How do you do comparison in assembly?

How do you do comparison in assembly?

In assembly, all branching is done using two types of instruction:

1. A compare instruction, like “cmp”, compares two values. Internally, it does this by subtracting them.
2. A conditional jump instruction, like “je” (jump-if-equal), does a goto somewhere if the two values satisfy the right condition.

Which operation is used when a programmer wants to compare two numbers in assembly language?

As already mentioned, usually the comparison is done through subtraction.

What x86_64 assembly instruction is used to compare the contents of two registers?

Most transfers use the mov instruction, which works between two registers or between registers and memory (but not memory-to-memory). When writing a byte or word into the lower part of a register, mov (and the arithmetic operations) only affect the lower byte or word.

What is int21h?

3 Answers. INT 21H will generate the software interrupt 0x21 (33 in decimal), causing the function pointed to by the 34th vector in the interrupt table to be executed, which is typically an MS-DOS API call. This simply means that you are using function 01h of the Interrupt type 21…

What are comparing numbers?

In math, to compare means to examine the differences between numbers, quantities or values to decide if it is greater than, smaller than or equal to another quantity. Here, for instance, we are comparing numbers.

How to compare two numbers in assembly language?

My assumption is, CMP will compare AL to BL. If AL is smaller, JLE will be true and the code in the part ‘TAG’ will be executed. As you can see AL is not smaller, still, TAG is executed. I solved it. In assembly language.

How to compare elements of two arrays in Assembly?

I need to put 4 arrays in memory, each array has 10 numbers which are the size of one byte. Now, I need to find the way to check if any of the numbers from one string have a pair in another string and if they do I need to put those answers on to stack.

Which is better, an assembly language or an assembler?

“ an assembly language ” is good, because there exists no common assembly language. An assembler is also extremely CPU specific. You have a generic “ cmp ” instruction for your numeric type, cmp is usually for a word. i.e. cmp or icmp integer of some width: signed/unsigned int8 – int512.

Can a C instruction compare two values in registers?

For example, on the TMS9900, the C instruction (unrelated to the C programming language) can compare two values in registers, two values in memory, or some combination. To compare the number in the location HMWK with the number at the location ASGMT, do this: I’m going to guess this is a homework assignment, and has additional requirements.

How to compare two numbers by using an assembly language?

It will set the OF, SF, ZF, AF, PF and CF flags accordingly. “ an assembly language ” is good, because there exists no common assembly language. An assembler is also extremely CPU specific. You have a generic “ cmp ” instruction for your numeric type, cmp is usually for a word. i.e. cmp or icmp integer of some width: signed/unsigned int8 – int512.

How to print a smaller number in Assembly?

MSG1 DB10,13,”ENTER FIRST NUMBER TO COMPARE : $”MSG2 DB10,13,”ENTER SECOND NUMBER TO COMPARE : $”MSG3 DB10,13,”SMALLER NUMBER IS : $”ENDS In Assembly programming, the variable are all defined by bytes only. DB – Define Byte  (Size – 1 Byte)

How to compare two signed numbers in Z80 assembly?

The CP instruction subtracts -4 from 3 as follows: As you can see the carry flag is set indicating that -4 is greater than 3. Which is not what I expect = ( This makes me suspect that the logic in the quote only works for unsigned comparisons. How do you compare two signed numbers in z80 assembly?

How do you compare two numbers in x86?

Most machines offer registers, which have symbolic names like R1, or EAX (the Intel x86), and have instruction names like “CMP” for compare. And for a compare instruction, you need another operand, sometimes a register, sometimes a literal. Often assemblers allow comments to the right of instruction.

What is comparison instruction?

Comparison instructions in PLC are used to test pairs of values to condition the logical continuity of a rung. As an example, suppose a LES instruction is presented with two values. If the first value is less than the second, then the comparison instruction is true.

What does CMP mean in assembly?

Compare Two Operands
Compare Two Operands (cmp) (IA-32 Assembly Language Reference Manual)

Which is the comparison instruction used in PLC?

The LES, also known as the Less Than, is an instruction used to compare two values against each other. The instruction takes two integers, floats or constants and will return TRUE if the value specified in “Source A” is less than the one in “Source B”.

When a subroutine is called the address of the instruction next to call is kept in?

stack
When a subroutine is called, the address of the instruction following the CALL instructions stored in /on the stack. The return address associated with a subroutine is stored in either a processor register or in memory called stack. The program counter then fetches the address of the next instruction from the stack.

What does Beq do in assembly?

BEQ (short for “Branch if EQual”) is the mnemonic for a machine language instruction which branches, or “jumps”, to the address specified if, and only if the zero flag is set.