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Is it possible for a function to return a union?
Storing data in the Flash/EEData memory of the ADuC845, is done through operating some SFR registers and page write. I would like to read and write different kind of variables and wounder if its possible to use the same function.
Example: // EEData page address #define SERIAL_NO 0x0000 #define DEV_ADR 0x0010
unsigned long serial_no = 123456789; unsigned int dev_adr = 255;
void main (void) { // saving data write(serial_no, SERIAL_NO); write(dev_adr, DEV_ADR); // reading data serial_no = read(SERIAL_NO); dev_adr = read(DEV_ADR); }
My idea was something like this:
union u { unsigned int ival; unsigned long lval; }
void write(union u data, long adr) { // save data in EEData at address long }
union u read(long adr) { // read data from EEData // and return (???) }
Is it possible to do it this way or perhaps a solution would be the use of pointers but how?
Any suggestions?
"... or perhaps a solution would be the use of pointers but how?"
A more conventional interface is for the read/write routines to deal with data objects of arbitrary size.
#define SERIAL_NO 0x0000 #define DEV_ADR 0x0010 unsigned long serial_no = 123456789; unsigned int dev_adr = 255; void write(unsigned ee_addr, void *p_data, size_t size) { } void read(unsigned ee_addr, void *p_data, size_t size) { } void main (void) { write(SERIAL_NO, &serial_no, sizeof serial_no); write(DEV_ADR, &dev_adr, sizeof dev_addr); read(SERIAL_NO, &serial_no, sizeof serial_no); read(DEV_ADR, &dev_adr, sizeof dev_addr); }