Transcript Lab Work 2
MICROPROCESSOR INTRODUCTION TO ASSEMBLY PROGRAMMING LANGUAGE Yrd. Doç. Dr. Abdül Kadir Görür Uğur Sopaoğlu REGISTERS • REGISTERS CAN BE GROUPED INTO GENERAL, CONTROL AND SEGMENT REGISTERS • GENERAL REGISTERS • DATA REGISTER : AX, BX,CX, DX => 16 BITS • POINTER AND INDEX REGISTERS: SI, DI, SP, BP • CONTROL REGISTERS • INSTRUCTION POINTER REGISTER AND FLAG REGISTER • STATUS FLAG REGISTERS => CARRY FLAG (CF), PARITY FLAG (PF), AUXILIARY FLAG(AF), ZERO FLAG (ZF), SIGN FLAG(SF), OWERFLOW FLAG (OF) • CONTROL FLAGS => DIRECTION FLAG(DF) • SYSTEM FLAGS => TF, IF, IOPL, NT, RF, VM, AC, VIF, VIP, ID REGISTERS • SEGMENT REGISTERS • CODE SEGMENT REGISTER(CS) • DATA SEGMENT REGISTER(DS) • STACK SEGMENT REGISTER(SS) • ES, GS AND FS ( ADDITIONAL SEGMENT REGISTERS) • LABEL MNEMONIC OPERAND COMMENT --------------------------------------------------------.DATA EXCODE DB 0 ;A BYTE VARIABLE MYWORD DW ? ;UNINITIALIZED WORD VAR. .CODE MAIN PROC MOV AX,@DATA ;INITIALIZE DS TO ADDRESS MOV DS,AX ; OF DATA SEGMENT JMP EXIT ;JUMP TO EXIT LABEL MOV CX,10 ;THIS LINE SKIPPED! EXIT: MOV AH,04CH ;DOS FUNCTION: EXIT PROG MOV AL, EXCODE ;RETURN EXIT CODE VALUE INT 21H ;CALL DOS. TERMINATE PROG MAIN ENDP ;END PROGRAM END MAIN ; AND SPECIFY ENTRY POINT DATA ALLOCATION • DATA CAN BE DECLARED WITH FOLLOWING SIZE • DB DEFINE BYTE => 1 BYTE • DW DEFINE WORD=> 2 BYTES • DD DEFINE DOUBLEWORD=> 4 BYTES • DQ DEFINE QUADWORD=>8 BYTES(EMU8086 DOES NOT SUPPORT) • DT DEFINE TEN BYTES=> 10 BYTES(EMU8086 DOES NOT SUPPORT) EXAMPLES • SORTED DB ‘Y’ • SORTED DB ? => UNINITIALIZED VARIABLE • VALUE DW 251 • VALUE DW -251 => YOU CAN ALSO ASSIGN NEGATIVE VALUES WE CAN GENERALLY USE DD AND DQ DIRECTIVES TO ASSIGN REAL NUMBERS FLOAT DD 1.234 REAL DQ 123.456 MULTIPLE DEFINITION AND INITIALIZATIONS • MESSAGE DB ‘WELCOME!’ • MARKS DB 0,1,1,0,0,0,0,1,1,0 • MARKS DB 10 DUP(0) • MARKS DB 10(?) • MARKS DB 10(‘?’) CORRESPONDENCE TO C TYPES INVALID MOV OPERATIONS • MOV DL, CX DIFFERENT OPERAND SIZES • MOV DS, 175 IMMEDIATE VALUE CAN NOT BE MOVED INTO A SEGMENT REGISTER • MOV 715, AX IMMEDIATE VALUE CAN NOT BE DESTINATION OPERAND • MOV ES, DS BOTH REGISTER CAN NOT BE SEGMENT REGISTERS • MOV CS, ES BOTH REGISTER CAN NOT BE SEGMENT REGISTERS AMBIGUOUS MOVES: PTR DIRECTIVE • MOV BX, OFFSET TABLE1 • MOV [BX],100 • THIS OPERATION IS NOT A CLEAR • MOV WORD PTR [BX], 100 • PTR DIRECTIVE CAN BE USED TO CLARIFY • INC [BX] AND DEC [BX] • THESE OPERATIONS ARE AMBIGUOUS • INC WORD PTR [BX] AND DEC WORD PTR [BX] ADD, SUB AND CMP • ADD DESTINATION, SOURCE • ADD AX,BX => AX = AX + BX • SUB DESTINATION, SOURCE • SUB AX,BX => AX = AX-BX • CMP (COMPARE) INSTRUCTION IS USED TO COMPARE TWO OPERANDS. THE CMP INSTRUCTION THE PERFORMS SAME OPERATION AS THE SUB EXCEPT THAT THE RESULT OF SUBTRACTION IS NOT SAVED • NOT IS USED TO TAKE ONE’S COMPLEMENT OF ANY NUMBER • NEG IS USED TO TAKE TWO’S COMPLEMENT OF ANY NUMBER JUMP OPERATION • UNCONDITIONAL JUMP • • MOV AX, 1 INC_AGAIN: • INC AX • JMP INC_AGAIN • CONDITIONAL JUMP • • MOV AX,4 • INC AX • CMP AX,5 • JE A A: JUMP OPERATION • JE JUMP IF EQUAL • JG JUMP IF GREATER • JL JUMP IF LESS • JGE JUMP IF GREATER THAN OR EQUAL • JLE JUMP IF LESS THAN OR EQUAL • JNE JUMP IF NOT EQUAL ITERATION INSTRUCTION(LOOP) • MOV CL,50 • REPEAT: • <LOOP BODY> • DEC CL • JNZ REPEAT LOGICAL INSTRUCTIONS • AND DESTINATION, SOURCE • OR DESTINATION, SOURCE • NOT DESTINATION • HOW CAN WE CHECK THE VALUE OF SIGN BIT? SHIFT INSTRUCTION • SHIFT LEFT(SHL) OR SHIFT RIGHT(SR) CAN BE USED • SHL DESTINATION, COUNT • SHR DESTINATION, COUNT MOV AX,001100 SHL AX,2 => NEW VALUE OF AX = 110000 ROTATE INSTRUCTIONS • ROTATE WITHOUT CARRY • ROTATE LEFT(ROL), ROTATE RIGHT(ROR) • ROL DESTINATION, COUNT • MOV AL, 1010 1110B • ROL AL,1 => THE NEW VALUE OF AL : 0101 1101B • MOV AL, 10101110B • ROR AL,1 = THE NEW VALUE OF AL: 0101 0111B ROTATE INSTRUCTIONS • ROTATE THROUGH CARRY • INSTRUCTIONS RCL AND RCR INCLUDE THE CARRY FLAG IN THE ROTATION PROCESS. • MOV AL, 1010 1110B • RCL AL,1 => THE NEW VALUE OF AL: 0101 1100 • RCR AL,1 => THE NEW VALUE OF AL: 11010111 • BUT IN EMU8086, THERE IS NO DIFFERENCE BETWEEN ROR – RCR AND ROL-RCL DEFINING CONSTANT • TO DEFINE CONSTANT NUMERIC OR STRING, EQU DIRECTIVE IS USED • NAME EQU EXPRESSION • FOR EXAMPLE; • NUM_OF_STUDENTS EQU 90 • IF ANY VALUE IS DEFINED WITH EQU, THE VALUE CAN NOT BE CHANGED DURING THE PROGRAM • ALSO IT CAN BE USED AS MNEMONIC : • JUMP EQU JMP QUESTION • WRITE AN ASSEMBLY PROGRAM. IN THE PROGRAM, YOU MUST DEFINE A WORD ARRAY SIZE OF 10. INITIAL VALUE OF THE EACH ITEM OF ARRAY IS ZERO. THEN, IN THE PROGRAM, CHANGE THE VALUE OF ARRAY ITEM FROM 0 TO 9. FINALLY FIND THE SUMMATION OF ITEM WHOSE LEAST SIGNIFICANT BIT IS ZERO.