|
|
| (2 intermediate revisions by the same user not shown) |
| Line 1: |
Line 1: |
| == The Original Code ==
| | #REDIRECT [[ist:Code Generation/Example 3]] |
| | |
| Consider the following C function:
| |
| | |
| <c>
| |
| int *click(int *x, int dim) {
| |
| int *res, i;
| |
| for (i = dim-2, res = x+dim-1; i >= 0; i--)
| |
| if (x[i] > *res) res = &x[i];
| |
| return res;
| |
| }
| |
| </c>
| |
| | |
| == Postfix Code ==
| |
| | |
| The Postfix code for the above function is as follows:
| |
| | |
| <asm>
| |
| TEXT
| |
| ALIGN
| |
| GLOBL click, FUNC
| |
| LABEL click
| |
| ENTER 8 ;-- x@+8 dim@+12 res@-4 i@-8
| |
| | |
| ;; for init
| |
| | |
| ;; i = dim-2
| |
| LOCV 12
| |
| INT 2
| |
| SUB
| |
| DUP
| |
| LOCA -8
| |
| TRASH 4
| |
| | |
| ;; res = x + dim - 1
| |
| LOCV 8
| |
| LOCV 12
| |
| INT 4
| |
| MUL
| |
| ADD
| |
| INT 1
| |
| INT 4
| |
| MUL
| |
| SUB
| |
| DUP
| |
| LOCA -4
| |
| TRASH 4
| |
| | |
| ;; for test
| |
| ALIGN
| |
| LABEL for
| |
| LOCV -8
| |
| INT 0
| |
| GE
| |
| JZ forend
| |
| | |
| ;; for block
| |
| | |
| ;; if test
| |
| LOCV 8 ; x
| |
| LOCV -8 ; i
| |
| INT 4
| |
| MUL
| |
| ADD ; x+i
| |
| LOAD ; x[i] = *(x+i)
| |
| | |
| LOCV -4 ; res
| |
| LOAD ; *res
| |
| | |
| GT
| |
| JZ ifend
| |
| | |
| ;; if block
| |
| LOCV 8 ; x
| |
| LOCV -8 ; i
| |
| INT 4
| |
| MUL
| |
| ADD ; x+i = &x[i]
| |
| DUP
| |
| LOCA -4 ; res = &x[i]
| |
| TRASH 4
| |
| | |
| ALIGN
| |
| LABEL ifend
| |
| | |
| ;; for increment
| |
| ALIGN
| |
| LABEL forincr
| |
| LOCV -8 ; i
| |
| DUP
| |
| INT 1
| |
| SUB
| |
| LOCA -8
| |
| TRASH 4
| |
| | |
| ;; for jump to cycle
| |
| JMP for
| |
| | |
| ALIGN
| |
| LABEL forend
| |
| | |
| ;; return
| |
| LOCV -4 ; res
| |
| | |
| POP
| |
| LEAVE
| |
| RET
| |
| </asm>
| |
| | |
| == Compiling and Running ==
| |
| | |
| To compile the Postfix code directly, [[pf2asm]] can be used:
| |
| | |
| * pf2asm click.pf
| |
| * yasm -felf click.asm
| |
| | |
| [[category:Compiladores]]
| |
| [[category:Ensino]]
| |