Category : C Source Code
Archive : ASMPROCS.ZIP
Filename : IBMPC.CPP
Output of file : IBMPC.CPP contained in archive : ASMPROCS.ZIP
//
// Low-level functions addressing BIOS & PC Hardware
//
// Original code written by: Al Stevens for the Aztec C compiler
// Modified for Turbo C++ 2.0
//
// Compile to object using BCC or BCCX:
// bccx -c ibmpc
//
// To use TASM remove the comment prior to the #pragma inline and compile.
// This provides a good example where inline statements should be used. The
// best example is Al Steven's use of inline statements to quickly retrieve
// system information on video retrace.
//
// #pragma inline
#include
static union REGS rg;
// position the cursor
void pascal cursor(int x, int y)
{
rg.x.ax = 0x0200;
rg.x.bx = 0;
rg.x.dx = ((y << 8) & 0xff00) + x;
int86(16, &rg, &rg);
}
// return the cursor position
void pascal curr_cursor(int *x, int *y)
{
rg.x.ax = 0x0300;
rg.x.bx = 0;
int86(16, &rg, &rg);
*x = rg.h.dl;
*y = rg.h.dh;
}
// set cursor type
void pascal set_cursor_type(int t)
{
rg.x.ax = 0x0100;
rg.x.bx = 0;
rg.x.cx = t;
int86(16, &rg, &rg);
}
char attrib = 7;
// clear the screen
void pascal clear_screen()
{
cursor(0, 0);
rg.h.al = ' ';
rg.h.ah = 9;
rg.x.bx = attrib;
rg.x.cx = 2000;
int86(16, &rg, &rg);
}
// return the video mode
int pascal vmode()
{
rg.h.ah = 15;
int86(16, &rg, &rg);
return rg.h.al;
}
// test for scroll lock
int pascal scroll_lock()
{
rg.x.ax = 0x0200;
int86(0x16, &rg, &rg);
return rg.h.al & 0x10;
}
void (*helpfunc)();
int helpkey = 0;
int helping = 0;
// insert a character and attribute into video RAM
void pascal vpoke(unsigned vseg, unsigned adr, unsigned chr)
{
if (vseg == 45056) /* monochrome mode */
poke(vseg, adr, chr);
else {
_DI = adr; /* offset of video character */
_ES = vseg; /* video segment */
asm cld;
_BX = chr; /* the attribute and character */
_DX = 986; /* video status port */
// wait for video retrace to start
do
asm in al,dx;
while (_AL & 1);
// wait for video retrace to stop
do
asm in al,dx;
while (!(_AL & 1));
_AL = _BL;
asm stosb; /* store character */
// wait for video retrace to start
do
asm in al,dx;
while (_AL & 1);
// wait for video retrace to stop
do
asm in al,dx;
while (!(_AL & 1));
_AL = _BH;
asm stosb; // store attribute
}
}
// read a character and attribute from video RAM
int pascal vpeek(unsigned vseg, unsigned adr)
{
int ch, at;
if (vseg == 45056) // monochrome mode
return peek(vseg, adr);
asm push ds;
_DX = 986; // video status port
_DS = vseg; // video segment address
_SI = adr; // video character offset
asm cld;
// wait for video retrace to start
do
asm in al,dx;
while (_AL & 1);
// wait for video retrace to stop
do
asm in al,dx;
while (!(_AL & 1));
asm lodsb; /* get the character */
_BL = _AL;
// wait for video retrace to start
do
asm in al,dx;
while (_AL & 1);
// wait for video retrace to stop
do
asm in al,dx;
while (!(_AL & 1));
asm lodsb; // get the attribute
_BH = _AL;
_AX = _BX;
asm pop ds;
return _AX;
}
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