Overlay Spawn Function


    description:
    
    This diskette contains the following library: SPAWNS.
    This is for use with programs written using the small memory model.
    This library contains the following function: spawn, spawnp and
    spawne.

    Spawn.

    This function takes as parameters a program name and any parameters that
    are to be passed to this program. Before executing the new program spawn 
    will swap to either EMS, and or, Disk the current program leaving only a
    small kernel in memory. On termination of the spawned program to function
    will restore the parent from EMS, and or Disk.

    Usage:

	spawn("d:\file_path\file_name","arg1","arg2",NULL);

      arg1, arg2 are pointers to NULL terminated strings.	

     You must supply the full file name i.e "CL.EXE" not "CL".
     The arguement list must be terminated by a NULL.
     the length of all the arguements must not exceed 128 bytes.

    upon invocation spawn will verify that the parameters do not exceed
    128 bytes. It will then save all memory belonging to the current program
    in either EMS or Disk. It will save as much to EMS as it can and will
    then start saving to Disk. After saving everything it shrinks the current
    programs memory usage to about 800 Bytes and invokes the program passed.
    Upon return spawn restores memory from either EMS or Disk. Frees the EMS
    pages and deletes the swap file. Control is then returned back to the
    calling program.

    These functions can be called from 'C' programs only.

    Include stdio.h and stdlib.h in your C code.
    Do not pass pointers to the parents data as arguements to the child
    program.	 	

    spawnp.

    This function will look in the current directory for the program to
    execute. If it does not find it there it will the PATH= environment
    variable. If it finds the program it will invoke spawn.

      usage is spawnp("CL.EXE","arg1","arg2",NULL);

      arg1, arg2 are pointers to NULL terminated strings.	
	
    spawne.
	
	Usage is spawne("C:\\MYPROG.EXE\\","arg1","arg2",NULL,env);

	You must supply the full path and name of the executeable.
	arg1,arg2 are pointers to NULL terminated strings.
        env is of the following form:

	char *env[ ] = {"PROMPT=$P$G",
                        "COMSPEC=C:\\COMMAND.COM",
                        NULL };  
     
    This function will invoke the child program setting its environment	to
    the passed strings. It will then invoke spawn to swap the parent program
    to disk and execute the child
     All these functions return either the child programs return code or -1
     on error. On an error the global external ERRNO will be set to the
     following values.

     2 - Program not found
     3 - Path not found
     5 - Access denied
     8 - Not enough memory

     
    For a $15 registration fee you will receive the Large,Medium and compact
    Model librarys. Please include $2 for postage etc.

	
    send your check to Steve Bridges
		       1391 union street
		       Manchester NH 03104.


    As usual you use this function as is at your own risk.