c - how to disable fast frames in ath5k wireless driver -

by default, fast frames enabled in ath5k. (http://wireless.kernel.org/en/users/drivers/ath5k) have found macro disables it

#define ar5k_eeprom_ff_dis(_v)      (((_v) >> 2) & 0x1 

the question do it? replace above line

#define ar5k_eeprom_ff_dis(_v)  1 

?

do compile passing parameter?

the bit-shift expression confuses me. _v variable?

the question more general how deal such macros in drivers. i've seen them in other codes , got confused.

ok, try explain simplified example

#include <stdio.h>  /* print in binary mode */ char *chartobin(unsigned char c) {     static char a[9];     int i;      (i = 0; < 8; i++)           a[7 - i] = (c & (1 << i)) == (1 << i) ? '1' : '0';     a[8] = '\0';     return a; }  int main(void) {     unsigned char u = 0xf;      printf("%s\n", chartobin(u));      u >>= 2; // shift bits 2 positions (to right)     printf("%s\n", chartobin(u));            printf("%s\n", chartobin(u & 0x1)); // check if last bit on      return 0; } 

output:

00001111 00000011 00000001 

do replace above line #define ar5k_eeprom_ff_dis(_v) 1?

nooooo!!

if initialize u 0xb instead of 0xf get:

00001011 00000010 00000000 

as can see (((_v) >> 2) & 0x1 != 1