/* SCREENSZ.C */
 /* Queery system for screen size */

    /* Coding for TC 2.0 */

 /* After fruitlessly trying to find out how to find a modified screen's 
    row and column, I finally found the memory location needed in
    COMPUTE!'s Mapping the IBM PC and PCjr. (1985, Page 182)
    I looked at the TC reference guide and The MSDOS Encyclopedia to no
    avail.  (It might be in the Encyclopedia, but I couldn't find it!)
    This code fragment is very useful when a screen is changed
    to 40/43/50 lines (using Norton's NCC for example).

    Coding by Albert Stein, Chemical Bank, 212-310-3927
              Software Ideology
              PO Box 305, Brooklyn, NY  11204

    Any comments are welcome.  Enjoy!
 */

#include <stdio.h>
#include <mem.h>
#include <conio.h>
#include <dos.h>

#define STATE       15

void read_screensize (int *rows, int *cols,int type);

int rows,cols;

void main()
{
    read_screensize (&rows,&cols,1);
    printf ("reported by bios:  rows=%d  cols=%d\n",rows,cols);
    read_screensize (&rows,&cols,0);
    printf ("reported by location:  rows=%d  cols=%d\n",rows,cols);
}

void read_screensize (int *rows, int *cols,int type)
{
    union REGS regs;
    unsigned int value;
    unsigned int far *pvalue = &value;

    if (type == 1)
    {   regs.h.ah = 0x0F;
        int86(0x10,&regs,&regs);
        *cols = regs.h.ah;
        switch (regs.h.al)
        {   case 0x00:
            case 0x01:
            case 0x02:
            case 0x03:
            case 0x07:
                *rows = 25;
                break;
            default:
                printf ("Unexpected mode=0x%02x\n",regs.h.al);
                getch();
        }
    }
    else
    {   movedata (0x000,0x044A,FP_SEG(pvalue),FP_OFF(pvalue),2);
        *cols = *pvalue;
            /* this will return the total memory space in use */
        movedata (0x000,0x044C,FP_SEG(pvalue),FP_OFF(pvalue),2);
        *rows = *pvalue / (*cols * 2);
    }
}