B-Tree Structure and Word Search Add-on / Programming Interfaces / Watcom C/C++ for OS/2 (16bit)

FATS - Fast Access Tree System
	Table of Contents
		Programming Interfaces
			Watcom C/C++ for OS/2 (16bit)

Watcom C/C++ for OS/2 (16bit)

OS/2 Libraries FATS_O16.DLL / FATSXO16.DLL

The diskette "FATS for OS/2 (16bit)" contains the dynamic link libraries FATS_O16.DLL (basis version) resp. FATSXO16.DLL (extended version), that must be copied into the system directory of OS/2 :

COPY FATS?O16.DLL \OS2\DLL

The libraries are exporting the following functions:

void _far * _far _pascal FATSLibInit(unsigned int uDatasize, unsigned int uSign);
void _far * _far _pascal FATSLibExit(void _far *lpFatsdata);
unsigned long _pascal FATSLibCall(char _far *szCmnd,int _far *nErrorcode, char _far *szFatsKey, void _far *lpFatsdata)

On the FATS distribution diskette in the directory OS2_16I you find the import libraries FATS_O16.LIB (basis version) resp. FATSXO16.LIB (extended version) that are supported for linking with your programs.

Before you can use the FATS commands in your Watcom C program, you must assign a data area to FATS:

lpFatsdata = FATSLibInit(0, 2);

The first parameter determines the size of the FATS data area. If you indicate a zero here, then the minimum needed storage space is reserved (approx. 18-20 KB). The second parameter intends the assigned programming language, for C this value must equal to 2. The address of the data area is returned in the variable lpFatsdata.

Before terminating the application program you should release the storage area allocated by FATSLibInit. You can do this by calling the function FATSLibExit:

lpFatsdata = FATSLibExit(lpFatsdata);

Although the storage area would be released automatically by the operating system, this instruction is useful, since it closes all FATS files that are still opened.

Calling FATS

FATS commands are executed with the function FATSLibCall:

dwRecno = FATSLibCall(szCmnd, &nErrorcode, szFatsKey, lpFatsdata);

Parameter Usage:

szCmnd Command string (input)
nErrorcode Errorcode (output)
szFatsKey Key value (output)
lpFatsdata Address of FATS data area (input)
Return Value: Record Number

Testprograms

The FATS distribution disk for OS/2 (16bit) contains some test programs in the directory OS2_16I\C\WATCOM that illustrate how you can use the FATS commands in your programs:

tst1_eng.c Test program for Watcom-C for OS/2
rebuild.c Re-Indexing a Data File (commands 'BK', 'DL')

The extended version of FATS contains the following additional test programs:

tst2_eng.c Introduction to the Matchcode Functions
mcsort.c Use of the key-flag with command 'MC'
reindex.c Fast Re-Indexing with the command 'XB'

szCmnd	Command string (input)
nErrorcode	Errorcode (output)
szFatsKey	Key value (output)
lpFatsdata	Address of FATS data area (input)
Return Value:	Record Number

tst1_eng.c	Test program for Watcom-C for OS/2
rebuild.c	Re-Indexing a Data File (commands 'BK', 'DL')

tst2_eng.c	Introduction to the Matchcode Functions
mcsort.c	Use of the key-flag with command 'MC'
reindex.c	Fast Re-Indexing with the command 'XB'