dosemu.h

Embedded magazine source code. this is the source code in the year 1989

/*
   MS-DOS Emulation for Embedded Systems
   Copyright (C) 1989 Paradigm Systems.  All rights reserved.
*/

#if   !defined(_DOS_EMULATION)

#define  _DOS_EMULATION

/*
//    Some commonly emulated DOS functions
*/

#define  DOS_TERMINATE        0x00
#define  DOS_DIRECTIO         0x06
#define  DOS_GETSTATUS        0x0b
#define  DOS_SETVECTOR        0x25
#define  DOS_VERSION          0x30
#define  DOS_GETVECTOR        0x35
#define  DOS_READ             0x3f
#define  DOS_WRITE            0x40
#define  DOS_IOCTL            0x44
#define  DOS_ALLOC            0x48
#define  DOS_FREE             0x49
#define  DOS_REALLOC          0x4a
#define  DOS_EXIT             0x4c


/*
//    Define the format of the DOS memory control block (MCB).  Only the
//    id and size fields need be implemented since the all memory is assumed
//    to be used by a single application.  If a multitasking system is built,
//    placing the task id in the owner field allows freeing the memory owned
//    by the task when it exits.  An id field of 0 is used to mark an unused
//    block.
//
//    The layout in memory consists of an MCB followed by the memory block.
//    The allocator returns to the caller the segment of the block which
//    can be decremented to find the corresponding MCB.
*/

typedef  struct   {
            BYTE     id ;        /* 'M' or 'Z' */
            WORD     owner ;     /* Application PID or PSP */
            WORD     size ;      /* Size in paragraphs */
         } MCB ;

/*
//    Function prototype declarations
*/
void  interrupt   Int21Handler(WORD, WORD, WORD, WORD, WORD, WORD, 
                                 WORD, WORD, WORD, WORD, WORD, WORD) ;

#endif