2013-08-26: Systems programming lab assignment.

assignment.asm

TITLE Lab05: Read array of integers and display recurring elements

.MODEL SMALL

.STACK 100H

.DATA

	CR EQU 13
	LF EQU 10
	ARR DW 200 DUP(?)
	N DW 0
	HALF DW 0
	SEP DB ", $"
	LIM DB 10, 13, "How many elements? $"
	START_STMT DB 10, 13, "Input array element: $"
	OUT_STMT DB 10, 13, 10, 13, "Output: $"
	NON_NUM DB 10, 13, "Non integer input detected.$"

.CODE

MAIN PROC

	MOV AX, @DATA
	MOV DS, AX
	XOR CX, CX
	LEA DX, LIM
	LEA SI, N
	MOV AH, 9
	INT 21H
	CALL INDEC
	MOV CX, AX
	MOV [SI], CX
	MOV BX, 2
	XOR DX, DX
	DIV BX
	LEA DI, HALF
	MOV [DI], AX
	LEA SI, ARR
    READ_INP:
	LEA DX, START_STMT
	MOV AH, 9
	INT 21H
	CALL INDEC
	MOV [SI], AX
	ADD SI, 2
    LOOP READ_INP
	LEA DI, HALF
	MOV DX, [DI]
	LEA SI, ARR
	LEA DI, N
	MOV CX, [DI]
    TO_END:
	MOV AX, [SI]
	CALL COUNTING
	DEC CX
	CMP BX, DX
      JGE FOUND
	ADD SI, 2
	CMP CX, 0
      JNLE TO_END
    JMP LEAVING
    FOUND:
	LEA DX, OUT_STMT
	PUSH AX
	MOV AH, 9
	INT 21H
	POP AX
	CALL NEWLINE
	CALL OUTDEC
	ADD SI, 2
    JMP TO_END
    LEAVING:
	MOV AH, 76
	INT 21H

MAIN ENDP

COUNTING PROC
	;;  Input:
	;; SI => current array index
	;; AX => element to count
	;; CX => size of array
	;;  Output:
	;; BX => count of element
	PUSH AX
	PUSH CX
	PUSH SI
	XOR BX, BX
	SUB SI, 2
    CUSTOM:
	DEC CX
	CMP CX, 0
      JLE QUITTING
	ADD SI, 2
	CMP AX, [SI]
      JNE CUSTOM
	INC BX
	CMP CX, 0
      JNLE CUSTOM
    QUITTING:
	POP SI
	POP CX
	POP AX
    RET

COUNTING ENDP

	INCLUDE INDEC.ASM
	INCLUDE OUTDEC.ASM
	INCLUDE NEWLINE.ASM

END MAIN

indec.asm

INDEC PROC
	;; Reads a decimal integer
	;; and stores the value in
	;; AX. Requires a string
	;; under .DATA named as
	;; `NON_NUM`

	PUSH BX
	PUSH DX
	XOR BX, BX
	XOR AX, AX
    READ:
	MOV AH, 1
	INT 21H
	CMP AL, CR
      JE END_READ
	CMP AL, LF
      JE END_READ
	CMP AL, '0'
      JNGE NON_INTEGER
	CMP AL, '9'
      JNLE NON_INTEGER
    MY_LOOP:
	AND AX, 000FH
	PUSH AX
	MOV AX, 10
	MUL BX
	POP BX
	ADD BX, AX
    JMP READ
    END_READ:
	MOV AX, BX
	POP DX
	POP BX
    RET
    NON_INTEGER:
	LEA DX, NON_NUM
	MOV AH, 9
	INT 21H
    JMP READ

INDEC ENDP

newline.asm

NEWLINE PROC

	PUSH AX
	PUSH DX
	MOV DL, 0AH
	MOV AH, 2
	INT 21H
	MOV DL, 0DH
	INT 21H
	POP DX
	POP AX
    RET

NEWLINE ENDP

outdec.asm

OUTDEC PROC

        PUSH AX
        PUSH BX
        PUSH CX
        PUSH DX
        OR AX, AX
      JGE QUIT
	PUSH AX
	MOV DL, '-'
	MOV AH, 2
	INT 21H
	POP AX
        NEG AX
    QUIT:
        XOR CX, CX
        MOV BX, 10
    REPEAT:
        XOR DX, DX
        DIV BX
        PUSH DX
        INC CX
        CMP AX, 0
      JNE REPEAT
        MOV AH, 2
    PRINT:
        POP DX
        ADD DL, '0'
        INT 21H
    LOOP PRINT

        POP DX
        POP CX
        POP BX
        POP AX
    RET

OUTDEC ENDP