Programming Forums - x86 assembly (segfault)

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x86 assembly (segfault)

Consider this bit of code which is part of a kinda itoa procedure, only the string is reversed:

#get a number from a parameter, this bit is identical to functional bits getting chars and strings

movl (%esi), %eax

addl $4, %esi



#uses the %ecx-register for the string, adds a zero at the beginning for later reversal purposes

movl $0, %ecx

incl %ecx



#the actual procedure

loop:

cmpl $0, (%eax)

je done

cdq #is this really necessary? doesn't seem to make any difference atm

movl $10, %ebx # the divisor

idivl %ebx

addl $48, %edx

movb (%edx), %bl

movb %bl, (%ecx)

incl %ecx

jmp loop

ignoring the fact that it doesn't handle negative integers at the moment, I can't for the life of me see why this would be segfaulting...

I've found that (at least the first) reason for the segfault is this line:

movl (%esi), %ecx

The %esi register contains the parameters for the whole program, and this line is identical to functioning procedures for getting both chars and strings, so I gather there must be some other method of handling ints?