From: "lewi9908" <lewi9908 AT ghc DOT ctc DOT edu>
Newsgroups: comp.os.msdos.djgpp
Subject: DJGPP Quest: Making Sys Q...
Date: Sun, 23 Feb 2003 21:26:00 -0800
Organization: Posted via Supernews, http://www.supernews.com
Message-ID: <v5jb798vrdeeff@corp.supernews.com>
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000
X-Complaints-To: abuse AT supernews DOT com
Lines: 108
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

I am using djgpp to build an operating system that has a SYS MSG Q. Now I
have been working with this to get it right but it doesn't seem to be
working right. Rather than starting with my current mess of Q code I will
start from the place I got the code it is based on
http://www.planet-source-code.com/xq/ASP/txtCodeId.4996/lngWId.3/qx/vb/scrip
ts/ShowCode.htm. Note this code is made for a build with the standard lib
and I was able to build and run it the WinXP Pro DOS box. Then I converted
it to test it in my kernel. For testing of Q I have made my kernel as small
in features as I need cause other parts are buggy even without the Q.

The features left are:

1) External asm file build with NASM and linked with the kernel c++ obj
file...

[BITS 32]
GLOBAL _ExASM_OutputChar

CR equ 0x0d
LF equ 0x0a

SECTION .text

;void ExASM_OutputChar(char cCharToWrite, unsigned int iVideoMemIndex, BYTE
StrAttrib);
_ExASM_OutputChar:
 push ebp
 mov ebp,esp

 mov ecx, [ebp+0x8]
 mov edx, [ebp+0xc]

OutputChar_StartLoop:
 mov al, cl
 mov byte [edx], al
 inc edx
 mov ebx, [ebp+0x10]
 mov byte [edx], bl

OutputChar_PrintDone:

 mov esp,ebp
 pop ebp
 retn

2) Simple new and delete code...
Header file...

typedef long unsigned int size_t;

void* operator new(size_t bytes);
void operator delete(void* mem);

void* operator new[](size_t bytes);
void operator delete[](void* mem);

Cpp file...
#include "ker.h"

//Next two line are for printing char to screen control by
TempCharIndexForVideoMem...
extern "C" void ExASM_OutputChar(char cCharToWrite, unsigned int
iVideoMemIndex, BYTE StrAttrib);
int TempCharIndexForVideoMem = 0;  //This is elsewhere in the expanded
kernel version...
//Ex how I call the function "ExASM_OutputChar('Q',
0xb8000+(TempCharIndexForVideoMem++ * 2), 2);"

//The rest of new delete...
static char memblock[100];
static char* lastAllocated = memblock;

void* operator new(size_t bytes)
{
 char* r = lastAllocated;
 lastAllocated += bytes/* + sizeof(int)*/;    // save room for size
 //*r++ = bytes;    // save size
 return r;
}

void operator delete(void* mem)
{
 if(mem)
 {
  int size = (int)((int*) mem) - 1;    // retrieve size

  // here, you will need to retrieve the memory block
 }
}

void* operator new[](size_t bytes)
{
 return ::operator new(bytes);
}

void operator delete[](void* mem)
{
 ::operator delete(mem);
}

Now with my features I left in my kernel do you know how I can convert what
was at the link it to work right cause when I add 3 and 5 to the Q print()
give me -1 then I started using pointer to pointer and really got messed
up...

Any help...