From: csantill AT lausd DOT k12 DOT ca DOT us
Message-ID: <33D29BAD.43F3@lausd.k12.ca.us>
Date: Sun, 20 Jul 1997 16:13:49 -0700
MIME-Version: 1.0
To: djgpp AT delorie DOT com
Subject: Is the FAQ wrong about FAR/NEAR ptr speed
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from: csantill AT lausd DOT k12 DOT ca DOT us

Thanks to Sinan I'm finally using working FAR PTR mode 13h hack stuff
& I accidentally got the NEAR PTR hack stuff working on my own.  I
decided to test the speed difference & I found there was none!
Everybody on the net(including the mailing list) thinks the NEAR PTR
stuff is faster but on my system it is the exact _SAME_ as the
FAR PTR stuff(about 90 FPS which is great; leaves alot clocks for
animation & game AI).  But I want to find if it is just my system. I've
included my code to see if there is any difference.  Ive got a
Pent 120, 16MB RAM/1MB video(Trident) & I would like to test it on a
true 386 as well as 486.  My code is litely commented & not too hard
to follow.  It basically just fills the screen w/all 256 color 30x's
(people who have taken basic stats know this is the # of trials to
get a decent average).  Well, here's my source.

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#include <sys/farptr.h>
#include <sys/nearptr.h>
#include <dpmi.h>
#include <go32.h>

#include <time.h>

#include <stdlib.h>

#include <string.h>
#include <stdio.h>
// The includes are from my original file - circle/box/line snipped out
// I owe a big thanx to Sinan for my receipt of some actually working VGA
//   code. THAAAAAAAAAAAAAAAANNNNNNNNXXXXXXXXXXXXXXXXXXX!!!!!!!!!!!!! :]

enum GR_MODE{GR_INVALID=-1, GR_TEXT=0x03, GR_VGA=0x13};

enum GR_MODE Set_GR_Mode(enum GR_MODE mode)
{
  __dpmi_regs r;

  memset(&r, 0, sizeof(r));
  r.x.ax=mode;

  return(__dpmi_int(0x10,&r) ? GR_INVALID:mode);
}
// ************************************************************************
void Put_Pix_Far(int x, int y, char c)
{
  _farpokeb(_dos_ds, 0xA0000+(y<<8)+(y<<6)+x,c);
  return;
}
// ************************************************************************
void Put_Pix_Near(int x, int y, char c)
{
  char *v_m=(char *)(0xA0000+__djgpp_conventional_base);
  v_m[(y<<8)+(y<<6)+x] = c;
}
// ************************************************************************
int main(void)
{
  int x, y, co;
  uclock_t st1, st2, et1, et2;

  if(GR_INVALID==Set_GR_Mode(GR_VGA))
  {
    printf("Error setting mode 13h\n");
    exit(8);
  }

// Beginning of FAR PTR SPEED TEST
  st1=uclock();
  for(co=0; co<7680; co++)
    for(y=0; y<200; y++)
      for(x=0; x<320; x++)
        Put_Pix_Far(x,y,co % 256);
  et1=uclock();
// Ending of FAR PTR SPEED TEST

  printf("Done w/FAR PTR test\nHit ENTER to start NEAR PTR TEST\n");
  getchar();

// Beginning of NEAR PTR SPEED TEST
  if(__djgpp_nearptr_enable())
    {
      st2=uclock();
      for(co=0; co<7680; co++)
        for(y=0; y<200; y++)
          for(x=0; x<320; x++)
            Put_Pix_Near(x,y,co % 256);
      et2=uclock();
     };
  __djgpp_nearptr_disable();
// Ending of NEAR PTR SPEED TEST
  Set_GR_Mode(GR_TEXT);

// Show the results
  printf("On my Pentium 120, 16MB RAM, Trident ET6???? w/1MB, while using"
    " RHIDE 1.3, GCC\n2.7 w/-O9 & -m386(-m486 I get the same results), I get"
    " 90.35 fps for both test.\nIs this unusual?\n\nYour results:\n");
// FAR PTR results
  printf("FPS for FAR PTR = %3.2f\n",
    (float)7680/((float)((et1-st1)/UCLOCKS_PER_SEC)));
// NEAR PTR results
  printf("FPS for NEAR PTR = %3.2f\n",
    (float)7680/((float)((et1-st1)/UCLOCKS_PER_SEC)));

  getchar();

  return 0;

}

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