Cirrus Logic CS485 Manual do Utilizador descarregar pdf (Página 25)

CS485G Spring 2015 25

2. Example

1 int add3(int x) {

2 int localx = x;

3 incrk(&localx, 3);

4 return localx;

5 }

6 void incrk(int

ip, int k) {

ip += k;

8 }

add3:

pushl %ebp # save old ebp

movl %esp, %ebp # new ebp

subl $24, %esp # allocate 24 bytes (6 "chunks")

movl 8(%ebp), %eax # a = x

movl %eax, -4(%ebp) # localx = x

movl $3, 4(%esp) # actual2 = 3

leal -4(%ebp), %eax # a = &localx

movl %eax, (%esp) # actual1 = &localx

call incrk # a = incrk(actual1, actual2)

movl -4(%ebp), %eax # a = localx

addl $24, %esp # deallocate 24 bytes

popl %ebp # restore ebp

ret # return

3. right before the call to incrk(), the stack has these “chunks”:

x at 8(%ebp)

return address to add3’s caller

old ebp at (%ebp)

localx at -4(%ebp)

unused

actual 2 at 4(esp)

actual 1 at (esp)

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Cirrus Logic CS485 Manual do Utilizador Página 25