test_bit linux

int test_bit(int nr, const volatile void *addr);

#include <stdio.h>
#include <stdint.h>
#include <string.h>

// 模拟 test_bit 函数
int test_bit(int nr, const volatile void *addr) {
    return (1UL & ((const volatile uint32_t *)addr)[nr / 32]) >> (nr % 32);
}

int main() {
    uint32_t bitmap[2] = {0xFFFFFFFF, 0x00000000}; // 64 位的位图，前 32 位全为 1，后 32 位全为 0

    int bit_to_test = 20;
    if (test_bit(bit_to_test, bitmap)) {
        printf("Bit %d is set.\n", bit_to_test);
    } else {
        printf("Bit %d is not set.\n", bit_to_test);
    }

    bit_to_test = 40;
    if (test_bit(bit_to_test, bitmap)) {
        printf("Bit %d is set.\n", bit_to_test);
    } else {
        printf("Bit %d is not set.\n", bit_to_test);
    }

    return 0;
}