Just starting to learn assembly, so I am having trouble with some basic. For example, I am trying to modify a file that normally runs to find the maximum value.
What I am trying to do is iterate through the data_items and modify it by changing the list item, while still maintaining its ability to execute to find the maximum value.
I have tried modifying the start_loop to include an addl data_items, 0x01 but it errors out since it only pulls the first value.
I then adjusted it to do something like addl data_items(,%esi,4), 0x01 and iterate through adjusting it but that didn't work either. I know this is probably very simplistic, but I can't seem to find a method that works.
#
.section .data
data_items: #These are the data items trying to modify and store
.long 3,67,34,222,45,75,54,34,44,33,22,11,66,0
.section .text
.globl _start
_start:
movl $0, %edi
movl data_items(,%edi,4), %eax
movl %eax, %ebx
start_loop:
cmpl $0, %eax
je loop_exit
incl %edi
movl data_items(,%edi,4), %eax
cmpl %ebx, %eax
jle start_loop
movl %eax, %ebx
jmp start_loop
loop_exit:
movl $1, %eax
int $0x80
Once you have an array element in %eax just increment the memory that was last used to read %eax from:
start_loop:
cmpl $0, %eax ; Not actual element if this is 0
je loop_exit
incl data_items(,%edi,4) <<<<<<<<<<<<<<<<<
incl %edi
movl data_items(,%edi,4), %eax
This does not mess with the current finding of the max value. Only next time will the max value be 1 greater.