1. We have the following set-up: • 256 byte main memory • words are aligned (tha
ID: 3812873 • Letter: 1
Question
1. We have the following set-up:
• 256 byte main memory
• words are aligned (that is, they have an address divisible by 4)
• addresses are 8 bits
• 64 byte cache that uses direct-mapping
• each line of cache is 8 bytes
• first word in a line has an address divisible by 8
Show what happens in the cache by creating a table with the headings
address, tag, line inde,x valid, hit/miss, range of addresses to copy
for the memory addresses
12, 13, 14, 31, 32, 122, 78, 12
The address, line index, and address range values should be in base-10; the tag should be in binary.
In the last column of the table, the possible values should be
(a) if the appropriate line of the cache has not been given values, then give the range of memory addresses to copy to cache, e.g., 12-15
(b) use current values in cache
(c) if the appropriate line of the cache is being used, then give the range of memory addresses to copy to cache and indicate it is a replacement, e.g., 4-7 (replace)
For example, I get the following for the first line:
address tag line index valid hit/miss range of addresses to copy
12 00 1 N, set miss 8-15
Explanation / Answer
.data
# const string for welcome
welc: .asciiz "Welcome to SPIM Calculator one.0! "
p_int: .asciiz " Please provide associate integer: "
p_op: .asciiz " Please provide associate operator: "
i_err: .asciiz " Input Incorrect, unhealthy operator! "
again_str: .asciiz "Another calculation? (y/n)"
rmndr: .asciiz " r: "
new_line: .asciiz " "
int1: .word one # house to carry int one
int2: .word one # house to carry int two
raw_in: .space one # house to carry raw input
op: .space one # house to carry operator char
a_char: .space one # house to carry once more char
out: .word one # house to carry output
remain: .word one # house to carry remainder
#operator constants
c_plus: .ascii "+" # const for +
c_min: .asciiz "-" # const for -
c_mult: .asciiz "*" # const for *
c_divi: .asciiz "/" # const for /
c_eq: .asciiz "=" # const for =
c_no: .asciiz "n" # const for n
.text
.globl main
main: li $v0, four # syscall four, print string
la $a0, welc # provide argument: string
syscall # really print string
calc: la $t6, stay # load remainder variable
move $t6, $zero # store zero in remainder (reset)
li $v0, four # syscall four, print string
la $a0, purpose # provide argument: string
syscall # really print string
li $v0, five # tell syscall we would like to scan int one
syscall # really scan in int one
la $s1, int1 # load int1 into $s1
move $s1, $v0 # copy the number from $v0 to int1
li $v0, four # syscall four, print string
la $a0, purpose # provide argument: string
syscall # really print string
li $v0, five # tell syscall we would like to scan int two
syscall # really scan in int two
la $s2, int2 # provide $s2 the address to carry int two
move $s2, $v0 # copy the number from $v0 to $s2
li $v0, four # syscall four, print string
la $a0, p_op # provide argument: string
syscall # really print string
li $v0, eight # tell syscall we would like to scan operator
la $a0, op # provide $a0 the address to carry the operator
syscall # really scan in operator
lb $t0, op # load the primary computer memory unit of op
li $t1, '+' # load const for and
li $t2, '-' # load const for minus
li $t3, '*' # load const for multiplying
li $t4, '/' # load const for dividing
la $s0, out # load intent on $s0
beq $t0, $t1, and # we're adding
beq $t0, $t2, minus # we're subtracting
beq $t0, $t3, multi # we're multiplying
beq $t0, $t4, divi # we're dividing
# else
j error # incorrect input
plus: add $s0, $s1, $s2 # add our ints, store in $t0
j print
minus: sub $s0, $s1, $s2 # cypher our ints, store in $t0
j print
multi: slt $t1, $t2, $s2 # if our counter is a smaller amount than int2, set $t1 to one
beq $t1, $zero, print # if we've reached int2, we're done
add $s0, $s1, $s1 # add int1 and int1, store in out
j multi # loop
divi: la $t0 stay # load remainder into $t0
move $t0, $s1 # set remainder to dividend
add $s0, $zero, $zero # embarked on to zero, simply just in case
loop: slt $t1, $t0, $s2 # if remainder is a smaller amount than divisor, set 1
beq $t1, $zero, print # if we're done branch to done
sub $t0, $t0, $s2 # sub divisor from remainder, store in remainder
addi $s0, $s0, one # increment quotient by one
j loop # loop
print: li $v0, one # tell syscall we would like to print int
la $a0, int1 # provide syscall int1 to print
syscall # really print int
li $v0, four # tell syscall we would like to print string
lb $a0, op # tell syscall we would like to print operator
syscall # really print string
li $v0, one # tell syscall we would like to print int
la $a0, int2 # provide syscall int2 to print
syscall # really print int
li $v0, four # tell syscall we would like to print string
la $a0, c_eq # tell syscall we would like to print operator
syscall # really print string
li $v0, one # tell syscall we would like to print number
la $a0, out # provide syscall our output
syscall # really print int
la $t0, stay # load remainder
beq $t0, $zero, once more # if we've no remainder, end printing
li $v0, four # tell syscall we would like to print string
la $a0, rmndr # tell syscall we would like to print remainder string
syscall # print "r: "
li $v0, one # tell syscall we would like to print int
la $a0, stay # provide syscall our remainder to print
syscall # print remainder
again: li $v0, four # tell syscall we would like to print string
la $a0, printing operation # tell syscall to print printing operation
syscall
la $a0, once more_str # load prompt for again string for syscall
syscall
li $v0, eight # tell syscall we would like to scan string
la $a0, a_char # tell syscall to place it in $a0
syscall
lb $t0, a_char
li $t1, 'n' # get n char thus we will compare
beq $t0, $t1, exit # if we tend to ar done, exit
#else loop
j calc # jump to starting
error: li $v0, four # tell syscall we would like to print string
la $a0, i_err # provide syscall what to print
syscall # really print
j once more # move to prompt for try
exit: li $v0, ten # exit code
syscall #exit!
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