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CS501 Advance Computer Architecture Assignment 2 Solution Fall 2012

In assignment # 1 you were asked to write an SRC assembly language program to evaluate the given expression i.e. f = 4(k+32) + 16(g-h)

 

The sequence of instructions is given and you need to find out the hexadecimal memory contents of all the instructions in the given table except which is not required, accordingly.

 

Label Address Value
k 300 Unknown
g 302 Unknown
h 304 Unknown
f 306 Unknown
Memory Address Memory

Contents

Hexadecimal Memory Contents
400 ld R1,g

 

 
402 ld R2,h

 

Not Required

404 sub R3,R1,R2

 

 
406 shl R7,R3,4

 

 
408 ld R4,k

 

Not Required

410 addi R6,R4,32

 

Not Required

412 shl R8,R6,2

 

Not Required

414 add R9, R8,R7

 

 
416 st R9,f

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Solution:

First of all note the SRC instruction format and its type then according to thiis find the fields in that format. first come opcode of every instruction which is alway of five bits note down it from SRC instruction table then come registers all 5 bits. see it from register table then constants (in case of variables addresser are given simply convert then in to hexadecimal) covert thenm into hexadecimal and any unsued bits as remaning 0s if there are any.

 

e.g for instruction “st R9, f”. it is type C instruction of the following format

 

opcode                        ra(R9)              rb(R0)              c2(f)

00011                          01001              00000              00000 0001 0011 0010

 

total instruction becomes 00011 01001 00000 00000 0001 0011 0010

converting in hexadecimal we obtain 1A400132h the ‘h’ at the end is showing it is hexadecimal number is 8 digit number showing no of total bits are 32 bits.

 

Memory Contents                Hexadecimal Memory Contents

ld R1,g                               0840012Eh

sub R3,R1,R2                     70C22000h

shl R7,R3,4                        E1C60004h

add R9, R8,R7                    62507000h

st R9,f                               1A400132h

 

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