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/*
** DRIVSRCH.C - public domain by Marty Connelly, Victoria, BC 1992
**
** Modified by Bob Stout
**
** Routine checks how many valid disk drives are available on machine,
** both physical and logical drives
*/
/*
** Includes drive letters assigned with DOS SUBST command
**
** Networked drives are left as an exercise as I don't have access
** to them to check.
**
** The routine uses undocumented DOS interrupt 32H.
**
** Compatible with MSC 5 and 6, ZTC++, BC++, other DOS compilers
**
** DS:BX contains the address of the Disk Parameter Block (DPB) for a
** requested drive. If the drive letter at offset 0 of the DPB doesn't
** match the requested drive, then the drive has been SUBST'ed.
*/
#include <stdio.h>
#include <dos.h>
#if !defined(MK_FP)
#define MK_FP(seg,off) ((void far *)(((long)(seg) << 16)|(unsigned)(off)))
#endif
#ifdef __TURBOC__
#define _far far
#endif
void main(void)
{
int i;
int unsigned result;
int drivestatus[26];
unsigned char _far *DPB;
union REGS regs;
struct SREGS sregs;
/* routine checks for all valid drive possibilities from A to Z */
/*
** if removeable media drive ie. floppy drive A: has a latch door
** open you will get "Abort Retry" panic message
*/
for (i = 0; i < 26; i++)
{
/* drive number (0=default, 1=A, 2=B,etc.)*/
regs.h.dl = (unsigned char)(i + 1);
segread(&sregs);
regs.h.ah=0x32; /* DOS interrupt 32H */
/* was undocumented for DOS release 3.2 */
intdosx(®s,®s, &sregs);
result=regs.h.al;
DPB = MK_FP(sregs.ds, regs.x.bx);
/*
** result =0 then valid drive
** =255 or ff hex then invalid or non-existent drive
*/
if (0 == result && *DPB != (unsigned char)i)
drivestatus[i] = 1;
else drivestatus[i]=result;
}
for (i = 0; i < 26; i = i + 2)
{
printf("drive %c: status code =%3d drive %c: status code =%3d\n",
'A' + i,drivestatus[i],'B' + i,drivestatus[i+1]);
}
return;
}
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