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Message-ID: <005a01bf3f4a$248ccbc0$21f838ca@home-computer>
From: "Prashant TR" <prashant_news AT yahoo DOT com>
To: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>,
        "Gareth Williams" <ghw2002tii AT hotmail DOT com>
Cc: "DJGPP Mailing list" <djgpp AT delorie DOT com>
Subject: Re: Setting a variable's selector? - Clarification - I hope.
Date: Sun, 5 Dec 1999 23:02:32 +0530
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Reply-To: djgpp AT delorie DOT com

Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> wrote:

>This probably means that you should use the real-mode interface, since
>mixing 16-bit code with 32-bit code in the DPMI environment is tricky,
>if not impossible.

Out of curiosity, could you give me a brief idea of how it works?
If I ever need to do this, should I first create a descriptor and then
try changing the access rights, or is it something totally different?

Thanks in advance.

>So I think you need to forget about 16-bit PM selectors, and instead
>work via the real-mode interface, using the transfer buffer,
>__dpmi_int, and the other functions that allow to invoke real-mode
>procedures.  If you have problems with doing that, please post
>specific questions.

I've put a portion of the copy of the latest version of the SysInfo I'm
working on. Have a look at this. If you find this interesting, you can
get the entire source from

http://prashanttr.tripod.com/

This code is 16-bit, but my intention is to help you get the basic
idea of how to access PnP device information. This one gives
you a detailed description of the PnP and ISA/PnP devices
(such as your sound card). Maybe I'll need your help to write a
DJGPP version of this.

And please excuse me for this horribly long mail.

Thanks,
Prashant

------------------------------------------
One pound of knowledge requires ten pounds of
common sense to apply it.

/*
* EXTERNAL.H - Contains external functions.
* Copyright (C) 1998, 1999 Prashant TR
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* See the file COPYING.TR for more details.
*/

// ID for this file.
#define _EXTERNAL_H_

// External variables.
#ifndef _PNP_CC_
extern int errflag;

#endif

// PNP structure.
typedef struct _PNP_tag {
char   signature[4];
unsigned char  version;
char  misc[8];
unsigned short (*pnp_entry_point)(...);
unsigned short protected_mode_entry_offset;
char  misc_1[8];
unsigned short bios_selector;
char   misc_3[4];
unsigned short isa_read_port;
char   misc_4[8];
} PNP;

// Function definitions.
void newhandler();
void checkerrors();
int pinrun(const char *, const char *);
FILE *pinseek(const char *, const char *);

----------------------
/*
* PNP.CPP - Contains Plug and Play functions.
* Copyright (C) 1998, 1999 Prashant TR
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* See the file COPYING.TR for more details.
*/

// ID for this file.
#define _PNP_CC_

#include "pnp.h"

FILE *fp;
char cmdline[20];
int errflag = 0;
unsigned char buf1[512], buf2[256], owner[256];
unsigned char pnpname[256], flag;
unsigned short count, isaport = 0, type = 1;
PNP *header;

unsigned _stklen = 0x2000;

// Write any string to the file and check for successfulness.
void writestring(const char *string)
{
if (fprintf(fp, "%s", string) == EOF) {
  errflag = 2;
  checkerrors();
}
}

PNP *get_pnp_entry_point()
{
unsigned short segment, offset, f;
char flag;

// Search for $PNP.
segment = 0xf000;
offset = flag = 0;

do {
  if (!strncmp((char *)MK_FP(segment, offset), "$PnP", 4))
  flag++;
  else offset += 0x10;
} while ((offset) && (!flag));

// Check if actually PnP.
if (flag) {
  flag = 0;
  for(f = 0; f <= 0x20; f++)
  flag += *(char *)MK_FP(segment, offset + f);
  flag = (!flag) ? 1 : 0;
}
return ((offset) ? (PNP *)MK_FP(segment, offset) : NULL);
}

void writepnpinfo()
{
char output[256];
unsigned short f, count;
int irq, dma, portid, mask, masknum, card = 1;

// Get the starting specifier type.
count = 12;
flag = irq = dma = 0;
flag = buf1[count]; // The specifier.

// Process PnP Information.
while (((unsigned char)flag >> 3) != 0xf)
{
  flag = buf1[count]; // The specifier.
  if ((flag & 0x78) == 0x10) {
   sprintf(output, "\n\tDevice Identification         : "
    "%c%c%c%02X%02X\n",
    ((*(unsigned short *)&buf1[count + 1] >> 2) & 0x1f)
     + 0x40,
    (char)((unsigned long)(((((unsigned long)
     *(unsigned short *)&buf1[count + 1]) >> 13)
     & 7)
     | ((buf1[count + 1] & 3) << 3))
     + 0x40),
    (buf1[count + 2] & 0x1f)
     + 0x40,
    buf1[count + 3],
    buf1[count + 4]);
   writestring(output);
   count += 6;
   continue;
  }

  switch (((unsigned char)flag >> 3) - 2) {
   case 0:
   case 1:
   case 4:
   case 5:
   case 8:  // Probably Memory - 8.
    break;
   // IRQ Setting.
   case 2:
    mask = *(unsigned short *)
     &buf1[count + 1];
    masknum = 0;
    do {
     if ((mask >> masknum) & 1) {
      irq++;
      sprintf(output,
       "\tIRQ "
       "Setting"
       " (%03u)"
       "       "
       "      : "
       "%d\n",
       irq,
       masknum);
      writestring(output);
      break;
     }
     masknum++;
    } while (masknum <= 15);
    break;

   // DMA Channel.
   case 3:
    mask = buf1[count + 1];
    masknum = 0;
    do {
     if ((mask >> masknum) & 1) {
      dma++;
      sprintf(output,
       "\tDMA "
       "Channel"
       " (%03u)"
       "       "
       "      : "
       "%d\n",
       dma,
       masknum);
      writestring(output);
      break;
     }
     masknum++;
    } while (masknum <= 7);
    break;

   // I/O Ports.
   case 6:
    sprintf(output, "\tI/O Range       "
     "              : "
     "%04X - %04X\n",
     *(int *)&buf1[count + 4],
     *(int *)&buf1[count + 4] +
     buf1[count + 7] - 1);
    writestring(output);
    break;

   // I/O Ports.
   case 7:
    sprintf(output, "\tI/O Range       "
     "              : "
     "%04X - %04X\n",
     *(int *)&buf1[count + 1],
     *(int *)&buf1[count + 1] +
     buf1[count + 3] - 1);
    writestring(output);
    break;

   default:
    if (!(flag & 0x80)) break;

    // Check if memory type specifier.
    if ((flag & 0xf) == 6) {
     sprintf(output, "\tMemory Range    "
      "              : "
      "%08lX - %08lX\n",
      *(long *)&buf1[count + 4],
      *(unsigned long *)&
       buf1[count + 4] +
      *(unsigned long *)&
       buf1[count + 8]
      - 1);
     writestring(output);
    }

    // Check if Card name specifier.
    if ((flag & 0xf) == 2) {
     char x = buf1[count +
       *(unsigned short *)&
       buf1[count + 1] + 3];

     buf1[count +
      *(unsigned short *)&
      buf1[count + 1] + 3] = 0;

     sprintf(output, (card == 1) ?
      "\tPlug and Play Ca"
      "rd            : "
      "%s\n" :
      "\tPlug and Play De"
      "vice          : "
      "%s\n",
      &buf1[count + 3]);
     writestring(output);

     buf1[count +
      *(unsigned short *)&
      buf1[count + 1] + 3] = x;

     if (card) card = 0;

    }

    // Modify counter and type;
    count += *(unsigned short *)
     &buf1[count + 1] + 2;
    flag &= 0x80;
    break;
  }

  // Increment pointer.
  count += (flag & 7) + 1;
}
}

...
...
...








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