How to assign a name to each individual bit in the xdata?

[tom12sg]

Bit assign in xdata

Hi,

Need advice on the following:

I'm using keil for 8051.
Normally I will use a bit for flag test
e.g bit flag_error=0;

How can i use xdata instead? How to assign a name to each individual bit in the xdata?
Please give simple example on how to set/clear/test a particular bit
Is there any easy way?

Regards,

 

[ntfreak]

Re: Bit assign in xdata

Couple of ways:
1. use a struct bitfield - watch bitfield order.

typedef struct tagBit {
unsigned char b0:1;
unsigned char b1:1;
unsigned char b2:1;
unsigned char b3:1;
unsigned char b4:1;
unsigned char b5:1;
unsigned char b6:1;
unsigned char b7:1;
}Bit;

xdata Bit test;
test.b0 = 1;

2. Defind simple access functions on a data byte, eg.

#define SetBit(var,place) (var |= (1<<place))
#define ClrBit(var,place) (var &= ~(1<<place))
#define ValBit(var,place) (var & (1<<place))

#define TEST 0
unsigned chat var1;
SetBit( var1,TEST)

Hope this helps.
Regards
NTFreak