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C51bugs

This code generate 2 bugs:

#define BUG_TEST 0

typedef char * PCHAR;

typedef struct {
    int I;
    int J;
} A_OLD;

typedef struct {
    int nI;
    int nJ;
} A, *PA;
typedef A xdata * PAx;

A_OLD cAOld;

#if     BUG_TEST == 0   //Normal
int l1 = (PCHAR)&(*(PA)(&cAOld));                                               //Get address of struct
int l2 = ((PCHAR)&((*(PA)(&cAOld)).nI) - (PCHAR)&(*(PA)(&cAOld)));              //Calc offset of member
#elif   BUG_TEST == 1   //Cann't initialize
int l1 = (PCHAR)&(*(PAx)(&cAOld));                                              //Get address of struct
#elif   BUG_TEST == 2   //General fault C51
int l2 = (unsigned int)((PCHAR)&((*(PA)(&cAOld)).nI) - (PCHAR)&(*(PA)(&cAOld)));//Calc offset of member
#endif

Parents

0 Bob Horeck over 22 years ago in reply to Drew Davis

I frequently have the same problem. Here is an example of a header file that I use for generating IDs of text strings that are array subscripts to a table of text messages (which may need translation to other languages). The same method can be used with 'offsetof' to generate a table of indexes.

//  +--------------------------------------------------------------------------+
//  |   TxtTable.h                                                             |
//  |                                                                          |
//  |   If "InModTxtTable" is defined, initializations are performed. To use   |
//  |   this feature, "include" the file twice.  The first time before the     |
//  |   definition of "InModTxtTable", the second time after the definition.   |
//  |                                                                          |
//  +--------------------------------------------------------------------------+


#ifdef  _txttableh
    #ifdef  InModTxtTable
        #undef _txttableh
    #endif
#endif

#ifndef _txttableh
#define _txttableh

#ifdef  InModTxtTable
    #define TxtItem(Id, Text) Text

    code char code *TxtString[] = {
#else
    #define TxtItem(Id, Text) Id

    enum TextStringIds {
#endif


/* --  Text Strings for language conversion  -------------------------------- */

TxtItem ( tidOpErrBase,     "NoneDetected"      ),
TxtItem ( tidMemFailure,    "RAM Failure"       ),
TxtItem ( tidSigFailure,    "Params Reset"      ),
TxtItem ( tidE2MemoryErr,   "E2 Mem Fail"       ),
TxtItem ( tidLocalHBusErr,  "Loc Bus Fail"      ),
TxtItem ( tidSystemHBusErr, "Sys Bus Fail"      ),

/*----------------------------------------------------------------------------*/

#ifdef InModTxtTable
    (void *)0
#else
    MaxTextStringId
#endif
};

#undef  TxtItem

#endif

Reply

0 Bob Horeck over 22 years ago in reply to Drew Davis

//  +--------------------------------------------------------------------------+
//  |   TxtTable.h                                                             |
//  |                                                                          |
//  |   If "InModTxtTable" is defined, initializations are performed. To use   |
//  |   this feature, "include" the file twice.  The first time before the     |
//  |   definition of "InModTxtTable", the second time after the definition.   |
//  |                                                                          |
//  +--------------------------------------------------------------------------+


#ifdef  _txttableh
    #ifdef  InModTxtTable
        #undef _txttableh
    #endif
#endif

#ifndef _txttableh
#define _txttableh

#ifdef  InModTxtTable
    #define TxtItem(Id, Text) Text

    code char code *TxtString[] = {
#else
    #define TxtItem(Id, Text) Id

    enum TextStringIds {
#endif


/* --  Text Strings for language conversion  -------------------------------- */

TxtItem ( tidOpErrBase,     "NoneDetected"      ),
TxtItem ( tidMemFailure,    "RAM Failure"       ),
TxtItem ( tidSigFailure,    "Params Reset"      ),
TxtItem ( tidE2MemoryErr,   "E2 Mem Fail"       ),
TxtItem ( tidLocalHBusErr,  "Loc Bus Fail"      ),
TxtItem ( tidSystemHBusErr, "Sys Bus Fail"      ),

/*----------------------------------------------------------------------------*/

#ifdef InModTxtTable
    (void *)0
#else
    MaxTextStringId
#endif
};

#undef  TxtItem

#endif

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