C/C++ bit-op test_bit,set_bit,clear

C/C++ bit-op test_bit,set_bit,clear_bit like linux kernel

代碼:



/* Set __SHIFT bit */
void set_bit(uint8_t __SHIFT, uint32_t *var_addr)
{
    *(var_addr) |= ( 0x1UL << __SHIFT);
}

/* Clear __SHIFT bit */
void clear_bit(uint8_t __SHIFT, uint32_t *var_addr)
{
    *(var_addr) &= ~( 0x1UL << __SHIFT);
}

/* Test __SHIFT bit */
uint8_t test_bit(uint8_t __SHIFT, uint32_t *var_addr)
{
    return (*(var_addr) >> __SHIFT) & 0x1UL;
}

void main(void)
{

    uint32_t a = 0x0000feef;


    set_bit( 8,  &a);
    printf("%s: 0x%x\n", __func__, a);
    printf("%s: test bit 8 == %d\n", __func__, test_bit(8, &a));

    clear_bit( 8,  &a);
    printf("%s: 0x%x\n", __func__, a);
    printf("%s: test bit 8 == %d\n", __func__, test_bit(8, &a));

    return;
}

=============================

$ ./a.out

main: 0xffef
main: test bit 8 == 1

main: 0xfeef
main: test bit 8 == 0