Can a variable be mapped to the upper nibble of a byte?

[dan king]

I would like to define a variable to the upper nibble of Port B for the INT_RB interrupt. How can I define this instead of masking out the rest of the entire port B byte? For ex:

#byte discs = PORTB
#bit discs.0 = PORTB.4
#bit discs.1 = PORTB.5
#bit discs.2 = PORTB.6
#bit discs.3 = PORTB.7

Thanks in advance.

Dan

[valemike]

What's wrong with simply doing:

#byte port_b=0x06; // verify actual location in device's datasheet
...
unsigned char discs;
discs = port_b >> 4;

There is no masking necessary here. After a boolean, a char is the next size unit can get.

[dan king]

nothing is wrong with that, as a matter of fact that's how I'm currently doing it. I just wanted to know if there was a way to specify the port bits used as in the following, instead of starting at bit 0.

struct {
BYTE data:4; // bits 0 - 3
BYTE regsel:1; // bit 4
BYTE read:1; // bit 5
} LCD_PORT;

#byte PORTB = 6 // port a = 0x05, b = 0x06

#BYTE LCD_PORT = 6
#BIT LCD_E = PORTB.6 // bit 6
#define LCD_RD LCD_PORT.read
#define LCD_RS LCD_PORT.regsel
#define LCD_DATA LCD_PORT.data