How to merge shapefiles?

Merge sort in MIPS Assembly help?

• I have a program in MIPS assembly that is supposed to run a merge sort on a fixed list of integers. I seem to have hit a bug. My end list isn't correctly sorted and there are some 0s that are messing up the program. I am using a stack and am putting saved values into that stack. My main program creates a stack. [code] main: li $s0, 0 addi $s0, $s0, 0 # $s0=lo addi $s1, $s1, 19 # $s1=hi la $a0, list addi $s2, $s2, 0 addi $sp, $sp, -20 sw $ra, 16($sp) sw $a0, 12($sp) sw $s2, 8($sp) # m sw $s1, 4($sp) # hi sw $s0, 0($sp) # lo jal merge_sort merge_sort: slt $t0, $s0, $s1 # $t0=1 if lo<hi bne $t0, $zero, L1 # if lo<hi branch to L1 jr $ra L1: add $t0, $s0, $s1 # t0 = lo+hi div $s2, $t0, 2 # m=lo+hi/2 addi $sp, $sp, -20 sw $ra, 16($sp) sw $a0, 12($sp) sw $s2, 8($sp) # m sw $s1, 4($sp) # hi sw $s0, 0($sp) # lo add $s1, $s2, $zero # hi=m jal merge_sort # merge_sort(a(a0), ?, $s0, $ L2: addi $sp, $sp, -20 sw $ra, 16($sp) sw $a0, 12($sp) sw $s2, 8($sp) # m sw $s1, 4($sp) # hi sw $s0, 0($sp) # lo addi $s0, $s2, 1 # lo=m+1 jal merge_sort addi $sp, $sp, 20 ##pop stack ###load values for merge and jal to merge## /// I think I might be having a problem here//// lw $s0, 0($sp) lw $s1, 4($sp) lw $s2, 8($sp) lw $a0, 12($sp) jal merge /////Or Problem here/////// ####return from merge load values, pop and return to previous address (L2 most likely)### lw $s0, 0($sp) lw $s1, 4($sp) lw $s2, 8($sp) lw $a0, 12($sp) lw $ra, 16($sp) addi $sp, $sp, 20 jr $ra ######################################... Merge ######################################... merge: li $t2, 0 # i li $t3, 0 # j li $t4, 0 # k move $t2, $s0 # i=lo ##FOR LOOP FROM MERGE### ######################## for: slt $t1, $s1, $t2 # $t1=1;hi<i bne $t1, $zero, next #if i>hi next loop la $a0, list # array list into $a0 move $t5, $t2 # save iterator sll $t5, $t5, 2 # shift by 4 add $t6, $t5, $a0 # $t6=a[i] lw $t1, 0($t6) la $a0, b_array move $t7, $t2 sll $t7, $t7, 2 # shift 4 add $t7, $t7, $a0 sw $t1, 0($t7) # $b[i]=a[i] addi $t2, $t2, 1 j for ###START OF WHILE LOOP 1#### next: move $t2, $s0 # i=lo addi $t3, $s2, 1 # j=m+1 (Hopefully) move $t4, $s0 # k=lo while1: slt $t1, $s2, $t2 #$t1=1;m<i bne $t1, $zero, while2 #ifm<i branch to while2 slt $t1, $s1, $t3 #$t1=1;hi<j bne $t1, $zero, while2 #if j>hi branch to while2 ##### getting b[i] & storing into $s3 ####### move $t5, $t2 #preserve i into $t5 la $a0, b_array sll $t5, $t5, 2 add $t6, $t5, $a0 #load b[i] into $t6 lw $s3, 0

• Answer:

  I see 3 problems: 1.) You're not initializing the arguments registers that you probably need to pass to the merge function. 2.) In your merge function, you're calling lw when you should be calling sw to preserve your registers 3.) In your merge function, you don't have a line for storing your $ra register.