Chapter 3.9, Problem 3.42PP

A.

Explanation of Solution

Given assembly code:

long fun(struct ELE *ptr)

ptr in %rdi

fun:

movl $0, %eax            

jmp .L2;

.L3:

addq (%rdi), %rax

movq 8(%rdi), %rdi

.L2:

testq %rdi, %rdi

jne .L3

rep;ret

Data movement instructions:

• The different instructions are been grouped as “instruction classes”.
• The instructions in a class performs same operation but with different sizes of operand.
• The “Mov” class denotes data movement instructions that copy data from a source location to a destination.
• The class has 4 instructions that includes:
  • movb:
    • It copies data from a source location to a destination.
    • It denotes an instruction that operates on 1 byte data size.
  • movw: 
    • It copies data from a source location to a destination.
    • It denotes an instruction that operates on 2 bytes data size.
  • movl:
    • It copies data from a source location to a destination.
    • It denotes an instruction that operates on 4 bytes data size.
  • movq:
    • It copies data from a source location to a destination.
    • It denotes an instruction that operates on 8 bytes data size.

Unary and Binary Operations:

• The details of unary operations includes:
  • The single operand serves as both source as well as destination.
  • It can either be a register or a memory location.
  • The instruction “incq” causes 8 byte element on stack top to be incremented.
  • The instruction “decq” causes 8 byte element on stack top to be decremented.
• The details of binary operations includes:
  • The first operand denotes the source...

B.

Explanation of Solution

Data structure implementation and operation performed by fun:

• Each of the structure denotes an element in a singly linked list...