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The following pure-Postfix program illustrates duplication of double-precision floating point numbers on the stack. | The following pure-Postfix program illustrates duplication of double-precision floating point numbers on the stack. | ||
The C equivalent would be (roughly): | The C equivalent would be (roughly): | ||
| − | <c> | + | <source lang="c"> |
int main() { | int main() { | ||
extern void printd(double); | extern void printd(double); | ||
| Line 13: | Line 11: | ||
return 0; | return 0; | ||
} | } | ||
| − | </ | + | </source> |
Note that this program's code does not necessarily correspond to any particular code generator output. | Note that this program's code does not necessarily correspond to any particular code generator output. | ||
| − | + | {{CollapsedCode|Postfix code| | |
| − | <asm> | + | <source lang="asm"> |
;;-- generation of the "_main" function | ;;-- generation of the "_main" function | ||
TEXT | TEXT | ||
ALIGN | ALIGN | ||
| − | + | GLOBAL _main, FUNC | |
LABEL _main | LABEL _main | ||
ENTER 16 ; d@-8 and e@-16 | ENTER 16 ; d@-8 and e@-16 | ||
| Line 29: | Line 27: | ||
ALIGN | ALIGN | ||
LABEL _L123 | LABEL _L123 | ||
| − | + | SDOUBLE 3.3e-2 | |
;;-- load literal onto stack | ;;-- load literal onto stack | ||
TEXT | TEXT | ||
ADDR _L123 | ADDR _L123 | ||
| − | + | LDDOUBLE | |
;;-- to perform the first assignment (to "e"), duplicate the value on the stack | ;;-- to perform the first assignment (to "e"), duplicate the value on the stack | ||
| − | + | DUP64 | |
LOCAL -16 ; write value to "e" | LOCAL -16 ; write value to "e" | ||
| − | + | STDOUBLE | |
;;-- to perform the second assignment (to "d"), duplicate the value on the stack | ;;-- to perform the second assignment (to "d"), duplicate the value on the stack | ||
| − | + | DUP64 | |
LOCAL -8 ; write value to "d" | LOCAL -8 ; write value to "d" | ||
| − | + | STDOUBLE | |
;;-- the assignments are an instruction: trash the value left on the stack | ;;-- the assignments are an instruction: trash the value left on the stack | ||
| Line 53: | Line 51: | ||
;;-- now to perform the add operation | ;;-- now to perform the add operation | ||
LOCAL -8 | LOCAL -8 | ||
| − | + | LDDOUBLE ; load "d" | |
LOCAL -16 | LOCAL -16 | ||
| − | + | LDDOUBLE ; load "e" | |
DADD ; leaves result on the stack | DADD ; leaves result on the stack | ||
| Line 65: | Line 63: | ||
INT 0 | INT 0 | ||
| − | + | STFVAL32 | |
LEAVE | LEAVE | ||
RET | RET | ||
| − | </ | + | </source> |
| − | + | }} | |
== Compiling and Running == | == Compiling and Running == | ||
| − | Assuming that the code above is in file dbl.pf, the following commands would compile and run the program: | + | Assuming that the code above is in file dbl.pf, the following commands ([[Compiladores/Projecto de Compiladores/Compiladores Exemplo|pf2asm]]) would compile and run the program: |
| − | + | pf2asm dbl.pf | |
| − | + | yasm -felf32 dbl.asm | |
| − | + | ld -m elf_i386 -o dbl dbl.o -lrts | |
| − | + | ./dbl | |
| − | [[category: | + | [[category:Compiladores]] |
| − | [[category: | + | [[category:Ensino]] |
The following pure-Postfix program illustrates duplication of double-precision floating point numbers on the stack.
The C equivalent would be (roughly):
int main() {
extern void printd(double);
double d, e;
d = e = 3.3e-2;
printd(d + e);
return 0;
}
Note that this program's code does not necessarily correspond to any particular code generator output.
| Postfix code |
|---|
;;-- generation of the "_main" function
TEXT
ALIGN
GLOBAL _main, FUNC
LABEL _main
ENTER 16 ; d@-8 and e@-16
;;-- put double literal in RODATA
RODATA
ALIGN
LABEL _L123
SDOUBLE 3.3e-2
;;-- load literal onto stack
TEXT
ADDR _L123
LDDOUBLE
;;-- to perform the first assignment (to "e"), duplicate the value on the stack
DUP64
LOCAL -16 ; write value to "e"
STDOUBLE
;;-- to perform the second assignment (to "d"), duplicate the value on the stack
DUP64
LOCAL -8 ; write value to "d"
STDOUBLE
;;-- the assignments are an instruction: trash the value left on the stack
TRASH 8
;;-- now to perform the add operation
LOCAL -8
LDDOUBLE ; load "d"
LOCAL -16
LDDOUBLE ; load "e"
DADD ; leaves result on the stack
EXTERN printd
CALL printd
TRASH 8 ; argument value no longer needed
INT 0
STFVAL32
LEAVE
RET
|
Assuming that the code above is in file dbl.pf, the following commands (pf2asm) would compile and run the program:
pf2asm dbl.pf yasm -felf32 dbl.asm ld -m elf_i386 -o dbl dbl.o -lrts ./dbl