I'm trying to print out sizeof() values for some of my structures. They are coming out incorrect. Here is a small table in which I've done this on different platforms: Linux : sizeof(TChannel) = 1460 Windows: sizeof(TChannel) = 1460 8051 : sizeof(TChannel) = 1361 Are there byte-alignment issues perhaps? I have both Linux and Windows defaulting to a 1-byte boundary for byte alignment in structures. Does the 8051 default to something different? Here's my code for the 8051: Debugf( "sizeof(TChannel) = %u\r\n", sizeof( TChannel ) ); I've tried %u, %d, %lu, %bu, %X but can't get the right value. Here's my Debugf() function in case that might be messing things up: void Debugf(BYTE* format, ...) { #ifdef DEBUG xdata BYTE buf[64]; va_list arglist; va_start (arglist,format); vsprintf(buf,format,arglist); va_end (arglist); SendSerialData( buf, strlen( buf ) ); #endif } I don't think the problem is in my SendSerialData() function as that seems to work well. Any ideas?
I wonder why the OP didn't typedef Bool to bit a bit instead of char? I didn't do this because I couldn't get the type 'bit' to be declared in xdata. The compiler choked (I forget the error message). And since I have boolean values in my structures, which are in xdata, BOOL was defined as unsigned char. On the 8051, aligment is to 1 byte thus all structs are "packed". On a 16-bit machine typically padded to 2 bytes, with a 32-bit machine padding to 4 usually. Yes, the following will force MSVC (on a 32-bit Intel machine) to align to 1 byte boundaries, to match that of the 8051. #ifdef _WINDOWS_ #pragma pack (1) #endif structs go here As you might have guessed, this is a common header file that both my GUI on Windows and the firmware on the 8051 share, so I can transfer these structures back and forth via the serial port. And yes, I do all the endian conversion on the GUI side; it works just fine.
I didn't do this because I couldn't get the type 'bit' to be declared in xdata. The compiler choked (I forget the error message). Of course it choked, bit data is a not only an 8051 type but a memory space, that space is at DATA address 0x20 and extends for some number of bytes that can be treated as true bit types. It is a contradiction to attempt an XDATA bit var. For structs (or do you mean C bit-fields?) you must use the type unsigned char for the next most efficient access (remember, you pay a penalty for the signed versions).