		IOLIB Library Documentation 
 
IOLIB defines all the arithmetic operations, and the following
I/O, heap management, and error reporting functions:
 
 
FUNCTIONS
 
cpm(bc,de) int bc,de;
	The registers BC and DE are set to the values of the
	corresponding arguments, and a BDOS service request
	(CALL to 5) is made. The value returned is the contents
	of A (sign extended).
getchar()
	Echoes and returns one character from the standard
	input, which is initially the keyboard but can be 
	redirected by setargs() in the ARGS library.
putchar(c) char c;
	displays one character on the standard output, which is
	initially the console but can be redirected by setargs()
	in the ARGS library.  Adds LF after CR.  Returns c.
gets(buf) char buf[80];
	Gets a null-terminated string from the standard input.
	If I/O has not been redirected, the string comes from
	the keyboard and standard CP/M editing is permitted. The
	maximum length of the string is fixed at 80 characters.
puts(s) char *s;
	Displays a null-terminated string on the standard
	output, using putchar(). 
fopen(name,mode) char *name,*mode;
	Opens file "name". "mode" is a pointer to a single 
	character (either upper or lower case): "r" for read
	access, "w" for write access, and "a" for appending to 
	an existing file. fopen returns a unit number (int) 
	which must be used for subsequent file accesses. 
	For example...
 
	u=fopen("frodo.c","r")	opens FRODO.C for reading
	character=getc(u)	gets a character from FRODO.C
	u=fopen("sam.c","W")	opens SAM.C for writing
	putc(character,u)	writes a character to SAM.C
 
	Up to three files may be open at once. (If more are
	needed, change NBUFS and BUFLGH in IOLIB.C, compile, 
	and assemble.)
fclose(u) int u;
	Closes the file with the unit number u.
getc(u) int u;
	Returns the next character from the file (not sign
	extended), or -1 at end of file. Line feeds are
	discarded, and control Z (1AH) signals end of file. 
getb(u) int u;
	Return next byte from file (not sign extended), without
	regard to its value, or -1 if at end of file. (Use this
	one to read a COM file.) 
putc(c,u) char c; int u;
	Write character c to a file. If it is a carriage
	return, write a line feed as well. Returns c.
putb(c,u) char c; int u;
	Write byte c to a file, without special handling of
	carriage return. 
fflush(u) int u;
	Flush buffer for unit u (which must be an output
	file) to disk. Called automatically by fclose().
 
alloc(n) int n;
	Returns a pointer to a block of n bytes of memory
	(no error checking).
free(ptr) char *ptr;
	ptr should be one of the pointers returned by alloc.
	That block AND ALL BLOCKS ALLOCATED SINCE THEN are
	returned to the heap.	
avail()
	Returns the number of bytes of memory available for
	the heap AND THE STACK. If you allocate all of it
	and write over the stack, you will cause trouble.
	The safe way to get a big buffer is as follows:
		size=avail()-300;
		where=alloc(size);
			/* initialize if needed... */
		i=0; while(i<size) {where[i]=0;}
 
err(s) char *s;
	Prints "\nERROR" and the message pointed to by s on
	the console, and (if enabled during compilation)
	performs a walkback trace. For example, fopen uses
	the call:
		err("OUT OF DISK BUFFERS");
	The walkback trace lists the functions that have
	been called but have not yet returned, with the
	most recently called function first. Any functions
	compiled without the "profile and trace" option
	simply don't appear in the list.
 
upper(c) char c;
	If c is a lower case character, converts it to upper
	case. Otherwise, it returns c.
 
 
POTENTIAL IMPROVEMENTS
	Allocate buffers from the heap only when they are
	needed (would permit more disk buffers without
	penalizing programs that didn't use them).
	alloc() and free() should permit blocks of memory to be
	allocated and freed in any order.
 
 
AUTHOR
	James R. Van Zandt
	27 Spencer Dr.
	Nashua NH 03062
	603-888-2272
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