(→Postfix Code) |
(→Compiling and Running) |
||
| (One intermediate revision by the same user not shown) | |||
| Line 3: | Line 3: | ||
Consider the following C function: | Consider the following C function: | ||
| − | <c> | + | <source lang="c"> |
extern int printf(const char *format, ...); | extern int printf(const char *format, ...); | ||
int printlist(int lo, int hi) { | int printlist(int lo, int hi) { | ||
| Line 13: | Line 13: | ||
return ix; | return ix; | ||
} | } | ||
| − | </ | + | </source> |
== Postfix Code == | == Postfix Code == | ||
| Line 19: | Line 19: | ||
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"> |
EXTRN printf | EXTRN printf | ||
| Line 102: | Line 102: | ||
LEAVE ; release stack frame | LEAVE ; release stack frame | ||
RET ; return control to caller | RET ; return control to caller | ||
| − | + | </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 while.pf | |
| − | + | yasm -felf while.asm | |
[[category:Compiladores]] | [[category:Compiladores]] | ||
[[category:Ensino]] | [[category:Ensino]] | ||
Consider the following C function:
extern int printf(const char *format, ...);
int printlist(int lo, int hi) {
int ix = lo;
while (ix < hi) {
printf("%d\n", ix);
ix++;
}
return ix;
}
The Postfix code for the above function is as follows:
| Postfix code |
|---|
EXTRN printf
TEXT
ALIGN
GLOBL printlist, FUNC
LABEL printlist
ENTER 4 ; ix@-4 lo@+8 hi@+12
; int ix = lo is NOT an assignment
LOCAL +8
LDINT ; read lo
LOCAL -4
STINT ; write to ix
ALIGN
LABEL whiletest
LOCAL -4
LDINT ; read ix
LOCAL +12
LDINT ; read hi
LT
JZ whileend
; start while body
; prepare arguments for calling printf
LOCAL -4
LDINT ; second printf arg: read ix
; put string literal in read-only memory
RODATA
ALIGN
LABEL strlit
SSTRING "%d\n"
; now get the address of the string literal (strlit)
TEXT
ADDR strlit ; first printf arg: string literal address
; args are in the stack: call the function
CALL printf
; clean args
TRASH 8
; get printf return value
LDFVAL32
; get rid of return value (printf used as instruction)
TRASH 4
; increment ix
LOCAL -4
LDINT ; read ix
DUP32
INT 1
ADD
LOCAL -4
STINT ; ix = ix + 1
; trash old value of ix
TRASH 4
; end while body
; restart while cycle
JMP whiletest
; this is the while exit point
ALIGN
LABEL whileend
; prepare return value
LOCAL -4
LDINT ; read ix
; put it in the accumulator (register) to conform with Cdecl
STFVAL32
LEAVE ; release stack frame
RET ; return control to caller
|
To compile the Postfix code directly, pf2asm can be used:
pf2asm while.pf yasm -felf while.asm