(→Postfix Code) |
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| Line 2: | Line 2: | ||
Consider the following C function: | Consider the following C function: | ||
| − | <c> | + | <source lang="c"> |
int main() { | int main() { | ||
int n = 45, i = 0, j = 1, *seg = &i; | int n = 45, i = 0, j = 1, *seg = &i; | ||
| Line 11: | Line 11: | ||
return 0; | return 0; | ||
} | } | ||
| − | </ | + | </source> |
== Postfix Code == | == Postfix Code == | ||
| Line 17: | Line 17: | ||
The Postfix code for the above function is as follows: | The Postfix code for the above function is as follows: | ||
{{CollapsedCode|Postfix code| | {{CollapsedCode|Postfix code| | ||
| − | <asm> | + | <source lang="asm"> |
TEXT | TEXT | ||
ALIGN | ALIGN | ||
| Line 82: | Line 82: | ||
LEAVE | LEAVE | ||
RET | RET | ||
| − | </ | + | </source> |
}} | }} | ||
[[category:Compiladores]] | [[category:Compiladores]] | ||
[[category:Ensino]] | [[category:Ensino]] | ||
Consider the following C function:
int main() {
int n = 45, i = 0, j = 1, *seg = &i;
while (n-- > 0) {
print(*seg = i + j);
seg = (seg == &i) ? &j : &i;
}
return 0;
}
The Postfix code for the above function is as follows:
| Postfix code |
|---|
TEXT
ALIGN
GLOBAL "main",FUNC
LABEL "main"
ENTER 16 ; n@-4, i@-8, j@-12, seg@-16
;-- initialization:
INT 45
LOCA -4 ; n = 45
INT 0
LOCA -8 ; i = 0
INT 1
LOCA -12 ; j = 1
LOCAL -8 ; &i
LOCA -16 ; seg = &i
;-- while cycle:
ALIGN
LABEL "while"
LOCV -4 ; n
DUP32 ; n (because of n--)
INT 1
SUB ; n-1
LOCA -4 ; n = n-1
INT 0
GT ; n > 0 (n before decrement)
JZ "endwhile"
LOCV -8 ; i
LOCV -12 ; j
ADD ; i+j
DUP32 ; same value (for assignment)
LOCV -16 ; seg
STINT ; *seg = i+j
CALL "print" ; we assume that "print" does not return any value
TRASH 4 ; trash argument (int)
;-- compute trenary operator's value
LOCV -16 ; seg
LOCAL -8 ; &i
EQ ; seg == &i
JZ "false3" ; jump to "false" expression of trenary operator
LOCAL -12 ; &j
JMP "end3" ; jump to end of trenary operator
ALIGN
LABEL "false3"
LOCAL -8 ; &i
ALIGN
LABEL "end3"
DUP32 ; trenary operator's value (duplicated because of assignment)
LOCA -16 ; seg = (seg == &i) ? &j : &i
TRASH 4 ; trash assignment's value, since we used it as an instruction
JMP "while" ; restart while cycle
ALIGN
LABEL "endwhile"
;-- rest of function
INT 0
STFVAL32 ; return value is 0
LEAVE
RET
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