void wreeprom(unsigned short ads, unsigned char c)
{
	EECON |= (1<<1);		/* EEE */
	*((unsigned char xdata *)ads) = c;
	EECON = 0x54;			/* SPECIAL SEQUENCE */
	EECON = 0xA4;
	while (EECON & (1<<0)); 	/* EEBUSY */
	EECON = 0x00;			/* brute force */
}
 

There are no function pointers. I have just cast 'ads' as an 8051 'xdata' because the function actually is designed for other processors.

The (SFR & (1<<SFR_BIT)) syntax is just portable C code. So I presume that the following will be specific for some 8051 C compilers.

void wreeprom(unsigned char xdata *ads, unsigned char c)
{
	EEE = 1;        	/* EEE */
	*ads = c;               /* needs no cast cos in signature */
	EECON = 0x54;		/* SPECIAL SEQUENCE */
	EECON = 0xA4;
	while (EEBUSY);         /* EEBUSY */
	EECON = 0x00;		/* brute force */
}

 

and the equivalent read function:

unsigned char rdeeprom(unsigned char xdata *ads)
{
	unsigned char c;
	EEE = 1;		/* EEE */
	c = *ads;               /* no cast needed */
	EEE = 0;		/* EEE */
	return c;
}

 

You can of course use macros for both of these functions. However the compiler will not know whether you are trying to use a non-xdata 'ads'.

I still have not checked the data sheet. The 5131 may or may not worry if there is an interruption between the two SPECIAL instructions. If you do not use IRQs, you do not have to disable them.

David.