(→Compiling and Running) |
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== Compiling and Running == | == Compiling and Running == | ||
| − | To compile the Postfix code directly, [[pf2asm]] can be used: | + | To compile the Postfix code directly, [[Compiladores/Projecto de Compiladores/Compiladores Exemplo|pf2asm]] can be used: |
pf2asm powmod.pf | pf2asm powmod.pf | ||
Consider the following C function:
int powmod(int base, int exp, int modulus) {
int accum = 1, i = 0, basepow2 = base;
while ((exp >> i) > 0) {
if (((exp >> i) & 1) == 1)
accum = (accum * basepow2) % modulus;
basepow2 = (basepow2 * basepow2) % modulus;
i++;
}
return accum;
}
The Postfix code for the above function is as follows:
| Postfix code |
|---|
TEXT
ALIGN
GLOBL powmod, FUNC
LABEL powmod
ENTER 12
INT 1
LOCAL -4
STINT
INT 0
LOCAL -8
STINT
LOCAL +8
LDINT
LOCAL -12
STINT
ALIGN
LABEL while
LOCAL +12
LDINT
LOCAL -8
LDINT
SHTRU
INT 0
GT
JZ while_end
LOCAL +12
LDINT
LOCAL -8
LDINT
SHTRU
INT 1
AND
INT 1
EQ
JZ if_end
LOCAL -4
LDINT
LOCAL -12
LDINT
MUL
LOCAL +16
LDINT
MOD
DUP32
LOCAL -4
STINT
TRASH 4
ALIGN
LABEL if_end
LOCAL -12
LDINT
LOCAL -12
LDINT
MUL
LOCAL +16
LDINT
MOD
DUP32
LOCAL -12
STINT
TRASH 4
LOCAL -8
LDINT
DUP32
INT 1
ADD
LOCAL -8
STINT
TRASH 4
JMP while
LABEL while_end
LOCAL -4
LDINT
STFVAL32
LEAVE
RET
|
To compile the Postfix code directly, pf2asm can be used:
pf2asm powmod.pf yasm -felf powmod.asm