自定义校验和算法

问：

最近将一些旧的 MASM 校验和代码移植到 C 中。

MASM 代码用于计算缓冲区或文件的校验和。

我很好奇它类似于什么算法？

下面是 C 语言中正确的等效逻辑： 演示

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

uint32_t computeChecksum(uint8_t *data, size_t dataLength) {
    uint32_t checksum = 0;
    int rotateBits = 0;

    for (size_t i = 0; i < dataLength; i += 4) {
        // Process data in 32-bit chunks.
        uint32_t chunk = *(uint32_t*)(data + i);
        // Perform the ROL operation.
        chunk = (chunk << rotateBits) | (chunk >> (32 - rotateBits));
        // XORs the rotated chunk with a running checksum.
        checksum ^= chunk;
        // The number of bit positions the data is rotated increases by 1
        // for each subsequent chunk and wraps around after 32.
        rotateBits = (rotateBits + 1) % 32;
    }

    return checksum;
}

int main() {
    uint8_t data[32] = {
        0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
        0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x10,
        0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
        0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20
    };

    uint32_t checksum = computeChecksum(data, sizeof(data));
    printf("Checksum: 0x%08X\n", checksum);

    return 0;
}