ECE 330
Due: 2/9/2011
Homework 3
Spring 2011
1. Create macros that implement the following instructions. These macros should not use
any registers other than those specified as operands.
a.
decr
decrement
Operation:
Assembler Syntax:
Example:
b.
rA ← rA - 1
decr rA
decr r6
rori
rotate right immediate
Operation:
Assembler Syntax:
Example:
c.
rB ← rA rotated right IMM5 bit positions
rori rB, rA, IMM5
rori r6, r7, 3
halt
halt execution
Operation:
Assembler Syntax:
Example:
d.
PC ← PC
halt
halt
comp
one’s complement
Operation:
Assembler Syntax:
Example:
rB
←
~rA
comp rB, rA
comp r2, r8
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ECE 330
Due: 2/9/2011
Homework 3
Spring 2011
2. For the memory and registers shown below, show the values for registers that change with each
single step of execution. Make sure that you show the value of the program counter (pc) for
each step. Values must be shown in hexadecimal notation.
Registers
pc
zero
r1
r2
r3
r4
r5
r6
r7
r8
r9
r10
r11
r12
r13
r14
r15
r16
r17
r18
r19
r20
r21
r22
r23
et
bt
gp
sp
fp
ea
ba
ra
status
estatus
bstatus
ienable
ipending
cpuid
Step 0
Step 1
Step 2
0x00000000
0x00000000
0x00000000
0x0000000C
0x00000030
0x00000044
0x0000FFFC
0x000186A0
0x0001E242
0x0000005C
0x00000066
0x000015B2
0x0000092A
0x00004000
0x00002000
0x00000152
0x0001234A
0x0001234C
0x00000048
0x35363738
0x000004D2
0x0000162E
0x000022B8
0x0000115C
0x000008AE
0x00000000
0xFFFFFFFF
0x00000000
0x00000000
0x00000000
0x00000000
0xFFFFFFFF
0x00000000
0x00000000
0x00000000
0xFFFFFFFF
0x00000000
0x00000000
0x00000000
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Step 3
Step 4
Step 5
Step 6
ECE 330
Due: 2/9/2011
Homework 3
Spring 2011
3. For the assembly code, memory and registers shown below, answer the following questions.
# file: hw3_3.s
.text
.global _start
_start:
movia
ldw
r8,COUNT
r8,0(r8)
movia
r9,LIST
mov
r2,r0
LOOP:
beq
r8,r0,LOOP_END
ldw
add
subi
addi
r3,0(r9)
r2,r2,r3
r8,r8,1
r9,r9,4
br
LOOP
LOOP_END:
movia
r9,SUM
stw
r2,0(r9)
br
.
.data
.word
0xaaaaaaaa
COUNT:
.word
(LIST_END-LIST)/4
LIST:
.word
2,3,5,7,11,13,17
LIST_END:
SUM:
.word
0
.word
0xffffffff
.end
a.
What is the value of the label LOOP?
__________
b.
What is the value of the label LOOP_END?
__________
c.
What is the value of the label COUNT?
__________
d.
What is the value of the label LIST?
__________
e.
What is the value of the label LIST_END?
__________
f.
What is the value of the label SUM?
__________
g.
What is the next assembly instruction to be executed?
__________
h.
What is the memory address referenced by the label COUNT?
__________
i.
What is the value of memory (word) referenced by the label COUNT?
__________
j.
What is the address of memory that will change as a result of running this program?
__________
k.
What is the new value (word) in memory that changes?
__________
l.
What is the machine instruction referenced by the label LOOP?
__________
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