W98, CW6
A newbie question..
I have tried to construct code for a Sat Form Extension to calculate the CRC
for a string. I cobble together the following code and as I am not "C"
fluent I am stuck. Anyone please able to help me out. I spent much time
looking at the square root example and others examples, read the books and
just getting nowhere. Please no flame just a little help this is a last
resort. Where I going wrong?? or just where I can get tutorial on writing
extension in CW.
Thank for any help
//
// MAIN.C - CRC extension
//
// This file is a part of the Satellite Forms product.
//
// You can use it as a starting point for your own Satellite
// Forms extensions.
//
// This file is the proprietary property and information
// of Puma Technology, Inc. No part of it can be used, reproduced
// or distributed in any form without express prior written
// consent from Puma Technology, Inc.
//
// Copyright (c) 1997-99 Puma Technology, Inc. All rights reserved.
//
// $Workfile: Main.c $
// $Revision: 8 $
// $Modtime: 5/24/99 4:07p $
//
#include <Pilot.h>
#include "SFExt.h"
//
// EVENT HANDLERS
//
CBOOL OnExtensionLoad();
void OnSfxNotify();
void OnExtensionUnload();
//
// METHODS
//
#define ABOUTBOX 0
#define CRC16 1
//
// PROTOTYPES
//
/* none */
//
// GLOBAL DATA
//
// Your extension cannot use globals or statics directly.
// All data that would normally be in globals should
// be defined in a struct as below and then allocated
// in OnExtensionLoad(). Global data is shared between
// all instances of an SFX control.
//
// Note: Use as few globals as possible. Remember, dynamic
// memory is a scarce resource on the PalmPilot.
//
typedef struct
{
int GlobalOne;
int GlobalTwo;
// etc ...
} EXTENSION_GLOBALS;
#define GLOBALS ( *((EXTENSION_GLOBALS *) SF_GetGlobalPtr()) )
//
// INSTANCE DATA
//
// If your extension is an SFX control, you may want to
// allocate instance data to represent the state of
// each control. For example, if you implement a SFX
// radio button, the user will probably put more than
// one on a form at a time. Allocate instance data to
// save the state of each button instance so that each
// instance can have a different state. Allocation of
// instance data usually occurs in OnFormAfterOpen().
// Freeing of the data is usually done in OnBeforeFormClose().
//
// Note: Plug-ins do not allocate instance data because
// there can only be one instance of a plug-in.
//
typedef struct
{
int InstanceData1;
int InstanceData2;
// etc ...
} INSTANCE_DATA;
#define INSTDATA ( *((INSTANCE_DATA *) SF_GetInstanceDataPtr()) )
//
// IMPLEMENTATION
//
// Extension loaded entry point
CBOOL OnExtensionLoad()
{
// void *pGlobals;
// This entry point is called when an application
// that contains this extension is loaded. Typically,
// this function does the following things:
//
// 1) Allocate space for any globals your extension
// requires (optional).
//
// 2) Install handlers for events you would like to
// handle (optional).
//
// Set up globals
//
// allocate globals area and set pointer to it
// pGlobals = SF_xmalloc(sizeof(EXTENSION_GLOBALS));
// SF_SetGlobalPtr(pGlobals);
// clear globals so they have a known initial state
//SF_memset(pGlobals, 0, sizeof(EXTENSION_GLOBALS));
// initialize globals
//
// Install handlers for events we care about
//
SF_InstallHandler(SF_HANDLER_ONSFXNOTIFY, OnSfxNotify);
SF_InstallHandler(SF_HANDLER_ONEXTUNLOAD, OnExtensionUnload);
// success
return TRUE;
}
// Extension Unload handler
void OnExtensionUnload()
{
// Unload is called for all instances. Check &GLOBALS before freeing.
if (&GLOBALS)
{
// we've allocated globals - free them
SF_xfree(&GLOBALS);
// mark as free
SF_SetGlobalPtr(NULL);
}
}
//
// Script engine notification handler
//
// All methods and notifications come through this function.
//
// If this extension has methods or is an SFX control, you need
// to implement this function.
//
void OnSfxNotify(
long NotifyCode,
DWORD Param)
{
if (NotifyCode < SFXNOTIFY_FIRSTUSERMETHOD)
{
//no system notifications for plugins
}
else
{
// user extension methods
//
// NotifyCode: function index specified in .INF file
//
// Param: actual number of params pushed on eval stack
// (used by variable argument list methods)
switch (NotifyCode)
{
case 0: // ABOUTBOX
SF_InfoMsg(
"CRC Extension\n"
"Version 1.0\n"
break;
case 1: //CRC()
{
//set to input string
char text1;
SF_ScriptPopString(text1);
// string=SF_ScriptPopString();
text1 = Crc16Calc();
SF_ScriptPushVarString(CRC);
}
default:
SF_InfoMsgInt("Internal error: Unknown method called - ", NotifyCode);
break;
}
}
}
#include "PalmPack.h"
#include <BuildRules.h>
// Include Pilot elementary data types
#include <Common.h>
// Include prototypes for this module
#include "PalmPackPop.h"
/***************************************************************************
************
* FUNCTION: Crc16CalcBlock
*
* DESCRIPTION: Calculate the 16-bit CRC of a data block using the table
lookup method.
*
* PARAMETERS:
* bufP -- pointer to the data buffer;
* count -- the number of bytes in the buffer;
* crc -- the seed crc value; pass 0 the first time
* function is called, pass in new crc result
* as more data is added to packet and crc is updated.
* RETURNS:
* A 16-bit CRC for the data buffer.
*
****************************************************************************
********/
Crc16Calc (VoidPtr bufP, Word count, Word crc16)
{
register BytePtr byteP = (BytePtr)bufP;
WordPtr crctt = (WordPtr)crctt_16; // CRC translation table
//
// Calculate the 16 bit CRC using the table lookup method.
//
if ( count ) {
do {
crc = (crc << 8) ^ crctt[ (Byte)((crc >> 8) ^ *byteP++) ];
} while ( --count );
}
return( crc& 0xffff );
}
// This is the lookup table used when performing the 16-bit CRC calculation.
//
static Word crctt_16[ 256 ] =
{
0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50A5, 0x60C6, 0x70E7,
0x8108, 0x9129, 0xA14A, 0xB16B, 0xC18C, 0xD1AD, 0xE1CE, 0xF1EF,
0x1231, 0x0210, 0x3273, 0x2252, 0x52B5, 0x4294, 0x72F7, 0x62D6,
0x9339, 0x8318, 0xB37B, 0xA35A, 0xD3BD, 0xC39C, 0xF3FF, 0xE3DE,
0x2462, 0x3443, 0x0420, 0x1401, 0x64E6, 0x74C7, 0x44A4, 0x5485,
0xA56A, 0xB54B, 0x8528, 0x9509, 0xE5EE, 0xF5CF, 0xC5AC, 0xD58D,
0x3653, 0x2672, 0x1611, 0x0630, 0x76D7, 0x66F6, 0x5695, 0x46B4,
0xB75B, 0xA77A, 0x9719, 0x8738, 0xF7DF, 0xE7FE, 0xD79D, 0xC7BC,
0x48C4, 0x58E5, 0x6886, 0x78A7, 0x0840, 0x1861, 0x2802, 0x3823,
0xC9CC, 0xD9ED, 0xE98E, 0xF9AF, 0x8948, 0x9969, 0xA90A, 0xB92B,
0x5AF5, 0x4AD4, 0x7AB7, 0x6A96, 0x1A71, 0x0A50, 0x3A33, 0x2A12,
0xDBFD, 0xCBDC, 0xFBBF, 0xEB9E, 0x9B79, 0x8B58, 0xBB3B, 0xAB1A,
0x6CA6, 0x7C87, 0x4CE4, 0x5CC5, 0x2C22, 0x3C03, 0x0C60, 0x1C41,
0xEDAE, 0xFD8F, 0xCDEC, 0xDDCD, 0xAD2A, 0xBD0B, 0x8D68, 0x9D49,
0x7E97, 0x6EB6, 0x5ED5, 0x4EF4, 0x3E13, 0x2E32, 0x1E51, 0x0E70,
0xFF9F, 0xEFBE, 0xDFDD, 0xCFFC, 0xBF1B, 0xAF3A, 0x9F59, 0x8F78,
0x9188, 0x81A9, 0xB1CA, 0xA1EB, 0xD10C, 0xC12D, 0xF14E, 0xE16F,
0x1080, 0x00A1, 0x30C2, 0x20E3, 0x5004, 0x4025, 0x7046, 0x6067,
0x83B9, 0x9398, 0xA3FB, 0xB3DA, 0xC33D, 0xD31C, 0xE37F, 0xF35E,
0x02B1, 0x1290, 0x22F3, 0x32D2, 0x4235, 0x5214, 0x6277, 0x7256,
0xB5EA, 0xA5CB, 0x95A8, 0x8589, 0xF56E, 0xE54F, 0xD52C, 0xC50D,
0x34E2, 0x24C3, 0x14A0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
0xA7DB, 0xB7FA, 0x8799, 0x97B8, 0xE75F, 0xF77E, 0xC71D, 0xD73C,
0x26D3, 0x36F2, 0x0691, 0x16B0, 0x6657, 0x7676, 0x4615, 0x5634,
0xD94C, 0xC96D, 0xF90E, 0xE92F, 0x99C8, 0x89E9, 0xB98A, 0xA9AB,
0x5844, 0x4865, 0x7806, 0x6827, 0x18C0, 0x08E1, 0x3882, 0x28A3,
0xCB7D, 0xDB5C, 0xEB3F, 0xFB1E, 0x8BF9, 0x9BD8, 0xABBB, 0xBB9A,
0x4A75, 0x5A54, 0x6A37, 0x7A16, 0x0AF1, 0x1AD0, 0x2AB3, 0x3A92,
0xFD2E, 0xED0F, 0xDD6C, 0xCD4D, 0xBDAA, 0xAD8B, 0x9DE8, 0x8DC9,
0x7C26, 0x6C07, 0x5C64, 0x4C45, 0x3CA2, 0x2C83, 0x1CE0, 0x0CC1,
0xEF1F, 0xFF3E, 0xCF5D, 0xDF7C, 0xAF9B, 0xBFBA, 0x8FD9, 0x9FF8,
0x6E17, 0x7E36, 0x4E55, 0x5E74, 0x2E93, 0x3EB2, 0x0ED1, 0x1EF0
};
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