Power-Programmierung/CD1.mdf/magazine/drdobbs/1990/08/ladd.lst

File List | 1990-07-10 | 8KB | 441 lines

_OPTIMIZING WITH MICROSOFT C 6.0_
by Scott Robert Ladd

[LISTING ONE]

***********************
*** Microsoft C 6.0 ***
***********************

#include "stdio.h"

/* prototypes */

void doit(int i);

void (* func_ptr)(int i) = doit;

void doit(int i)
    {
    --> push bp
    --> mov  bp,sp
    --> push di
    --> push si
    --> mov  di,WORD PTR [bp+4]

    int loop;

    for (; i > 0; --i)

    --> or  di,di
    --> jle $EX225

        {
        for (loop = 0; loop < 26; ++loop)

        --> $F227:
        --> sub si,si
        --> mov WORD PTR [bp+4],di

            {
            printf("loop character = %c\n", 0x41 + loop);

            --> $F230:
            --> lea  ax,WORD PTR [si+65]
            --> push ax
            --> mov  ax,OFFSET DGROUP:$SG233
            --> push ax
            --> call _printf
            --> add  sp,4
            --> inc  si
            --> cmp  si,26
            --> jl   $F230
            }

        printf("i / 16 = %d\n\n",i / 16);

        --> mov  ax,di
        --> cwd
        --> xor  ax,dx
        --> sub  ax,dx
        --> mov  cx,4
        --> sar  ax,cl
        --> xor  ax,dx
        --> sub  ax,dx
        --> push ax
        --> mov  ax,OFFSET DGROUP:$SG234
        --> push ax
        --> call _printf
        --> add  sp,4
        --> dec  di
        --> jne  $F227

        }

    --> $EX225:
    --> pop si
    --> pop di
    --> mov sp,bp
    --> pop bp
    --> ret
    --> nop
    }

int main(void)
    {
    func_ptr(100);

    --> mov  ax,100
    --> push ax
    --> call WORD PTR _func_ptr
    --> add  sp,2

    return 0;

    --> sub ax,ax
    --> ret
    }



[LISTING TWO]

*****************************************
*** Microsoft C 6.0 (using _fastcall) ***
*****************************************

#include "stdio.h"

/* prototypes */

void doit(int i);

void (* func_ptr)(int i) = doit;

void doit(int i)
    {

    --> push bp
    --> mov  bp,sp
    --> sub  sp,2
    --> push ax
    --> push si

    int loop;

    for (; i > 0; --i)

    --> or  ax,ax
    --> jle $EX225

        {
        for (loop = 0; loop < 26; ++loop)

        --> $F227:
        --> sub si,si

            {
            printf("loop character = %c\n", 0x41 + loop);

            --> $F230:
            --> lea  ax,WORD PTR [si+65]
            --> push ax
            --> mov  ax,OFFSET DGROUP:$SG233
            --> push ax
            --> call _printf
            --> add  sp,4
            --> inc  si
            --> cmp  si,26
            --> jl   $F230

            }

        printf("i / 16 = %d\n\n",i / 16);

        --> mov  ax,WORD PTR [bp-4]
        --> cwd
        --> xor  ax,dx
        --> sub  ax,dx
        --> mov  cx,4
        --> sar  ax,cl
        --> xor  ax,dx
        --> sub  ax,dx
        --> push ax
        --> mov  ax,OFFSET DGROUP:$SG234
        --> push ax
        --> call _printf
        --> add  sp,4
        --> dec  WORD PTR [bp-4]
        --> jne  $F227

        }

        --> $EX225:
        --> pop si
        --> mov sp,bp
        --> pop bp
        --> ret
    }

int main(void)
    {
    func_ptr(100);

    --> mov  ax,100
    --> call WORD PTR _func_ptr

    return 0;

    --> sub ax,ax
    --> ret

    }



[LISTING THREE]

************************
*** Microsoft C 5.10 ***
************************

#include "stdio.h"

/* prototypes */

void doit(int i);

void (* func_ptr)(int i) = doit;

void doit(int i)
    {
    --> push    bp
    --> mov     bp,sp
    --> sub     sp,2
    --> push    di
    --> push    si

    int loop;

    for (; i > 0; --i)

    --> cmp WORD PTR [bp+4],0
    --> jle $FB202
    --> mov di,WORD PTR [bp+4]

        {
        for (loop = 0; loop < 26; ++loop)

        --> $L20002:
        --> sub si,si

            {
            printf("loop character = %c\n", 0x41 + loop);

            --> $L20000:
            --> lea  ax,WORD PTR [si+65]
            --> push ax
            --> mov  ax,OFFSET DGROUP:$SG206
            --> push ax
            --> call _printf
            --> add  sp,4
        }

        --> inc si
        --> cmp si,26
        --> jl  $L20000
        --> mov WORD PTR [bp-2],si  ;loop

        printf("i / 16 = %d\n\n",i / 16);

        --> mov  ax,di
        --> cwd
        --> xor  ax,dx
        --> sub  ax,dx
        --> mov  cx,4
        --> sar  ax,cl
        --> xor  ax,dx
        --> sub  ax,dx
        --> push ax
        --> mov  ax,OFFSET DGROUP:$SG207
        --> push ax
        --> call _printf
        --> add  sp,4

        }

        --> dec di
        --> jne $L20002
        --> mov WORD PTR [bp+4],di

        --> $FB202:
        --> pop si
        --> pop di
        --> mov sp,bp
        --> pop bp
        --> ret
        --> nop

    }

int main(void)
    {
    func_ptr(100);

    --> mov  ax,100
    --> push ax
    --> call WORD PTR _func_ptr
    --> add  sp,2

    return 0;

    --> sub  ax,ax
    --> ret
    }



[LISTING FOUR]

********************
*** Watcom C 7.0 ***
********************

#include "stdio.h"

/* prototypes */

void doit(int i);

void (* func_ptr)(int i) = doit;

void doit(int i)
    {
    int loop;

    --> push    bx
    --> push    cx
    --> push    dx
    --> mov     cx,ax
    --> jmp     short L3

    for (; i > 0; --i)
        {
        for (loop = 0; loop < 26; ++loop)
            {
            --> L1:
            --> mov     bx,0041H

            printf("loop character = %c\n", 0x41 + loop);

            --> L2:
            --> push    bx
            --> mov     ax,offset DGROUP:L4
            --> push    ax
            --> call    near ptr printf_
            --> add     sp,0004H
            --> inc     bx
            --> cmp     bx,005bH
            --> jne     L2

            }

        printf("i / 16 = %d\n\n",i / 16);

        --> mov     bx,0010H
        --> mov     ax,cx
        --> cwd
        --> idiv    bx
        --> push    ax
        --> mov     ax,offset DGROUP:L5
        --> push    ax
        --> call    near ptr printf_
        --> add     sp,0004H
        --> dec     cx

        }

    --> L3:
    --> test    cx,cx
    --> jg      L1

    --> pop     dx
    --> pop     cx
    --> pop     bx
    --> ret

    }

int main(void)
    {

    func_ptr(100);

    --> mov     ax,0064H
    --> call    word ptr _func_ptr

    return 0;

    --> xor     ax,ax
    --> ret

    }


[Listing Five]
/* Skeleton Program demonstrating the use of based pointers */

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <malloc.h>

#define MAX_TAG 2000
unsigned long get_size(void);
_segment segvar;           /* name a segment for use with based pointers */

/* set up structures and tags within segment segvar */

typedef mytag {
char filename[14];
unsigned long size;
mytag _based(segvar) *next;
} _based(segvar) *PTAG, TAG;

main() {

   PTAG head, curptr;

/* Allocate a based heap of MAX_TAG structs. Put segment address in segvar. */

   if((segvar = _bheapseg(sizeof(TAG) * MAX_TAG))) == NULLSEG){
      printf("error allocating based heap \n");
      exit(-1);
   }

/* Allocate memory within segvar for first structure in linked list */

   if((head = _bmalloc(segvar, sizeof(TAG)) == _NULLOFF) {
   printf("error allocating TAG \n");
   exit(-1);
   }
   head->size = get_size();
   _fstrcpy((char far *) head->filename, get_name()); /* get a
   filename and copy it to segvar */

   if((head->next = _bmalloc(segvar, sizeof(TAG)) == _NULLOFF) {
   printf("error allocating TAG \n");
   exit(-1);
   }
.
.
.
}
unsigned long get_size(void) {
return 1;
}

char *get_name(void) {
return("foo");
}