>> for (i=0; i<n-1; i++) {

You dont need to stop i at n-1 since j is stopping at n-i-1. Use:

for (i=0; i<n; i++) {

I'll take a look at the rest in a bit.

Paul

Solved

Posted on 2006-04-07

Hi I have been trying to implent this sorting algorithm for 100 ints.. I used the bubble sort one as well as quicksort...

I have spent nearly two weeks trying to code quicksort and gladly changed to bubble seen that qsort nearly gave me a nervous breakdown!

bubble sort is this:

Bubblesort (int data[],int n) {

int tmp,i,j;

for (i=0; i<n-1; i++) {

for (j=0; j<n-i-1; j++)

if (data[j] > data[j+1]) {

tmp = data[j];

data[j] = data[j+1];

data[j+1] = tmp;

}

}

}

and here is my implementation in bubblesort........

.data

array: .word 0x11,0x111,0x1111111,0x11111,0x1,0x111111111,0x111111,0x111111111,0x111,0x11,0x1111,0x11111111,0x111,0x111111,0x111,0x11111111,0x111111111,0,0x1,0x1111111

.text

dadd r1, r0, r0 ;i

dadd r2, r0, r0 ;j

daddi r6, r2, 8 ;j+1

ld r3, array(r0)

dsll r3, r3, 3 ;n

daddi r7, r3, -8 ;n-1

label: slt r12 ,r1, r7 ;check i< n-1

beqz r12, done ;if not halt

dsub r13, r3, r1 ; else set up for j loop....(ie) n-i

daddi r14, r13, -8 ; n-i-1

here: slt r15, r2, r14 ; if !r2 < n-i-1

beqz r15,inci ; go to next i

ld r19, array(r2) ; else do the swap

ld r20, array(r6)

slt r21, r19, r20

bnez r21, incj

ld r18, array(r6)

ld r16, array(r2)

sd r16, array(r6)

sd r18, array(r2)

incj: daddi r2, r2, 8 ; next iteration of j

daddi r6, r2, 8

j here

inci: dadd r2, r0, r0 ; inc i and reset j and j+ 1

daddi r1, r1, 8

daddi r6, r2, 8

j label ; go again

done: halt

the thing is i have an application from that shows the stats of the reg and mem etc.. a kind of simulator! can be downloaded from here http://www.computing.dcu.ie/~mike/winmips64.html installs in seconds

but this sort is taking way to many clock cycles maybe it can be optimized better also it will not sort the last four of the array...please help

I have spent nearly two weeks trying to code quicksort and gladly changed to bubble seen that qsort nearly gave me a nervous breakdown!

bubble sort is this:

Bubblesort (int data[],int n) {

int tmp,i,j;

for (i=0; i<n-1; i++) {

for (j=0; j<n-i-1; j++)

if (data[j] > data[j+1]) {

tmp = data[j];

data[j] = data[j+1];

data[j+1] = tmp;

}

}

}

and here is my implementation in bubblesort........

.data

array: .word 0x11,0x111,0x1111111,0x111

.text

dadd r1, r0, r0 ;i

dadd r2, r0, r0 ;j

daddi r6, r2, 8 ;j+1

ld r3, array(r0)

dsll r3, r3, 3 ;n

daddi r7, r3, -8 ;n-1

label: slt r12 ,r1, r7 ;check i< n-1

beqz r12, done ;if not halt

dsub r13, r3, r1 ; else set up for j loop....(ie) n-i

daddi r14, r13, -8 ; n-i-1

here: slt r15, r2, r14 ; if !r2 < n-i-1

beqz r15,inci ; go to next i

ld r19, array(r2) ; else do the swap

ld r20, array(r6)

slt r21, r19, r20

bnez r21, incj

ld r18, array(r6)

ld r16, array(r2)

sd r16, array(r6)

sd r18, array(r2)

incj: daddi r2, r2, 8 ; next iteration of j

daddi r6, r2, 8

j here

inci: dadd r2, r0, r0 ; inc i and reset j and j+ 1

daddi r1, r1, 8

daddi r6, r2, 8

j label ; go again

done: halt

the thing is i have an application from that shows the stats of the reg and mem etc.. a kind of simulator! can be downloaded from here http://www.computing.dcu.i

but this sort is taking way to many clock cycles maybe it can be optimized better also it will not sort the last four of the array...please help

5 Comments

>> for (i=0; i<n-1; i++) {

You dont need to stop i at n-1 since j is stopping at n-i-1. Use:

for (i=0; i<n; i++) {

I'll take a look at the rest in a bit.

Paul

I'm not familliar with this language so forgive me if these are not of use.

There's some optimisations you can do:

1. You use -8 and 8 as values. Have you got two more registers you can use to hold them?

2. You load both array elements into registers before comparison. Can you compare a register with a memory location?

3. ld r18, array(r6). Surely, that value is in r20 already.

Are there any instructions to read a number of values into sequential registers in one hit?

Paul

You cannot judge the algorithms efficiency on one set of data. Bubblesort is least efficient if the data is initially in reverse order and most efficient if the data is already sorted. You must test with random data and average the results.

There will also be a minimum number of cycles for any sort, and that is to compare every item with at least one other. How many cycles would that take?

Paul

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