lpt_pkg.asm

汇编源代码大全2

        ADD	DX,DATREG       ;;; DX equals port to send data to.
        MOV     AL,ES:[BX+DI]   ;;; Get data from buffer.
        OUT     DX,AL           ;;; Put data in output register.
	ADD	DX,(CMDREG-DATREG) ;;; Point to command register.
        MOV     AL,(IRQE+SELECT+INIT+STROBE) ;;; Prepare to strobe data.
	OUT	DX,AL		;;; Set strobe high.
        MOV     AL,(IRQE+SELECT+INIT) ;;;
	OUT	DX,AL		;;; Set strobe low.
        INC     BX              ;;; Increment START_TDATA.
        CMP     BX,[SI].TBUF_SIZE	;;; See if gone past end.
	 JB	NTADJ           ;;; If not then skip.
        XOR     BX,BX		;;; Reset to beginning.
NTADJ:  MOV     [SI].START_TDATA,BX  ;;; Save START_TDATA.
        DEC     [SI].SIZE_TDATA      ;;; One less character in x-mit buffer.
	JMP	REPOLL		;;; Check again is ready for next char.

INT_END:
        POP     DX		;;; Restore previous context.
        POP     CX		;;;
        POP     BX		;;;
        POP     AX		;;;
        POP     DI		;;;
        POP     SI		;;;
        POP     BP		;;;
        POP     ES		;;;
        POP     DS		;;;
        IRET			;;; Return from interrupt.

INT_HNDLR ENDP

	.SBHED	<LPT_INI -- Initialize Communication Port>

; void
; lpt_ini(unit, tbuf, tbuflen, pinit)
;			/* Initializes port and interrupt vector. */
; int unit;		/* 1 ==> LPT1:, 2 ==> LPT2:. */
; char *tbuf;		/* Transmit buffer address. */
; int tbuflen;		/* Transmit buffer length. */
; bool pinit;		/* TRUE ==> force printer initialization. */

;	Initialize the Intel 8250 and set up interrupt vector to int_hndlr.

IF LDATA
	BENTRY	LPT_INI	<UNIT,TBOFF,TBSEG,TBLEN,PINIT>
ELSE
	BENTRY	LPT_INI	<UNIT,TBOFF,TBLEN,PINIT>
ENDIF

        MOV     AX,DS		; Copy our data segment number.
IFE LDATA
	MOV	ES,AX		; Save for buffer addresses.
ENDIF
        MOV     CS:DATASEG,AX	; Store segment # in code space (gulp!).

	MOV	SI,OFFSET LPT1_CTRL ; Setup pointer to control structure.

				; Pickup printer port from BIOS:
        PUSH    DS		; Save current data segment.
        XOR     AX,AX		; Zero AX.
        MOV     DS,AX		; Switch to segment zero.
	MOV	AX,WORD PTR DS:PRINTER_BASE ; Get the printer port.
	POP	DS		; Restore our data segment.
	MOV	[SI].LPTX_BASE,AX	; Save printer base address.

IF LDATA
	MOV	AX,TBSEG	; Get the transmit buffer segment number.
ELSE
	MOV	AX,ES		; Default transmit buffer segment number.
ENDIF
	MOV	[SI].TBUF_SEG,AX	; Save it.
	MOV	AX,TBOFF	; Copy the transmit buffer offset.
	MOV	[SI].TBUF_OFF,AX	;
	MOV	AX,TBLEN	; Copy the transmit buffer length.
	MOV	[SI].TBUF_SIZE,AX	;

	XOR	AX,AX		; Clear the accumulator.
	MOV	[SI].START_TDATA,AX	; Reset start of transmitted data.
	MOV	[SI].END_TDATA,AX	; Reset end of transmitted data.
	MOV	[SI].SIZE_TDATA,AX	; Reset number of transmitted chars.

	CMP	WORD PTR PINIT,0	; Do we want a printer init?
	 JE	NOINIT		;   (nope)
	MOV	DX,[SI].LPTX_BASE	; Get printer base address.
	ADD	DX,CMDREG	; Point to command register.
        MOV     AL,(SELECT)
        OUT     DX,AL		; Start initialization.

	MOV	AX,1000		; Prepare to burn some time.
INILOP:	DEC	AX
	JNZ	INILOP

        MOV     AL,(SELECT+INIT)
        OUT     DX,AL		; Stop initialization.
NOINIT:

				; Setup the LPT interrupt vector:
	MOV	AX,(LPT_INT+INT_OFF)	; Get the LPT: interrupt number.
	MOV	BX,OFFSET INT_HNDLR	; Start of the interrupt routine.
	BCALL	INT_SETU <AX BX CS>	; Call int_setup(vec, newip, newcs).

        CLI			; ******* Disable Interrupts *******

				;;; Enable interrupts on 8259:
        IN      AL,IMR          ;;; Get current enable bits on 8259.
	MOV	CL,LPT_INT	;;; Get interrupt number.
	MOV	BL,1		;;; Convert to
	SHL	BL,CL		;;;   bit position.
	NOT	BL		;;; Clear current
        AND     AL,BL		;;;   interrupt bit.
        OUT     IMR,AL		;;; Set enable on 8259.

        STI			;;; ******* Enable Interrupts *******
				;;; (Next instruction still disabled)
	BEND	LPT_INI

	.SBHED	<LPT_TRM -- Turn Off Interrupts and Shutdown>

; void
; lpt_trm(unit)		/* Turns off interrupts from the LPT: port. */
; int unit;		/* 1 ==> LPT1:, 2 ==> LPT2:. */

	BENTRY	LPT_TRM <UNIT>

	MOV	SI,OFFSET LPT1_CTRL ; Setup pointer to control structure.

	MOV	DX,[SI].LPTX_BASE
	ADD	DX,CMDREG	; Turn off line printer interface.
        MOV     AL,(SELECT+INIT)
        OUT     DX,AL

        IN      AL,IMR		; Turn off 8259 interrupt controller.
	MOV	CL,LPT_INT	; Get interrupt number.
	MOV	BL,1		; Convert to
	SHL	BL,CL		;   bit position.
        OR      AL,BL		; Disable this interrupt.
        OUT     IMR,AL

				; Restore the LPT interrupt vector:
	MOV	AX,(LPT_INT+INT_OFF)	; Get the LPT: interrupt number.
	BCALL	INT_REST <AX>		; Call int_restore(vec).

	BEND	LPT_TRM

	.SBHED	<LPT_OCNT -- Returns Number of Free Bytes>

; int			/* Number of free bytes in output buffer. */
; lpt_ocnt(unit)	/* Returns number of free bytes in output buffer. */
; int unit;		/* 1 ==> LPT1:, 2 ==> LPT2:. */

	BENTRY	LPT_OCNT <UNIT>

	MOV	SI,OFFSET LPT1_CTRL ; Setup pointer to control structure.

        MOV     AX,[SI].TBUF_SIZE	; Get the size of the x-mit buffer.
        SUB     AX,[SI].SIZE_TDATA	; Subtract the number of bytes used.

	BEND	LPT_OCNT

	.SBHED	<LPT_PUTC -- Queue a Character for Output>

; bool			/* Returns FALSE if no more room. */
; lpt_putc(unit, ch)	/* Writes a character to the output buffer. */
; int unit;		/* 1 ==> LPT1:, 2 ==> LPT2:. */
; char ch;		/* The character to write. */


	BENTRY	LPT_PUTC <UNIT,OCHAR>

	MOV	SI,OFFSET LPT1_CTRL ; Setup pointer to control structure.

        MOV     AX,[SI].TBUF_SIZE	; Get the size of the x-mit buffer.
        SUB     AX,[SI].SIZE_TDATA	; Subtract the number of bytes used.
	 JE	L24		; No more free space.

	MOV	ES,[SI].TBUF_SEG	; Get transmit buffer segment number.
	MOV	DI,[SI].TBUF_OFF	; Get transmit buffer offset.
        MOV     BX,[SI].END_TDATA	; BX points to free space.
        MOV     AL,OCHAR        ; Move data from stack to x-mit buffer.
        MOV     ES:[BX+DI],AL
        INC     BX              ; Increment END_TDATA to point to free space.
        CMP     BX,[SI].TBUF_SIZE	; See if past end.
         JB      L20		; If not then skip.
        XOR     BX,BX		; Adjust to beginning.
L20:	MOV     [SI].END_TDATA,BX	; Save new END_TDATA.

        INC     [SI].SIZE_TDATA	; One more character in x-mit buffer.
	MOV	DX,[SI].LPTX_BASE ; Prepare to manipulate printer interrupts.
        ADD	DX,CMDREG	; Point to printer command register.
	IN	AL,DX		; Read command register.
	TEST	AL,IRQE		; Are printer interrupts enabled?
	 JNZ	L22		; Yes, so output is active.
        MOV     AL,(IRQE+SELECT+INIT) ; No, so enable printer interrupts.
        OUT     DX,AL		;
	INT	(LPT_INT+INT_OFF) ; Request an interrupt to start output.
L22:
	MOV	AX,TRUE		; Indicate all's OK.
	JMP SHORT L26		; Go join common return code.

L24:	MOV	AX,FALSE	; No more space in buffer.

L26:	BEND	LPT_PUTC

	.SBHED	<LPT_STAT -- Return Line Printer Hardware Status>

; int			/* Returns printer status bits. */
; lpt_stat(unit)	/* Reads printer hardware status. */
; int unit;		/* 1 ==> LPT1:, 2 ==> LPT2:. */

	BENTRY	LPT_STAT <UNIT>

	MOV	SI,OFFSET LPT1_CTRL ; Setup pointer to control structure.

	MOV	DX,[SI].LPTX_BASE	; Get LPT: base register.
        ADD	DX,STATREG	; Point to status bits.
        IN      AL,DX		; Read the status bits.
	XOR	AH,AH		; Clear high bits.
				; Return result in AX.
	BEND	LPT_STAT

	ENDPS
        END