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Shareware Grab Bag
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Shareware Grab Bag.iso
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007
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vdisk.aqm
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vdisk.asm
Wrap
Assembly Source File
|
1983-03-19
|
9KB
|
373 lines
; This is the DOS 2.0 ELECTRONIC DISK from the example in the DOS 2.0
; manual. It is now set for 180K of space. Look for the ======> 2 locations
; to change the size.
;
; To include the drive into your system, edit a file called CONFIG.SYS. It
; does not exist on the system supplied by IBM. Create a new file, and type
; in DEVICE=VDISK.COM
; and save the file (must be standard ASCII fornat!).
; make sure you copy VDISK.COM to your boot disk.
; When you boot, the number of disk drives will be determined from the
; switch setting and the ELECTRONIC DIDK will be made the next drive letter.
;
; For example, if you have two floppies, the RAM DISK will be Drive C.
;
;
; Assemble this will MASM and link with LINK pgm.
; You must then use the EXE2BIN command, type EXE2BIN VDISK VDIDK
; after that, you must rename the new file RENAME VDIDK.BIN VDISK.COM
;
cseg segment para public 'code'
status macro state,err,rc
ifidn <state>,<done>
or es:word ptr srh_sta_fld[bx],0100h
endif
ifidn <state>,<busy>
or es:word ptr srh_sta_fld[bx],0200h
endif
ifidn <err>,<error>
or es:word ptr srh_sta_fld[bx],1000h
endif
ifnb <rc>
or es:word ptr srh_sta_fld[bx],rc
endif
endm
;
;
;
srh equ 0
srh_len equ 13
srh_len_fld equ srh
srh_ucd_fld equ srh+1
srh_ccd_fld equ srh+2
srh_sta_fld equ srh+3
srh_res_fld equ srh+5
;
md equ srh+srh_len
md_len equ 1
dta equ md+md_len
dta_len equ 4
count equ dta+dta_len
count_len equ 2
ssn equ count+count_len
ssn_len equ 2
;
ret_byte equ md+md_len
;
bpba_ptr equ dta+dta_len
bpda_ptr_len equ 4
;
units equ srh+srh_len
units_len equ 1
br_addr_0 equ units+units_len
br_addr_1 equ br_addr_0+2
br_addr_len equ 4
bpb_ptr_off equ br_addr_0+br_addr_len
bpb_ptr_seg equ bpb_ptr_off+2
;
vdsk proc far
assume cs:cseg,es:cseg,ds:cseg
begin:
start equ $
;
next_dev dd -1
attribute dw 2000h
strategy dw dev_strategy
interrupt dw dev_int
dev_name db 1
db 7 dup(?)
;
rh_off dw ?rh_seg dw ?;
bpb equ $
dw 512
db 1
dw 1
db 2
dw 64
dw 360
db 0fch
dw 2
;
bpb_ptr dw bpb
;
; current virtual disk information
;
total dw ?verify db 0
start_sec dw 0
vdisk_ptr dw 0
user_dta dd ?boot_rec equ $
db 3 dup(0)
db 'IBM 2.0'
dw 512
db 1
dw 1
db 2
dw 64
dw 360
db 0fch
dw 2
;
;
funtab label byte
dw init
dw media_check
dw build_bpb
dw ioctl_in
dw input
dw nd_input
dw in_stat
dw in_flush
dw output
dw out_verify
dw out_stat
dw out_flush
dw ioctl_out
;
;
in_save proc near
mov ax,es:word ptr dta[bx]
mov cs:user_dta,ax
mov ax,es:word ptr dta+2[bx]
mov cs:user_dta+2,ax
mov ax,es:word ptr count[bx]
xor ah,ah
mov cs:total,ax
ret
in_save endp
;
calc_addr proc near
mov ax,cs:start_sec
mov cx,20h
mul cx
mov dx,cs:vdisk_ptr
add dx,ax
mov ds,dx
xor si,si
mov ax,cs:total
mov cx,512
mul cx
or ax,ax
jnz move_it
mov ax,0ffffh
move_it:
xchg cx,ax
ret
calc_addr endp
;
sector_read proc near
call calc_addr
mov es,cs:user_dta+2
mov di,cs:user_dta
;
mov ax,di
add ax,cx
jnc read_copy
mov ax,0ffffh
sub ax,di
mov cx,ax
read_copy:
rep movsb
ret
sector_read endp
;
sector_write proc near
call calc_addr
push ds
pop es
mov di,si
mov ds,cs:user_dta+2
mov si,cs:user_dta
;
;
mov ax,si
add ax,cx
jnc write_copy
mov ax,0ffffh
sub ax,si
mov cx,ax
write_copy:
rep movsb
ret
sector_write endp
;
dev_strategy:
mov cs:rh_seg,es
mov cs:rh_off,bx
ret
;
;
;
dev_int:
cld
push ds
push es
push ax
push bx
push cx
push dx
push di
push si
;
;
mov al,es:[bx]+2
rol al,1
lea di,funtab
xor ah,ah
add di,ax
jmp word ptr[di]
;
;
init:
push cs
pop dx
lea ax,cs:vdisk
mov cl,4
ror ax,cl
add dx,ax
mov cs:vdisk_ptr,dx
mov ax,2d00h
add dx,ax
mov es:word ptr br_addr_0[bx],0
mov es:br_addr_1[bx],dx
mov es:byte ptr units[bx],1
lea dx,bpb_ptr
mov es:bpb_ptr_off[bx],dx
mov es:bpb_ptr_seg[bx],cs
mov es,cs:vdisk_ptr
xor di,di
lea si,boot_rec
mov cx,24
rep movsb
mov cs:word ptr start_sec,1
mov cs:word ptr total,2
call calc_addr
push ds
pop es
mov di,si
xor al,al
rep stosb
mov ds:byte ptr [si],0fch
mov ds:byte ptr 1[si],0ffh
mov ds:byte ptr 2[si],0ffh
push ds
push si
mov cs:word ptr start_sec,3
mov cs:word ptr total,2
call calc_addr
push ds
pop es
mov di,si
pop si
pop ds
rep movsb
mov cs:word ptr start_sec,5
mov cs:word ptr total,4
call calc_addr
xor al,al
push ds
pop es
xor di,di
rep stosb
mov es,cs:rh_seg
mov bx,cs:rh_off
status done,moerror,0
jmp exit
;
;
media_check:
mov es:byte ptr ret_byte[bx],1
status done,moerror,0
jmp exit
;
;
;
build_bpb:
push es
push bx
mov cs:word ptr start_sec,0
mov cs:word ptr total,1
call calc_addr
push cs
pop es
lea di,bpb
add si,11
mov cx,13
rep movsb
pop bx
pop es
lea dx,bpb
mov es:bpba_ptr[bx],dx
mov es:bpba_ptr+2[bx],cs
mov es:dta[bx],dx
mov es:dta+2[bx],cs
status done,moerror,0
jmp exit
;
;
ioctl_in:
ioctl_out:
nd_input:
in_stat:
in_flush:
out_stat:
out_flush:
;
input:
call in_save
mov ax,es:word ptr ssn[bx]
mov cs:start_sec,ax
mov ax,es:word ptr count[bx]
mov cs:total,ax
call sector_read
mov bx,cs:rh_off
mov es,cs:rh_seg
status done,moerror,0
jmp exit
;
;
output:
call in_save
mov ax,es:word ptr ssn[bx]
mov cs:start_sec,ax
mov ax,es:word ptr count[bx]
mov cs:total,ax
call sector_write
mov bx,cs:rh_off
mov es,cs:rh_seg
cmp cs:byte ptr verify,0
jz no_verify
mov cs:byte ptr verify,0
jmp input
no_verify:
status done,moerror,0
jmp exit
out_verify:
mov cs:byte ptr verify,1
jmp output
;
;
exit:
pop si
pop di
pop dx
pop cx
pop bx
pop ax
pop es
pop ds
ret
e_q_p:
if ($-start) mod 16
org ($-start)+16-(($-start) mod 16)
endif
vdisk equ $
vdsk endp
cseg ends
end begin
