CS350 Intro Computer Systems Homework 4

Homework 4 Basic Assembly Instructions

1. Following the style of Practice Problem 3.1 (page.182), assume the following values are stored at the indicated memory addresses and registers:

   Address	Value	--	Register	Value
   0x1000	0xAA	--	%rdi	0x1000
   0x1004	0xBB	--	%rsi	0x1
   0x1008	0xCC	--	%rdx	0x2
   0x100C	0xDD	--	%rcx	0x4

   Fill in the following table showing the values for the indicated operands:

   Operand	Value
   %rdi
   0x1004
   $0x1008
   (%rdi)
   4(%rdi)
   8(%rdi,%rcx)
   0x1002(%rdx,%rcx)
   -4(%rdi,%rsi,4)
   (%rdi,%rdx,4)

2. Using the Address and Register table in Problem 1, fill in the table below showing the values for the indicated operands (similar to Practice Problem 3.8 of page 194):

   Instruction	Destination	Value
   addq (%rdi),%rsi
   andq %rsi,%rdi
   subq %rsi,(%rdi)
   incq %rsi
   decq %rdx
   xorq (%rdi,%rdx,4),%rcx
   orq 0x1002(%rdx,%rcx),%rsi

3. For the unknown assembly shown below, fill in the missing return statement in the C function unknown.

     unknown:
   	imulq	%rdx, %rsi
   	leaq	(%rsi,%rdi), %rax
   	ret
   
     long unknown(long x, long y, long z) {
           return ____________________________;
     }
     

     unknown:
   	movq	%rdi, %rax
   	salq	$3, %rax
   	addq	%rdi, %rax
   	ret
   
     long unknown(long x) {
           return ____________________________;
     }
     

4. Do problem 3.58 which says "Write C code for the assembly shown in the problem."
5. Write an assembly program to perform the C function below using the following register assignment:
   x:rdi; y:rsi, z:rdx, t1:rcx, t2:rdi, t3:rsi, t4:rax
   No credit will be given to the ones with stack addresses.

   long arith(long x, long y, long z) {
     long t1,t2,t3,t4;
     t1 = x + y;
     t2 = t1 - z;
     t3 = t1 & t2;
     t4 = t2 * t3;
   
     return t4;
   }