Question

5) Mutually assured instruction. (10 pts) a) First, deduce the following functions. (4pts) 000000000000064a <func1>: 64a: 48 83 ec 18 sub $0x18,%rsp 64e: 89 70 24 OC mov %edi, oxc(%rsp) 652: 83 70 24 Oc 00 cmpl $0x0, xc(%rsp) 657: 75 07 jne 660 <func1+0x16> 659: b8 01 00 00 00 mov $0x1,%eax 65e: ebbe jmp 66e <func1+0x24> 660: 85 44 24 Oc mov Oxc(%rsp), %eax 664: 83 e8 01 sub $0x1, %eax 667: 89 c7 mov %eax, %edi 669: 8 05 00 00 00 callq 673 <func2> 66e: 48 83 c4 18 add $0x18,%rsp 672: C3 reta int func1(unsigned int n) { if ( n == 0 ) return 1; else return func2(n-1); int func2(unsigned int n) { if ( n == 0 ) return 0; else return func1(n-1); 0000000000000673 <func2>: 673: 48 83 ec 18 677: 89 70 24 OC 67b: 83 7c 24 Oc 00 680: 75 07 682: b8 00 00 00 00 687: eb De 689: 85 44 24 Oc 68d: 83 e8 01 690: 89 c7 692: e8 b3 ff ff ff 697: 48 83 c4 18 69b: c3 sub $0x18,%rsp mov %edi, oxc(%rsp) cmpl $0x0, xc(%rsp) jne 689 <func2+0x16> mov $0x0,%eax jmp 697 <func2+0x24> mov exc(%rsp), %eax sub $0x1, %eax mov %eax, %edi callq 64a <func1> add $0x18,%rsp reta

Please explain the table solution. The red answers are correct. Please explain step by step why

Answer 1

The following Code is the operation done in Assembly Language. We are using simple push and pop with a different function

Let's learn about stack first Stack is a kind of memory that stores values provided the value can be removed or added accordingly. Now Stack works in 2 processes:-

1:LIFO( Last IN First Out)We can push the value from the last and remove a value ie pop from first

2.FILO(First In Last Out) We can push from the upper part of the stack and remove from the last part

Now register

The register is nothing but storage of the CPU what it does is it can store an instruction or any kind of data.

Lets first understand what does different function does

Data Movement

1. mov: this instruction copies the data item referred to ie. Register contents, memory contents etc.

(Arithmetic Instruction)

2.sub-Integer subtraction ---- The sub instruction stores the first operand value which is intern the result of the subtraction of second operand and the first operand.

3. add- This function stores the addition of two operands in its first operands

(Control Flow Instruction)

4.jmp: Jump function---it Transfers the control function to the instruction to the memory location which is mentioned in the instruction

5.jne: This is the same as a jump but j-Function also provides certain condition so jne jumps when it compares the previous operand and the given operand and it is not equal.

6.cmp-Compares the 2 operands

Now in the stack Unused is the part where the stack is empty and no address is saved rest is the address which is being stored.

Hope it explain you the code