How To Register A Car If Title Jumped

Assembly - Conditions

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Conditional execution in assembly language is accomplished by several looping and branching instructions. These instructions tin change the catamenia of control in a program. Conditional execution is observed in two scenarios −

Sr.No.	Conditional Instructions
one	Unconditional jump This is performed by the JMP pedagogy. Conditional execution ofttimes involves a transfer of control to the address of an instruction that does not follow the currently executing instruction. Transfer of control may be forward, to execute a new gear up of instructions or backward, to re-execute the same steps.
2	Conditional jump This is performed by a set of bound instructions j<condition> depending upon the condition. The conditional instructions transfer the control past breaking the sequential menstruation and they do information technology by changing the outset value in IP.

Permit us discuss the CMP instruction earlier discussing the provisional instructions.

CMP Instruction

The CMP instruction compares two operands. It is generally used in conditional execution. This instruction basically subtracts 1 operand from the other for comparison whether the operands are equal or not. It does non disturb the destination or source operands. It is used along with the conditional jump instruction for determination making.

Syntax

CMP destination, source        

CMP compares two numeric data fields. The destination operand could exist either in register or in retentiveness. The source operand could be a constant (immediate) data, register or retention.

Instance

CMP DX,	00  ; Compare the DX value with zero JE  L7      ; If yes, then spring to label L7 . . L7: ...        

CMP is ofttimes used for comparing whether a counter value has reached the number of times a loop needs to be run. Consider the post-obit typical condition −

INC	EDX CMP	EDX, 10	; Compares whether the counter has reached x JLE	LP1     ; If it is less than or equal to ten, and then leap to LP1        

Unconditional Jump

As mentioned before, this is performed by the JMP didactics. Provisional execution oftentimes involves a transfer of command to the accost of an education that does not follow the currently executing teaching. Transfer of command may be forwards, to execute a new set up of instructions or backward, to re-execute the aforementioned steps.

Syntax

The JMP instruction provides a characterization name where the flow of command is transferred immediately. The syntax of the JMP educational activity is −

JMP	characterization        

Instance

The post-obit lawmaking snippet illustrates the JMP didactics −

MOV  AX, 00    ; Initializing AX to 0 MOV  BX, 00    ; Initializing BX to 0 MOV  CX, 01    ; Initializing CX to 1 L20: ADD  AX, 01    ; Increase AX ADD  BX, AX    ; Add AX to BX SHL  CX, 1     ; shift left CX, this in turn doubles the CX value JMP  L20       ; repeats the statements        

Provisional Leap

If some specified condition is satisfied in conditional jump, the control menstruation is transferred to a target instruction. There are numerous provisional bound instructions depending upon the condition and information.

Following are the provisional spring instructions used on signed data used for arithmetics operations −

Instruction	Clarification	Flags tested
JE/JZ	Bound Equal or Spring Naught	ZF
JNE/JNZ	Bound not Equal or Spring Non Zero	ZF
JG/JNLE	Jump Greater or Jump Non Less/Equal	OF, SF, ZF
JGE/JNL	Jump Greater/Equal or Leap Non Less	OF, SF
JL/JNGE	Leap Less or Jump Non Greater/Equal	OF, SF
JLE/JNG	Jump Less/Equal or Spring Non Greater	OF, SF, ZF

Following are the conditional jump instructions used on unsigned data used for logical operations −

Instruction	Description	Flags tested
JE/JZ	Jump Equal or Bound Zero	ZF
JNE/JNZ	Jump not Equal or Leap Not Zero	ZF
JA/JNBE	Jump Above or Jump Not Below/Equal	CF, ZF
JAE/JNB	Jump Above/Equal or Jump Not Beneath	CF
JB/JNAE	Jump Below or Leap Not Above/Equal	CF
JBE/JNA	Bound Beneath/Equal or Leap Not Above	AF, CF

The post-obit conditional jump instructions accept special uses and check the value of flags −

Instruction	Description	Flags tested
JXCZ	Leap if CX is Cypher	none
JC	Spring If Acquit	CF
JNC	Leap If No Carry	CF
JO	Jump If Overflow	OF
JNO	Bound If No Overflow	OF
JP/JPE	Spring Parity or Jump Parity Even	PF
JNP/JPO	Spring No Parity or Jump Parity Odd	PF
JS	Jump Sign (negative value)	SF
JNS	Jump No Sign (positive value)	SF

The syntax for the J<status> set of instructions −

Instance,

CMP	AL, BL JE	EQUAL CMP	AL, BH JE	EQUAL CMP	AL, CL JE	EQUAL NON_EQUAL: ... EQUAL: ...        

Example

The following program displays the largest of iii variables. The variables are double-digit variables. The three variables num1, num2 and num3 accept values 47, 22 and 31, respectively −

section	.text    global _start         ;must be declared for using gcc  _start:	                 ;tell linker entry point    mov   ecx, [num1]    cmp   ecx, [num2]    jg    check_third_num    mov   ecx, [num2]     	check_third_num:     cmp   ecx, [num3]    jg    _exit    mov   ecx, [num3]     	_exit:        mov   [largest], ecx    mov   ecx,msg    mov   edx, len    mov   ebx,1	;file descriptor (stdout)    mov   eax,4	;system call number (sys_write)    int   0x80	;telephone call kernel 	    mov   ecx,largest    mov   edx, ii    mov   ebx,one	;file descriptor (stdout)    mov   eax,4	;system phone call number (sys_write)    int   0x80	;phone call kernel         mov   eax, 1    int   80h  section	.data        msg db "The largest digit is: ", 0xA,0xD     len equ $- msg     num1 dd '47'    num2 dd '22'    num3 dd '31'  segment .bss    largest resb 2        

When the in a higher place code is compiled and executed, it produces the post-obit result −

The largest digit is:  47        

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Source: https://www.tutorialspoint.com/assembly_programming/assembly_conditions.htm

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