Write a c program to display mouse pointer



Write a c program to display mouse pointer

#include <dos.h>
#include <stdio.h>
void main()
{
union REGS i,o;
i.x.ax=1;
int86(0x33,&i,&o);
getch();
}

Explanation: To write such program you must have one interrupt table. Following table is only small part of interrupt table.
This table consists for column. They are:
(1)   Input
(2)   Output
(3)   Service number
(4)   Purpose

Now look at the first row of interrupt table. To show the mouse pointer assign ax equal to 1 i.e. service number while ax is define in the WORDREGS

struct WORDREGS {
unsigned int ax, bx, cx, dx;
unsigned int si, di, cflag, flags;
};

And WORDRGS is define in the union REGS

union REGS {
struct WORDREGS x;
struct BYTEREGS h;
};

So to access the structure member ax first declare a variable of REGS i.e.

REGS i, o;
Note: We generally use i for input and o for output

To access the ax write i.x.ax (We are using structure variable i because ax is input
(See in the interrupt table)

So to show mouse pointer assign the value of service number to it:

i.x.ax=1;

To provide this information to microprocessor
we use int86 function. It has three parameters

1. Interrupt number i.e.
0x33
2. union REGS *inputregiste i.e. &i
3. union REGS *outputregiste i.e. &o;
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