#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <dos.h>
/*
* MSCDEX Substitute
*
* Operation:
* This is a TSR that inserts itself before the real MSCDEX interrupt
* service routines. It is a dummy version of MSCDEX for NFS use, and
* emulates the following services:
*
* 00h Get Number of CD ROM Drives
* 01h Get CD-ROM Drive Device List
* 02h Get Copyright File Name
* 03h Get Abstract File Name
* 04h Get Bibliographic Doc File Name
* 05h Get VTOC (partially emulated - not sure if okay)
* 06h Turn Debugging on
* 07h Turn Debugging off
* 08h Absolute Disk Read - Emulated to return error 21
* 09h Absolute Disk Write - NOT SUPPORTED
* 0ah (Reserved)
* 0bh CD ROM Drive check
* 0ch MSCDEX Version
* 0dh Get CD Drive Letters
* 0eh Get/Set Volume Descriptor Preference
* 0fh Get Directory Entry - NOT SUPPORTED
* 10h Send Device Driver Request - NOT SUPPORTED
*
* Also, it uses a reserved service ff, so that the parameters to the
* TSR are able to be altered after it is set running. The services
* are passed through register BX, eg:
*
* AX = ffh, Bx =
* 00, Install drive in cx, eg cx=0, Drive A,
* cx=1, Drive B, etc..
* 01, Remove drive in cx, eg cx=0, Drive A, etc
* 02, Set mscdex version number, eg cx = 0x020a => 2.10
* 03, Turn off this mscsub, pass over to normal handler
* 04, Turn on mscsub.
* 05, Change name of device driver (eg MSCD000)
* 06, Change name of file that contains data for
* sub-functions 02h, 03h, 04h for each drive.
*
*
* How to load:
* After MSCDEX is loaded, you can load this either by running it, or
* load it into high memory using loadhigh. Eg: loadhigh mscsub ...
*
* Syntax:
* MSCMON drive ...
*
* drive ... Letters of the CD ROM drives for MSCMON to emulate.
*
* Example:
* MSCMON D E F Load for CD Drives D: E: and F:
*
* Compiler Used:
* Borland C++, 3.1
*
* Compile: bcc -1 -ml mscmon.c
*
* Test History:
* Works okay on 486's and 386's. I haven't tried it out on any 286's yet.
*
* Author: Colin Ian King, Templeman Library, University of Kent.
*
* Modification Record:
* 01/03/93 Creation Date.
* 15/03/93 Add full set of MSCDEX functions.
*/
#define MAX_DRIVES 10
#define TRUE 1
#define FALSE 0
#define INT2F 0x2f
extern unsigned _heaplen = 1024;
extern unsigned _stklen = 512;
void exit(int);
static long unsigned int drive_map = 0L;
static unsigned int mscdex_version = 0x020a; /* 2.10 */
static int quite_mode = 0;
static char mscdex[] = "MSCD000";
static char mscdat[64] = "MSCSUB.DAT";
static char buffer[40];
static struct DHD {
char far *next;
int devattr;
void (near *devep1)();
void (near *devep2)();
char devname[8];
int reserved;
char driveletter;
char numofunits;
} devhead;
void near
nothing()
{
}
void
getinfo(char drive, char* axr, char* filename, char*ptr)
{
FILE *fp;
char buffer[42];
strcpy(ptr,"");
if ((fp = fopen(filename,"r")) == NULL) {
return;
}
for (;;) {
if (fgets(buffer,41,fp)==NULL)
goto done;
if (strncmp(axr,buffer,4)==0)
break;
}
for (;;) {
if (fgets(buffer,41,fp)==NULL)
goto done;
if (*buffer == drive)
break;
}
buffer[40] = '\0';
buffer[strlen(buffer)-1] = '\0';
strcpy(ptr,buffer+2);
done:
fclose(fp);
}
static void interrupt (*oldfunc)(unsigned bp, unsigned di, unsigned si,
unsigned ds, unsigned es, unsigned dx,
unsigned cx, unsigned bx, unsigned ax);
void interrupt show_regs(unsigned bp, unsigned di, unsigned si,
unsigned ds, unsigned es, unsigned dx,
unsigned cx, unsigned bx, unsigned ax)
{
char *p;
int i, j;
unsigned long sh;
struct DLL {
char subunit;
struct DHD far *devhead;
} *dll;
if ((ax & 0xff00) == 0x1500) {
/*
* If turned off, do the normal handling and forget this
* handler altogether, UNLESS it is one my mscsub
* own command codes when al = 0xff. Sneaky.
*/
if (quite_mode) {
if ((ax & 0xff) != 0xff) {
_chain_intr(oldfunc);
}
}
switch(ax & 0xff) {
/*
* MSCSUB sub command switches for altering the context.
*
* bx sub-command:
* 00, Install drive in cx, eg cx=0, Drive A,
* cx=1, Drive B, etc
* 01, Remove drive in cx, eg cx=0, Drive A, etc
* 02, Set mscdex version number, eg cx = 0x020a => 2.10
* 03, Turn off this mscsub, pass over to normal handler
* 04, Turn on mscsub.
* 05, Change name of device driver (eg MSCD000)
* name in ES:BX, name is 8 chars (including '\0')
* 06, Change name of file that contains data for
* sub-functions 02h, 03h, 04h for each drive.
* name in ES:BX, name is 64 chars (including '\0')
*/
case 0xff:
switch (bx & 0xff) {
case 0x00:
drive_map |= 1L << (cx & 0x1f);
break;
case 0x01:
drive_map &= (0x1f ^ (1L << (cx & 0x1f)));
break;
case 0x02:
mscdex_version = cx;
break;
case 0x03:
quite_mode = 1;
break;
case 0x04:
quite_mode = 0;
break;
case 0x05:
p = (char *)((((long) es) << 16) + cx);
strncpy(mscdex,p,8);
break;
case 0x06:
p = (char *)((((long) es) << 16) + cx);
strncpy(mscdat,p,64);
break;
default:
break;
}
break;
case 0x00:
cx = 0xffff;
for (i=0,bx = 0, sh=drive_map; sh; sh >>= 1,i++) {
if (sh & 0x01) {
bx++;
if (cx == 0xffff) {
cx = i;
}
}
}
break;
case 0x01:
dll = (struct DLL *)((((long) es) << 16) + bx);
for (i=0,j = 0, sh=drive_map; sh; sh >>= 1,i++) {
if (sh & 0x01) {
dll[j].subunit = j;
dll[j].devhead = (struct DHD *)&devhead;
j++;
devhead.driveletter = i + 1; // magic
}
}
devhead.next = (char far*)-1; /* List End */
devhead.devattr = 32768+16384+2048; /* Magic */
devhead.devep1 = nothing; /* Do nothing */
devhead.devep2 = nothing;
strncpy(devhead.devname,mscdex,8);
devhead.reserved= 0;
devhead.numofunits=j;
break;
/*
* Copyright File Name
*/
case 0x02:
p = (char *)((((long) es) << 16) + bx);
getinfo(cx+'A',"1502",mscdat,p);
break;
/*
* Abstract File Name
*/
case 0x03:
p = (char *)((((long) es) << 16) + bx);
getinfo(cx+'A',"1503",mscdat,p);
break;
/*
* Bibliographic Documentation File Name
*/
case 0x04:
p = (char *)((((long) es) << 16) + bx);
getinfo(cx+'A',"1504",mscdat,p);
break;
/*
* Read VTOC - Set AX to FFh for Volume Descriptor
* Terminator record found.
*/
case 0x05:
ax = 0x00ff;
break;
/*
* 0x06: Debugging turned on
* 0x07: Debugging turned off
*/
case 0x06:
case 0x07:
break;
/*
* Bodge Absolute Disk Read, Force DOS error 21.
*/
case 0x08:
ax = 0x0021; /* Error_Not_Ready */
asm {
stc
}
break;
/*
* 0x09: Forget about Absolute Disk Write
* 0x0a: Reserved, so ingnore..
*/
case 0x09:
case 0x0a:
break;
/*
* CD-ROM Drive Check, drive = cx
*/
case 0x0b:
if (drive_map & (1L << (cx & 0x1f))) {
bx = 0xadad; /* Magic */
ax = 0xffff; /* Any Non Zero will do? */
}
else {
ax = 0x0000; /* MSCDEX non supported for
* drive in cx */
}
break;
/*
* MSCDEX Version Number
*/
case 0x0c:
bx = mscdex_version;
break;
/*
* Get CD ROM Drive Letters, ES:BX = buffer
*/
case 0x0d:
p = (char *)((((long) es) << 16) + bx); // o/p buffer ptr
for (i = 0, sh=drive_map; sh; sh >>= 1,i++) {
if (sh & 0x01) {
*p++ = (char)i;
}
}
break;
/*
* Get/Set Volume Descriptor Preferences
*/
case 0x0e:
if (drive_map & (1L << (cx & 0x1f))) {
switch (bx & 0xff) {
/*
* Get...
*/
case 0x00:
dx = 0; /* This version of MSCDEX does not
support SVD's */
break;
/*
* Set...
*/
case 0x01:
dx = 0; /* No preference!?? */
break;
default:
ax = 1; /* Error Invalid Function */
break;
}
}
else {
ax = 15; /* Error Invalid Drive */
}
break;
default:
break;
}
}
else {
_chain_intr(oldfunc);
}
}
/*
* Append to vector and TSR
*/
int
main(int argc, char** argv)
{
char *ptr;
char ch;
int sh,
i;
/*
* Scan & parse drive list
*/
fprintf(stdout,"MSCDEX Substitute, by cik@ukc.ac.uk, V0.1, ");
if (argc < 2) {
fprintf(stdout,"\nUsage: MSCSUB drive ...\n");
exit(1);
}
if (argc > 26) {
fprintf(stdout,"\nMaximum of 26 drives allowed\n");
exit(1);
}
for (i = 1; i<argc; i++) {
ch = argv[i][0];
if (!isalpha(ch)) {
fprintf(stdout,"\n%c is not a drive\n",argv[i][0]);
exit(1);
}
drive_map |= 1L << ((ch-'A') & 0x1f);
}
for (i = 0, sh=drive_map; sh; sh >>= 1,i++) {
if (sh & 0x01) {
fprintf(stdout,"%c: ",(char)(i+'A'));
}
}
oldfunc = _dos_getvect(INT2F);
_dos_setvect(INT2F,show_regs);
_dos_keep(0, (_SS + 20 + (_SP/16) - _psp));
return 0;
}
