Assembly Homework
Posted: Thu Oct 23, 2008 10:30 pm
I just put off my CPE321 homework of over a week until the last minute--yet again. I've been scrambling to get it done in the last few hours. Here's the two homework assignments so far. If you're wondering, it's SRC assembly, which pretty much doesn't exist. You aren't going to find the processor, and we're only simulating it in Java applets, rofl.
Funky ass character counter:
strcat()
This was a particular bitch, because we had to write our own printing subroutine to print the two sources and the concatenated string.
Funky ass character counter:
Code: Select all
;Falco Girgis
;CPE321 Homework
;Given a string:
;number of uppercase letters in r4
;number of lowercase letters in r5
;number of non-alpha on the stack (and r6 at the end)
.org 0
main:
la r30, stack
la r0, string
lar r18, charcount
brl r31, r18 ;run our charcount subroutine
;Pop value from stack and store in r6
ld r6, (r30)
addi r30, r30, -4
stop
charcount:
;initialize labels
lar r28, loop
lar r27, capcheck
lar r26, nonalpha
lar r25, loopend
la r21, a
ld r21, 0(r21)
la r22, z
ld r22, 0(r22)
la r24, A
ld r24, 0(r24)
la r19, Z
ld r19, 0(r19)
;Clear our counters
sub r4, r4, r4 ;Upper case characters
sub r5, r5, r5 ;lower case characters
addi r30, r30, 4 ;adjust stack pointer for push
st r4, (r30) ;Push a 0 onto stack.
addi r18, r0, 0 ;copy string to r18
loop:
ld r20, 0(r18) ;load character
brzr r31, r20 ;break to "out" if character is null
sub r23, r20, r21 ;char - a
brmi r27, r23 ;go to "capcheck" if r23 is negative
sub r23, r22, r20 ;z - char
brmi r26, r23 ;go to "nonalpha" if r23 is negative
addi r5, r5, 1
loopend:
addi r18, r18, 4 ;increase string pointer
br r28 ;return to beginning of the loop
capcheck:
sub r23, r20, r24 ;char - 'A'
brmi r26, r23
sub r23, r19, r20 ;'Z' - char
brmi r26, r23
addi r4, r4, 1 ;add to cap count
br r25
nonalpha:
;pop current number of nonalphas
ld r23, (r30)
addi r30, r30, -4
;add one to counter
addi r23, r23, 1
;push number back.
addi r30, r30, 4 ;adjust stack pointer for push
st r23, (r30) ;assume non-alpha count was in r23. Push it
br r25
.org 500
a: .dc "a"
z: .dc "z"
A: .dc "A"
Z: .dc "Z"
string: .dc "ABCDEFGHabIJKLMN98OPQRSTUVWZYZabcdefghijkAAlmnopqrs98tuvwxyz!?*&*$01ad234BH56789",0
.org 1000
stack:
This was a particular bitch, because we had to write our own printing subroutine to print the two sources and the concatenated string.
Code: Select all
; Falco Girgis
; CPE321 SRC Homework 2
; Strcat subroutine
;r4 returns length of concatenated string.
COSTAT: .equ -3824
COUT: .equ -3820
.org 0
main: lar r0, string1
lar r1, string2
lar r2, string3
lar r13, newline
lar r30, stack
lar r3, endL
st r13, (r30) ;Add newline to stack
addi r30, r30, 4
st r1, (r30) ;Add second string to stack
addi r30, r30, 4
st r13, (r30) ;Add newline to stack
addi r30, r30, 4
st r0, (r30) ;Add first string to stack
addi r30, r30, 4
la r18, print ;Print first string
brl r31, r18
la r18, print ;Print newline
brl r31, r18
la r18, print ;Print second string
brl r31, r18
la r18, print ;Print newline
brl r31, r18
st r3, (r30) ;Put end on the stack
addi r30, r30, 4 ;Increment stack pointer
lar r18, concat
brl r31, r18 ;Branch to concat
endL:
st r13, (r30) ;Add newline to stack
addi r30, r30, 4
st r2, (r30) ;Add dest string to stack
addi r30, r30, 4
la r18, print ;Print dest string
brl r31, r18
la r18, print ;Print newline
brl r31, r18
stop
concat: lar r22, loop1
lar r23, loop1end
lar r26, loop2
lar r27, loop2end
addi r25, r2, 0 ;r25 points to dest
st r0, (r30) ;Push first string onto stack
addi r30, r30, 4
la r18, strlen ;Call strlen
brl r31, r18
addi r18, r0, 0 ;copy string1's location to r18
sub r20, r20, r20 ;set iterator to 0
loop1: sub r21, r4, r20 ;find difference between strlen and iterator
brzr r23, r21
ld r19, 0(r18) ;load char from 1st string
st r19, 0(r25) ;store char in new string
addi r25, r25, 4 ;increase dest pointer
addi r18, r18, 4 ;increase source pointer
addi r20, r20, 1 ;increase iterator
br r22
loop1end:
st r1, (r30) ;Push second string onto stack
addi r30, r30, 4
la r18, strlen ;Call strlen
brl r31, r18
addi r18, r1, 0 ;copy string2's location to r18
sub r20, r20, r20 ;set iterator to 0
loop2: sub r21, r4, r20 ;find difference between strlen and iterator
brzr r27, r21
ld r19, 0(r18) ;load char from 2nd string
st r19, 0(r25) ;store char in new string
addi r25, r25, 4 ;increase dest pointer
addi r18, r18, 4 ;increase source pointer
addi r20, r20, 1 ;increase iterator
br r26
loop2end: st r2, (r30) ;Push destination string onto stack
addi r30, r30, 4
la r18, strlen ;Call strlen
brl r31, r18
st r25, 0 ;append a null character to the end.
addi r30, r30, -4 ;decrement stack pointer
ld r31, (r30) ;load original return address
br r31 ;return to main
;==============String Length==========
strlen: lar r29, Out
lar r28, Loop
addi r30, r30, -4 ;Decrement stack pointer
ld r17, 0(r30) ;Pop
addi r18, r17, 0 ;Copying r17 to r18
sub r19, r19, r19 ;counter = 0
Loop: ld r20, 0(r18) ;load a character
brzr r29, r20 ;if(char==0) goto OUT
addi r19, r19, 1 ;add to counter
addi r18, r18, 4 ;increase character pointer
br r28 ;do another loop iteration
Out: addi r4, r19, 0 ;store result in r4
br r31 ;return
; ===============Print================
print: lar r5, Wait
lar r6, End2
lar r7, Loop3
addi r30, r30, -4
ld r8, (r30)
addi r9, r8, 0
Loop3: ld r10, 0(r9)
brzr r6, r10
Wait: ld r11, COSTAT
brpl r5, r11
st r10, COUT
addi r9, r9, 4
br r7
End2: br r31
;===================================
.org 1500
newline: .dc 0x0a, 0x0d, 0
string1: .dc "Carry on my wayward son. ", 0
string2: .dc "There will be peace when you are done.", 0
string3: .dc "", 0
.org 3000
stack: 
Good luck, man.