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c++.windows.16-bits - Comparing Huge Pointers

reply Mark Evans <mevans zyvex.com> writes:
There is an include file called HUGEPTR.H which for some reason is not in the
win16 subfolder.  (Contents appended below.)

I just want to ask whether this is the "approved" method of comparing and
differencing huge pointers under Win16.  I need the ability to compute logical
relations and distances between 
pointers.

Mark

=======================================================================

/* Copyright (C) 1986-2001 by Digital Mars. $Revision: 1.1.1.1 $ */
#if __SC__ || __RCC__
#pragma once
#endif

#ifndef __HUGEPTR_H
#define __HUGEPTR_H 1

#if __cplusplus
extern "C" {
#endif

#if __INTSIZE == 4

#define hugeptr_cmp(h1,h2) ((h1) - (h2))
#define hugeptr_diff(h1,h2) ((h1) - (h2))
#define hugeptr_add(h1,offset) ((h1) + (offset))

#else

long __pascal hugeptr_diff(void __far *h1,void __far *h2);
void __far * __pascal hugeptr_add(void __far *h1,long offset);

#define hugeptr_cmp(h1,h2) ((long)(h1) - (long)(h2))
#define hugeptr_diff(h1,h2) (hugeptr_diff((h1),(h2)) / sizeof(*h1))
#define hugeptr_add(h,offset) (hugeptr_add(h,(long)offset * sizeof(*h)))

#endif

#if __cplusplus
}
#endif

#endif
Jun 22 2001
parent reply "Walter" <walter digitalmars.com> writes:
It should work fine for win16, dos16, and 286 extended dos. -Walter

Mark Evans wrote in message <1103_993231465 evans>...

There is an include file called HUGEPTR.H which for some reason is not in




I just want to ask whether this is the "approved" method of comparing and



logical relations and distances between

pointers.

Mark

=======================================================================

/* Copyright (C) 1986-2001 by Digital Mars. $Revision: 1.1.1.1 $ */
#if __SC__ || __RCC__
#pragma once
#endif

#ifndef __HUGEPTR_H
#define __HUGEPTR_H 1

#if __cplusplus
extern "C" {
#endif

#if __INTSIZE == 4

#define hugeptr_cmp(h1,h2) ((h1) - (h2))
#define hugeptr_diff(h1,h2) ((h1) - (h2))
#define hugeptr_add(h1,offset) ((h1) + (offset))

#else

long __pascal hugeptr_diff(void __far *h1,void __far *h2);
void __far * __pascal hugeptr_add(void __far *h1,long offset);

#define hugeptr_cmp(h1,h2) ((long)(h1) - (long)(h2))
#define hugeptr_diff(h1,h2) (hugeptr_diff((h1),(h2)) / sizeof(*h1))
#define hugeptr_add(h,offset) (hugeptr_add(h,(long)offset * sizeof(*h)))

#endif

#if __cplusplus
}
#endif

#endif
Jun 22 2001
parent reply Mark Evans <mevans zyvex.com> writes:
Walter,

Which huge-pointer functions are mandatory, and when can I just use normal C
pointer arithmetic.  For example can I do things like the following across
segment boundaries:

char __huge *ptr;
char __huge *buf;
long int i;

buf = _halloc(200000,1); // multiple segment crossings in the buffer
ptr = buf + 50000; // point anywhere in the buffer using normal pointer
arithmetic, no hptr_add
for(i=0;i<(64000*2);i++)
{
    *ptr++ = 'C'; // normal pointer incrementing, no use of hptr_add, may cross
segment boundaries
}


My impression is that I can, unless I want to actually compare two huge
pointers -- in which case hugeptr_diff or hugeptr_cmp would be mandatory.  So
the only truly mandatory functions would 
be the comparison/difference functions, correct?  Under Win16, the preprocessor
variable __INTSIZE == 2, so the second header clause applies.

Thanks,

Mark


On Fri, 22 Jun 2001 12:55:03 -0700, "Walter" <walter digitalmars.com> wrote:

 It should work fine for win16, dos16, and 286 extended dos. -Walter
 
 Mark Evans wrote in message <1103_993231465 evans>...

There is an include file called HUGEPTR.H which for some reason is not in




I just want to ask whether this is the "approved" method of comparing and



 logical relations and distances between

pointers.

Mark

=======================================================================

/* Copyright (C) 1986-2001 by Digital Mars. $Revision: 1.1.1.1 $ */
#if __SC__ || __RCC__
#pragma once
#endif

#ifndef __HUGEPTR_H
#define __HUGEPTR_H 1

#if __cplusplus
extern "C" {
#endif

#if __INTSIZE == 4

#define hugeptr_cmp(h1,h2) ((h1) - (h2))
#define hugeptr_diff(h1,h2) ((h1) - (h2))
#define hugeptr_add(h1,offset) ((h1) + (offset))

#else

long __pascal hugeptr_diff(void __far *h1,void __far *h2);
void __far * __pascal hugeptr_add(void __far *h1,long offset);

#define hugeptr_cmp(h1,h2) ((long)(h1) - (long)(h2))
#define hugeptr_diff(h1,h2) (hugeptr_diff((h1),(h2)) / sizeof(*h1))
#define hugeptr_add(h,offset) (hugeptr_add(h,(long)offset * sizeof(*h)))

#endif

#if __cplusplus
}
#endif

#endif
Jun 22 2001
parent reply "Walter" <walter digitalmars.com> writes:
Yes, that code should work. The hugeptr.h was there before it was added to
the compiler, and was retained for backwards compatibility.

What wasn't done was creating an entire 'huge' memory model with runtime
library, etc.

Mark Evans wrote in message <1103_993238062 evans>...

Walter,

Which huge-pointer functions are mandatory, and when can I just use normal



segment boundaries:

char __huge *ptr;
char __huge *buf;
long int i;

buf = _halloc(200000,1); // multiple segment crossings in the buffer
ptr = buf + 50000; // point anywhere in the buffer using normal pointer




for(i=0;i<(64000*2);i++)
{
    *ptr++ = 'C'; // normal pointer incrementing, no use of hptr_add, may




}


My impression is that I can, unless I want to actually compare two huge



So the only truly mandatory functions would

be the comparison/difference functions, correct?  Under Win16, the




Thanks,

Mark


On Fri, 22 Jun 2001 12:55:03 -0700, "Walter" <walter digitalmars.com>




 It should work fine for win16, dos16, and 286 extended dos. -Walter

 Mark Evans wrote in message <1103_993231465 evans>...

There is an include file called HUGEPTR.H which for some reason is not










 the win16 subfolder.  (Contents appended below.)

I just want to ask whether this is the "approved" method of comparing










 differencing huge pointers under Win16.  I need the ability to compute
 logical relations and distances between

pointers.

Mark

=======================================================================

/* Copyright (C) 1986-2001 by Digital Mars. $Revision: 1.1.1.1 $ */
#if __SC__ || __RCC__
#pragma once
#endif

#ifndef __HUGEPTR_H
#define __HUGEPTR_H 1

#if __cplusplus
extern "C" {
#endif

#if __INTSIZE == 4

#define hugeptr_cmp(h1,h2) ((h1) - (h2))
#define hugeptr_diff(h1,h2) ((h1) - (h2))
#define hugeptr_add(h1,offset) ((h1) + (offset))

#else

long __pascal hugeptr_diff(void __far *h1,void __far *h2);
void __far * __pascal hugeptr_add(void __far *h1,long offset);

#define hugeptr_cmp(h1,h2) ((long)(h1) - (long)(h2))
#define hugeptr_diff(h1,h2) (hugeptr_diff((h1),(h2)) / sizeof(*h1))
#define hugeptr_add(h,offset) (hugeptr_add(h,(long)offset * sizeof(*h)))

#endif

#if __cplusplus
}
#endif

#endif
Jun 22 2001
parent reply Mark Evans <mevans zyvex.com> writes:
Good, I thought so.  In that case, do I still need hugeptr_diff() and
hugeptr_cmp(), or can I just use the minus sign as I would in 32-bit C?  For
example would this work:

char __huge *buf;
char __huge *ptrA;
char __huge *ptrB;
signed long int diff;

buf = _halloc(200000,1);
ptrA = buf + 80000;
ptrB = buf + 120000;
diff = ptrB - ptrA;
printf("The difference is %ld.\n",diff); // should be 40000


I may not need to include HUGEPTR.H at all if the above works OK.

(I do understand completely about the memory model issue and am not asking for
that.)

Thanks,

Mark


On Fri, 22 Jun 2001 15:35:36 -0700, "Walter" <walter digitalmars.com> wrote:

 Yes, that code should work. The hugeptr.h was there before it was added to
 the compiler, and was retained for backwards compatibility.
 
 What wasn't done was creating an entire 'huge' memory model with runtime
 library, etc.
Jun 22 2001
parent "Walter" <walter digitalmars.com> writes:
It should work fine. If you wish to verify it, just write a small stub,
compile it, and obj2asm the result. -Walter

Mark Evans wrote in message <1104_993246193 evans>...

Good, I thought so.  In that case, do I still need hugeptr_diff() and



example would this work:

char __huge *buf;
char __huge *ptrA;
char __huge *ptrB;
signed long int diff;

buf = _halloc(200000,1);
ptrA = buf + 80000;
ptrB = buf + 120000;
diff = ptrB - ptrA;
printf("The difference is %ld.\n",diff); // should be 40000


I may not need to include HUGEPTR.H at all if the above works OK.

(I do understand completely about the memory model issue and am not asking




Thanks,

Mark


On Fri, 22 Jun 2001 15:35:36 -0700, "Walter" <walter digitalmars.com>




 Yes, that code should work. The hugeptr.h was there before it was added







 the compiler, and was retained for backwards compatibility.

 What wasn't done was creating an entire 'huge' memory model with runtime
 library, etc.
Jun 22 2001