Source code of Windows XP (NT5)
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412 lines
8.3 KiB

page,132
;---------------------------Module-Header-------------------------------;
; Module Name: IBMLPT.ASM
;
; Copyright (c) Microsoft Corporation 1985-1990. All Rights Reserved.
;
; General Description:
;
; History:
;
;-----------------------------------------------------------------------;
title IBMLpt - IBM PC, PC-XT, PC-AT, PS/2 Parallel Communications Interface
.xlist
include cmacros.inc
include comdev.inc
include ins8250.inc
include ibmcom.inc
.list
sBegin Code
assumes cs,Code
assumes ds,Data
externFP GetSystemMsecCount
externA __0040H
;----------------------------Private-Routine----------------------------;
;
; DoLPT - Do Function To LPT port
;
; The given function (output or reset) is performed to the
; passed LPT port.
;
; Before a character is sent, a check is made to see if the device
; will be able to accept the character. If it can, then the character
; will be sent. If not, then an error will be returned. If the
; printer is selected and busy and no error, then the code returned
; will be CE_TXFULL and the handshake bits will be set in HSFlag
; to simulate that a handshake was received.
;
; If the BIOS ROM code is examined, you will note that they wait for
; the busy character from the last charcater to be cleared before
; they strobe in the current character. This can take a long time
; on the standard EPSON class printer (1 mSec to greater than
; 300 mSec if the last character actually caused printing).
;
; Because of this, several status read retrys will be made before
; declaring that the device is actually busy. If only one status
; read is performed, the spooler will yeild, take a while to get
; back here, and things will be really slow. What difference does
; it really make if we or the BIOS does the delay, at least we can
; break out of it at some point when it seems hopeless.
;
; The OKIHACK: Okidata reports a 50 ns. 2.2 volt pulse on the paper
; out signal on the trailing edge of the Busy signal. If we see this
; glitch then we report paper out. So we try to get the status twice...
; if it changes between the two tries we keep getting the status.
;
;
; Entry:
; AH = cid
; AL = character to output
; CH = Function request. 0 = Output, 1 = Initialize, 2 = Status
; DS:SI -> DEB for the port
; Returns:
; AX = 0 if no errors occured
; Error Returns:
; AX = error code
; Registers Preserved:
; SI,DI
; Registers Destroyed:
; AX,BX,CX,DX,ES,FLAGS
; History:
;-----------------------------------------------------------------------;
assumes ds,Data
assumes es,nothing
public DoLPT
DoLPT proc near
mov dx,Port[si] ;Get port address
; DX = port address
; CH = operation: 0 = write, 1 = init, 2 = status
; AL = character
or ch, ch
jz LPT_OutChar
cmp ch, 1
jz LPT_Reset
jmp LPT_GetStatus
ret
LPT_Reset:
inc dx
inc dx
mov al, L_RESET
iodelay
out dx, al
push dx
cCall GetSystemMsecCount
mov bx, ax
LPT_ResetDelay:
push bx
cCall GetSystemMsecCount
pop bx
sub ax, bx
cmp ax, 300 ; 1/3 sec as good as any
jbe LPT_ResetDelay
pop dx
mov al, L_NORMAL
iodelay
iodelay
out dx, al
dec dx
dec dx
jmp LPT_GetStatus
LPT_OutChar:
push ax ; save character to be written
; first check to see if printer is ready for us
push di
push dx
call GetSystemMSecCount
mov di, ax
pop dx
LPT_WaitReady:
inc dx ; point to status port
iodelay
in al, dx ; get status bits
and al, L_BITS ; mask unused ones
xor al, L_BITS_INVERT ; flip a couple
xchg al, ah
ifndef NOOKIHACK
iodelay
in al, dx
dec dx
and al, L_BITS
xor al, L_BITS_INVERT
cmp al, ah ; did any bits change?
jnz LPT_WaitReady
else
dec dx
endif
test ah, PS_PaperOut or PS_IOError
jnz LPT_PrinterNotReady
test ah, PS_Select
jz LPT_PrinterNotReady
test ah, PS_NotBusy
jnz LPT_PrinterReady
push ax
push dx
call GetSystemMSecCount
pop dx
pop bx
sub ax, di
cmp ax, 300 ; 1/3 sec timeout
jbe LPT_WaitReady
; The device seems to be selected and powered up, but is just
; busy (some printers seem to show selected but busy when they
; are taken offline). Show that the transmit queue is full and
; that the hold handshakes are set. This is so the windows
; spooler will retry (and do yields so that other apps may run).
or ComErr[si],CE_TXFULL ;Show queue full
mov ah,bh
or ah, L_TIMEOUT
LPT_PrinterNotReady:
pop di
pop cx ; throw away character
jmp short LPT_ReturnStatus
LPT_PrinterReady:
pop di ; get di back
pop ax ; get character back
iodelay
out dx, al ; write character to port
inc dx ; access status port
LPT_Strobe:
inc dx ; control port
mov al, L_STROBE ; set strobe high
iodelay
iodelay
iodelay
iodelay
out dx, al ; ...
mov al, L_NORMAL ;
iodelay
iodelay
iodelay
iodelay
out dx, al ; set strobe low
sub dx, 2 ; point back to port base
; FALL THRU
LPT_GetStatus:
inc dx ; point to status port
LPT_GS1:
iodelay
iodelay
in al, dx ; get status bits
and al, L_BITS ; mask unused ones
xor al, L_BITS_INVERT ; flip a couple
mov ah, al
ifndef NOOKIHACK
in al, dx
and al, L_BITS
xor al, L_BITS_INVERT
cmp al, ah
jnz LPT_GS1 ; if they changed try again...
endif
LPT_ReturnStatus:
assumes ds,Data
and ax,(PS_PaperOut+PS_Select+PS_IOError+PS_Timeout)*256
shr ah,1
adc ah,al ;Get back Timeout bit
xor ah,HIGH CE_DNS ;Invert selected bit
.errnz LOW CE_DNS
or by ComErr+1[si],ah ;Save comm error
ret
.errnz CE_PTO-0200h
.errnz CE_IOE-0400h
.errnz CE_DNS-0800h
.errnz CE_OOP-1000h
DoLPT40:
assumes ds,Data
or ComErr[si],CE_TXFULL ;Show queue full
ret
DoLPT endp
page
CheckStatus proc near
in al, dx ; get status bits
mov ah, al
and al, L_BITS ; mask unused ones
xor al, L_BITS_INVERT ; flip a couple
xchg al, ah
ifndef NOOKIHACK
iodelay
in al, dx
and al, L_BITS
xor al, L_BITS_INVERT
cmp al, ah ; did any bits change?
jnz CheckStatus
endif
test ah, PS_PaperOut or PS_IOError
jz @F
stc
ret
@@:
test ah, PS_Select
jnz @F
stc
ret
@@:
and ah, PS_NotBusy
clc
ret
CheckStatus endp
;----------------------------Public Routine-----------------------------;
;
; StringToLPT - Send string To LPT Port
;
; Entry:
; DS:SI -> DEB
; ES:DI -> string to send
; CX = # of bytes to send
; Returns:
; AX = # of bytes actually sent
; Registers Destroyed:
; AX,BX,CX,DX,ES,FLAGS
; History:
;-----------------------------------------------------------------------;
PUBLIC StringToLPT
StringToLPT proc near
mov dx, Port[si] ; get port address
inc dx ; access status port
push cx ; save count for later
push ds
mov bx, __0040H
mov ds, bx
cld
call CheckStatus ; quick status check before slowness
jc PrinterError
jz PrinterBusy ; if printer not ready for first char
; then just return with CE_TXFULL
CharacterToLPT:
;; mov bh, 10 ; will wait 10 clock tics (~ 1/2 sec)
mov bh, 3 ; will wait 3 clock tics (~ 1/6 sec)
l1:
mov bl, ds:[006Ch] ; low byte of tic counter
l2:
call CheckStatus ; quick status check before slowness
jc PrinterError
jnz LPT_PrinterRdy
cmp bl, ds:[006Ch]
jz l2 ; tic count hasn't changed
dec bh
jz PrinterBusy ; out of tics, timeout
jmp short l1
LPT_PrinterRdy:
mov al, es:[di]
inc di
dec dx ; point to data port
out dx, al ; write character to port
add dx, 2 ; access control port
mov al, L_STROBE ; set strobe high
out dx, al ; ...
mov al, L_NORMAL ;
iodelay
iodelay
out dx, al ; set strobe low
dec dx ; point to status port for check
loop CharacterToLPT
pop ds
jmp short LPT_Exit
PrinterError:
pop ds
jmp short ReturnStatus
PrinterBusy:
pop ds
or ComErr[si],CE_TXFULL ; set buffer full bit
or al, L_TIMEOUT ; show timeout bit
ReturnStatus:
and ax,(PS_PaperOut+PS_Select+PS_IOError+PS_Timeout)
xchg al, ah
shr ah,1
adc ah,al ;Get back Timeout bit
xor ah,HIGH CE_DNS ;Invert selected bit
.errnz LOW CE_DNS
or by ComErr+1[si],ah ;Save comm error
LPT_Exit:
pop ax ; get total count
sub ax, cx ; subtract remaining unsent charts
ret
StringToLPT endp
IFDEF DEBUG ;Publics for debugging
public LPT_Reset
public LPT_Outchar
public LPT_Strobe
public LPT_GetStatus
public DoLPT40
ENDIF
sEnd code
End