$compact
$title ('SDIR 8086 - Get Disk Parameters')
dpb86:
do;
       /* the purpose of this module is to allow independence */
       /* of processor, i.e., 8080 or 8086                    */

$include (comlit.lit)

/* function call 32 in 2.0 or later BDOS, returns the address of the disk
parameter block for the currently selected disk, which consists of:
        spt                   (2 bytes) number of sectors per track
        blkshf                (1 byte)  block size = shl(double(128),blkshf)
        blkmsk                (1 byte)  sector# and blkmsk = block number
        extmsk                (1 byte)  logical/physical extents
        blkmax                (2 bytes) max alloc number
        dirmax                (2 bytes) size of directory-1
        dirblk                (2 bytes) reservation bits for directory
        chksiz                (2 bytes) size of checksum vector
        offset                (2 bytes) offset for operating system
*/

$include(dpb.lit)

declare k$per$block byte public;
declare dpb$base pointer;
declare dpb$array based dpb$base (15) byte;

mon4: procedure (f,a) pointer external;
    dcl f byte, a address;
end mon4;

dcl get$dpb lit '31';

dpb$byte: procedure(param) byte public;
    dcl param byte;
    return(dpb$array(param));
end dpb$byte;

dpb$word: procedure(param) address public;
    dcl param byte;
    return(dpb$array(param) + shl(double(dpb$array(param+1)),8));
end dpb$word;

base$dpb: procedure public;
    dpb$base = mon4(get$dpb,0);
    k$per$block = shr(dpb$byte(blkmsk$b)+1 ,3);
end base$dpb;

end dpb86;