[Sdcc-user] Accessing the upper byte of an address parameter.

[Harding, T. <tha...@ba...>]

I have a function that needs to access the upper byte of an address. I
am working on writing an interface to a i2c serial eeprom, and I would
like to pass in an address to make the function more user friendly.
Anyway here is the code I have and the errors I get:

unsigned char eeprom_read(char *readAddr) { 
  unsigned char retVal; 
  unsigned char firstByte; 
  unsigned char secondByte; 

  // Calculate first and second bytes. 
  firstByte = (unsigned char)((0xA0) | ((readAddr >> 7) & 0x0E)); 
  secondByte = (unsigned char)readAddr; 

... 

[root@localhost final]# sdcc i2c.c 
i2c.c(52):warning *** 'auto' variable 'retVal' may be used before
initialization at i2c.c(52) 
i2c.c(52):warning *** in function i2c_send_byte unreferenced function
argument : 'sendByte' 
i2c.c(68):warning *** 'auto' variable 'retVal' may be used before
initialization at i2c.c(68) 
i2c.c(77):error   *** invalid operand for shift operator 
i2c.c(77):warning *** left & right types are 
_generic * char ,char 
i2c.c(88):error   *** code not generated for 'eeprom_read' due to
previous errors 

If anyone knows how to get access to just the second byte of this
generic pointer please let me know. I have thought about using the
registers that the compiler uses to pass the argument, but I don't know
how reliable that would be.

Any help or ideas would be great. 

Tyson Harding