I am trying to write a function to copy words from source memory to destination memory.
I have written the function but I am having difficulty executing the code.
It is giving me execption 4 as an error
.data
.text
main:
.setnoreorder
top: beq $a2,0,done
lw $t1,($a0)
sw $t1,($a1)
add $a0,$a0,4
add $a1,$a1,4
j top
sub $a2,$a2,1
done:
jr $ra #return to the main program
add $0, $0, $0 #nop
I want to write a main program which calls this function to copy 800 words from address 0x50000 to 0x90000 in memory. But when I add the values in $a0-$a2 and run the code it doesnt work. Does anyone know how to fix it. (I am converting C code to MIPS which is why I have included a C tag
Cheers
.text # code starts here
main: # required label
la $a0,dest # point to destination
la $a1,srce # point to source
li $a2,1000 # move this many words
jal block_copy # call the routine
nop
li $v0,10
syscall
###############################################################################
# block copy - moves $a3 words from $a1 to $a0
#
# register usage:
# $a0 address of destination
# $a1 address of source
# $a2 block size (number of words to move)
# $v0 return code (0 means no troubles)
#
block_copy:
move $v0,$a2 # counter/rc
bc_loop:
lw $t0,0($a1) # no DMA here
sw $t0,0($a0) # we have to move a word at a time
addiu $a0,$a0,4 # point to next word in destination
addiu $a1,$a1,4 # point to next word in source
addiu $v0,$v0,-1 # decrement counter
bgtz $v0,bc_loop # keep on moving if counter is positive
jr $ra # return to caller
###############################################################################
.data
dest:
.word 9:1000 # destination 1000 words (all zeroes)
srce:
.word 0:1000 # source 1000 words (all nines)