diagonstics) */
case 0xfe: /* ??? - but several programs call it. Appears to do nothing */
case 0xff: /* ??? Called by WordPerfect 5.1 */
break;
default:
printf("Unimplemented int 10 function: %02X. AL = %02X BL = %02X\n",
*bregs[AH], *bregs[AL], *bregs[BL]);
#ifdef DEBUG
loc();
exit_emu();
#endif
break;
}
}
void init_vga(void)
{
int mode = mono ? 7 : 3;
static BYTE afterint[] =
{
0xfb, 0xca, 0x02, 0x00
};
init_hardware();
screen_mem = &memory[defaults[mode].base << 4];
data_segment = &memory[0x00400];
memcpy(&memory[0xf0000+VIDEOFUNCTIONALITY], &functionality, sizeof functionality);
set_mode(mode);
clearscr(0,0,GetWidth()-1, GetHeight(), 0x07);
set_int(0x10, NULL, 0, int_video, afterint, sizeof afterint);
display_message();
}
void vga_off(void)
{
finish_hardware();
}