(Created page with "== The Original Code == Consider the following C function: <c> int powmod(int base, int exp, int modulus) { int accum = 1, i = 0, basepow2 = base; while ((exp >> i) > 0) { ...") |
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Consider the following C function: | Consider the following C function: | ||
− | <c> | + | <source lang="c"> |
int powmod(int base, int exp, int modulus) { | int powmod(int base, int exp, int modulus) { | ||
int accum = 1, i = 0, basepow2 = base; | int accum = 1, i = 0, basepow2 = base; | ||
Line 14: | Line 14: | ||
return accum; | return accum; | ||
} | } | ||
− | </ | + | </source> |
== Postfix Code == | == Postfix Code == | ||
The Postfix code for the above function is as follows: | The Postfix code for the above function is as follows: | ||
− | + | {{CollapsedCode|Postfix code| | |
− | <asm> | + | <source lang="asm"> |
TEXT | TEXT | ||
ALIGN | ALIGN | ||
Line 27: | Line 27: | ||
ENTER 12 | ENTER 12 | ||
INT 1 | INT 1 | ||
− | + | LOCAL -4 | |
+ | STINT | ||
INT 0 | INT 0 | ||
− | + | LOCAL -8 | |
− | + | STINT | |
− | + | LOCAL +8 | |
+ | LDINT | ||
+ | LOCAL -12 | ||
+ | STINT | ||
ALIGN | ALIGN | ||
LABEL while | LABEL while | ||
− | + | LOCAL +12 | |
− | + | LDINT | |
+ | LOCAL -8 | ||
+ | LDINT | ||
SHTRU | SHTRU | ||
INT 0 | INT 0 | ||
Line 42: | Line 48: | ||
JZ while_end | JZ while_end | ||
− | + | LOCAL +12 | |
− | + | LDINT | |
+ | LOCAL -8 | ||
+ | LDINT | ||
SHTRU | SHTRU | ||
INT 1 | INT 1 | ||
Line 51: | Line 59: | ||
JZ if_end | JZ if_end | ||
− | + | LOCAL -4 | |
− | + | LDINT | |
+ | LOCAL -12 | ||
+ | LDINT | ||
MUL | MUL | ||
− | + | LOCAL +16 | |
+ | LDINT | ||
MOD | MOD | ||
− | + | DUP32 | |
− | + | LOCAL -4 | |
+ | STINT | ||
TRASH 4 | TRASH 4 | ||
Line 63: | Line 75: | ||
LABEL if_end | LABEL if_end | ||
− | + | LOCAL -12 | |
− | + | LDINT | |
+ | LOCAL -12 | ||
+ | LDINT | ||
MUL | MUL | ||
− | + | LOCAL +16 | |
+ | LDINT | ||
MOD | MOD | ||
− | + | DUP32 | |
− | + | LOCAL -12 | |
+ | STINT | ||
TRASH 4 | TRASH 4 | ||
− | + | LOCAL -8 | |
− | + | LDINT | |
+ | DUP32 | ||
INT 1 | INT 1 | ||
ADD | ADD | ||
− | + | LOCAL -8 | |
+ | STINT | ||
TRASH 4 | TRASH 4 | ||
Line 82: | Line 100: | ||
LABEL while_end | LABEL while_end | ||
− | + | LOCAL -4 | |
− | + | LDINT | |
+ | STFVAL32 | ||
LEAVE | LEAVE | ||
RET | RET | ||
− | </ | + | </source> |
+ | }} | ||
== 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 | |
− | + | yasm -felf powmod.asm | |
− | [[category: | + | [[category:Compiladores]] |
− | [[category: | + | [[category:Ensino]] |
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