/* ----------------------------------------------------
* Author: T.W. Nelson
* Compile options:
* Version: 1.00
* Date: 05-0ct-1991
* Notes:
*
* Source code Copyright (c) 1991 T.W. Nelson.
* May be used only with appropriate
* acknowledgement of copyright.
* -------------------------------------------------- */
#include <dos.h>
#include "driver.h"
extern unsigned init(void), media_check(void),
build_bpb(void), ioctl_read(void),
device_read(void), nd_read(void),
input_status(void), input_flush(void),
device_write(void), verify_write(void),
output_status(void), output_flush(void),
ioctl_write(void), device_open(void),
device_close(void), rem_media(void),
output_busy(void), generic_ioctl(void),
get_logdev(void), set_logdev(void),
bad_command(void);
static unsigned (*Dispatch[])(void) = {
init, //0 = initialize driver
media_check, //1
build_bpb, //2 = build BIOS param block
ioctl_read, //3 = read io control data
device_read, //4
nd_read, //5 = non-destructive read
input_status, //6
input_flush, //7 = flush input buffers
device_write, //8
verify_write, //9 = write with verify
output_status, //10
output_flush, //11 = flush output buffers
ioctl_write, //12 = write io control data
device_open, //13 (DOS 3+)
device_close, //14 (DOS 3+)
rem_media, //15 = removable media (3+)
output_busy, //16 = output until busy (3+)
bad_command, //17 = not used
bad_command, //18 = not used
generic_ioctl, //19 = generic io control (3.2+)
bad_command, //20 = not used
bad_command, //21 = not used
bad_command, //22 = not used
get_logdev, //23 = get logical device (3.2+)
set_logdev, //24 = set logical device (3.2+)
};
#define NUM_CMDS (sizeof(Dispatch)/sizeof(void *))
REQHDR far *Rh = (REQHDR far *) 0;
unsigned int errno = 0; //for std library code
extern unsigned tape_io(unsigned ofs, unsigned seg);
static char signon[] =
"Demo TAPE device driver, V1.00\r\n\n";
void exec_command( REQHDR far *rhdr )
{
/* Call the command-code routine from the dispatch
* table indexed by the command code. Access to
* caller's request header is made available thru
* global pointer 'Rh'. 'DONE' bit is always set
* on exit.
*/
Rh = rhdr; //assign to global copy
Rh->status = 0; //clear status word
Rh->status = ( (Rh->cmd >= NUM_CMDS) ?
bad_command() :
(*Dispatch[ Rh->cmd ])() );
Rh->status |= IM_DONE; //set 'done' bit
}
/*----------------------------------------------------
* Command-code routines. Called indirectly by the
* interrupt routine thru the dispatch table. All
* routines should return the appropriate status code
* to be assigned to the request header on return to
* exec_command(). Return will be 0 if no error,
* or (IS_ERROR + error_code) (see driver.h) if an
* error was detected.
*----------------------------------------------------*/
unsigned init( void ) /* 0 */
{
/* Driver initialization function. Called once
* by DOS on boot up when CONFIG.SYS is read.
* Only DOS functions 01h-OCh and 30h can be called
* here.
*/
extern char _TheEnd; //marks end of driver
void putstr( const char *str ); //below
putstr( signon);
/* Other initialization code goes here ......
* If needed, a pointer to the command line after
* 'DEVICE=' in CONFIG.SYS is available starting
* at Rh->xfer_cnt (or, Rh + 18).
*/
// Return break address to DOS .......
Rh->xfer_seg = FP_SEG( (void far *) &_TheEnd );
Rh->xfer_ofs = FP_OFF( (void far *) &_TheEnd );
return 0;
}
unsigned media_check( void ) /* 1 */
{
/* Block devices only. Function determines
* whether or not a floppy disk was changed,
* allowing DOS to bypass re-reading the FAT.
*/
return 0; }
unsigned build_bpb(void) /* 2 */
{
/* Block devices only. Builds a table of disk
* parameters when media_check() returns the
* disk-change code.
*/
return 0; }
unsigned ioctl_read(void) /* 3 */
{
/* Character and block devices. Allows device
* driver to pass data directly to application.
* Called by DOS int21h/44h subfunction 2. The
* IOCTL_RW bit (14) must be set in device block's
* attribute word.
*/
return tape_io(Rh->xfer_ofs, Rh->xfer_seg);
}
unsigned device_read(void) /* 4 */
{
/* Character and block devices. Read data from
* the device into a specified buffer. Returns
* #bytes or sectors transfered.
*/
return 0; }
unsigned nd_read(void) /* 5 */
{
/* Character devices only. Lets caller peek at
* next byte in device's buffer w/o removing it.
*/
return 0; }
unsigned input_status(void) /* 6 */
{
/* Character devices only. Returns current input
* status for device. Sets IM_BUSY bit if input
* request cannot proceed immediately (characters
* are waiting to be read from the input buffers).
*/
return 0; }
unsigned input_flush(void) /* 7 */
{
/* Character devices only. Function discards any
* data pending in device's input buffers.
*/
return 0; }
unsigned device_write(void) /* 8 */
{
/* Character and block devices. Writes data from
* the specified buffer to a device. Returns #
* bytes or sectors written.
*/
return 0; }
unsigned verify_write(void) /* 9 */
{
/* Character and block devices. Same as
* device_write(), but performs a read-after-
* write verification.
*/
return 0; }
unsigned output_status(void) /* 10 */
{
/* Character devices only. Returns the current
* output status for the device. Sets IM_BUSY bit
* if write request cannot proceed immediately.
*/
return 0; }
unsigned output_flush(void) /* 11 */
{
/* Character devices only. Function discards any
* data in output buffers and any pending output
* requests.
*/
return 0; }
unsigned ioctl_write(void) /* 12 */
{
/* Character and block devices. Allows application
* to pass control info directly to driver. Called
* by DOS int21h/44h subfunction 3. The IOCTL_RW
* bit (14) must be set in device block's attribute
* word.
*/
return tape_io(Rh->xfer_ofs, Rh->xfer_seg);
}
unsigned device_open(void) /* 13 */
{
/* Character and block devices, DOS 3+. Manages
* reference count of #open files for block devices,
* or device initialization for character devices.
* Called only if bit 11 (OCR_MEDIA) is set in
* attribute word in header block.
*/
return 0; }
unsigned device_close(void) /* 14 */
{
/* Character and block devices, DOS 3+. The
* opposite of command-code 13, device_open().
*/
return 0; }
unsigned rem_media(void) /* 15 */
{ /* Block devices only. Sets IM_BUSY if media is
* non-removable. Called only if bit 11
* (OCR_MEDIA) is set in attribute word in header
* block.
*/
return 0; }
unsigned output_busy(void) /* 16 */
{
/* Character devices only, DOS 3+. Transfers data
* to a device from specified buffer until device
* signals busy. Called only if attribute bit 13
* (OUTPUT_BUSY) is set.
*/
return 0; }
unsigned generic_ioctl(void) /* 19 */
{
/* Character and block devices, DOS 3.2+. This
* function is generally the same as command-codes
* 3 and 12, with a different calling protocol. Bit
* 6 (GEN_IOCTL) must be set in attribute word.
*/
return 0; }
unsigned get_logdev(void) /* 23 */
{
/* Block devices only, DOS 3.2+. Function returns
* number of logical devices (drive letters)
* assigned to a physical device. Bit 6
* (GEN_IOCTL) must be set in attribute word.
*/
return 0; }
unsigned set_logdev(void) /* 24 */
{
/* Block devices only, DOS 3.2+. Function sets
* number of logical devices assigned to a
* physical device. Bit 6 (GEN_IOCTL) must be set
* in attribute word.
*/
return 0; }
unsigned bad_command( void )
{
return IS_ERROR + INV_COMMAND;
}
void putstr( const char *str )
{
/* Utility function to output an asciiz-format
* string to monitor using BIOS-level output....
* Doesn't add an auto-CR; use '\r' in your
* string. Coding putstr() in C adds 200-300 more
* bytes (from int86()) to the TAPE.SYS image in
* memory, relative to an asm version.
*/
union REGS regs;
while( *str) {
regs.h.al = (char) *str++;
regs.h.ah = 0x0e; //BIOS write TTY
regs.x.bx = 0; //page 0
int86( 0x10, ®s, ®s );
}
}
/* ------ End of File --------------------*/