Using the Bubble Sort program from lecture notes 7, change the following two sec
ID: 3926319 • Letter: U
Question
Using the Bubble Sort program from lecture notes 7, change the following two sections to subroutines.
1. Deallocate local variables
2. Swap positions.
Bubble sort
arr equ 13 ; distance of the variable arr from stack top
arcnt equ 12 ; distance of the variable arcnt from stack top
buf equ 3 ; distance of local variable buf from stack top
in_order equ 2 ; distance of local variable in_order from stack top
inner equ 1 ; distance of local variable inner from stack top. 1 =in ;order, 0 = not
iteration equ 0 ; distance of local variable iteration from stack top
true equ 1
false equ 0
n equ 30 ; array count (number of elements in the array)
local equ 4 ; number of bytes used by local variables
org $1000
array_x db 3,29,10,98,54,9,100,104,200,92,87,48,27,22,71
db 1,62,67,83,89,101,190,187,167,134,121,20,31,34,54
org $1500
lds #$1500 ; initialize stack pointer
ldx #array_x ;pass array start address in stack
pshx
ldaa #n ;pass number of elements in stack
psha
jsr bubble
leas 3,sp ; deallocate space used by outgoing parameters
Swi ; break to D-Bug12 monitor
;---------------------Bubble Sort Subroutine--------------------------------;
Setup subroutine part of stack.
bubble pshd ; save registers (note did not save A reg)
pshy
pshx
leas -local,sp ; allocate space for local variables
ldaa arcnt,sp ; get the number of iterations to be performed
deca ; "
staa iteration,sp ; “
;Main loop. N-1 times or until no swaps
ploop ldaa #true ; set array in_order flag to true before any iteration
staa in_order,sp ; "
ldx arr,sp ; use index register X as the array pointer
ldaa iteration,sp ; initialize inner loop count for each iteration
staa inner,sp ; “
;Walk across and compare/switch loop
cloop ldaa 0,x ; compare two adjacent elements
cmpa 1,x ; "
bls looptest
; the following five instructions swap the two adjacent elements
staa buf,sp ; swap two adjacent elements
ldaa 1,x ; "
staa 0,x ; "
ldaa buf,sp ; "
staa 1,x ; "
ldaa #false ; reset the in-order flag. To zero
staa in_order,sp ; "
;check if finished
looptest inx
dec inner,sp
bne cloop
tst in_order,sp ; test if in order
bne done
dec iteration,sp ; finished all iterations?
bne ploop
; deallocate local variables
done leas local,sp
pulx
puly
puld
rts
end
Here is a link where you can see the bubble sort program
Explanation / Answer
A bubble sort test harness to use the subroutine
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