C语言实验二——位运算

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

void lfsr_calculate(uint16_t *reg) {
    uint16_t &x = *reg;
    uint16_t x1 = (x << 15) >> 15;
    uint16_t x2 = (x << 13) >> 15;
    uint16_t x3 = (x << 12) >> 15;
    uint16_t x4 = (x << 10) >> 15;
    uint16_t res = x1 ^ x2 ^ x3 ^ x4;
    x = (x >> 1) + (res << 15);
}

int main() {
    int8_t *numbers = (int8_t*)malloc(sizeof(int8_t) * 65536);
    if (numbers == NULL) {
        printf("Memory allocation failed!");
        exit(1);
    }

    memset(numbers, 0, sizeof(int8_t) * 65536);
    uint16_t reg = 0x1;
    uint32_t count = 0;
    int i;

    do {
        count++;
        numbers[reg] = 1;
        if (count < 24) {
            printf("My number is: %u\n", reg);
        }
        else if (count == 24) {
            printf(" ... etc etc ... \n");
        }

        for (i = 0; i < 32; i++)   //生成一个数要调用32次
            lfsr_calculate(&reg);
    } while (numbers[reg] != 1);

    printf("Got %u numbers before cycling!\n", count);

    if (count == 65535) {
        printf("Congratulations! It works!\n");
    }
    else {
        printf("Did I miss something?\n");
    }

    free(numbers);

    return 0;
}