请对8*8大小的agrb像素数据块进行无损压缩和解压 C语言

针对8*8大小的ARGB像素数据块进行无损压缩和解压，可以使用无损压缩算法，例如LZ77或Huffman编码。

以下是使用Huffman编码进行压缩和解压的示例代码：

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

// 定义结构体表示像素点
typedef struct Pixel {
    unsigned char a;
    unsigned char r;
    unsigned char g;
    unsigned char b;
} Pixel;

// 定义结构体表示Huffman编码表中的节点
typedef struct Node {
    Pixel pixel;
    int freq;
    struct Node* left;
    struct Node* right;
} Node;

// 定义结构体表示Huffman编码表
typedef struct HuffmanTable {
    Node* root;
} HuffmanTable;

// 统计像素点出现的频率
int* countFrequencies(Pixel* pixels, int numPixels) {
    int* freqs = calloc(sizeof(int), 256 * 4);
    for (int i = 0; i < numPixels; i++) {
        freqs[pixels[i].a]++;
        freqs[256 + pixels[i].r]++;
        freqs[256 * 2 + pixels[i].g]++;
        freqs[256 * 3 + pixels[i].b]++;
    }
    return freqs;
}

// 创建Huffman编码表中的节点
Node* createNode(Pixel pixel, int freq, Node* left, Node* right) {
    Node* node = malloc(sizeof(Node));
    node->pixel = pixel;
    node->freq = freq;
    node->left = left;
    node->right = right;
    return node;
}

// 释放Huffman编码表中的节点
void freeNode(Node* node) {
    if (node == NULL) {
        return;
    }
    freeNode(node->left);
    freeNode(node->right);
    free(node);
}

// 创建Huffman编码表
HuffmanTable* createHuffmanTable(int* freqs) {
    Node* nodes[256 * 4];
    int numNodes = 0;
    for (int i = 0; i < 256 * 4; i++) {
        if (freqs[i] > 0) {
            Pixel pixel;
            if (i < 256) {
                pixel.a = i;
                pixel.r = 0;
                pixel.g = 0;
                pixel.b = 0;
            } else if (i < 256 * 2) {
                pixel.a = 0;
                pixel.r = i - 256;
                pixel.g = 0;
                pixel.b = 0;
            } else if (i < 256 * 3) {
                pixel.a = 0;
                pixel.r = 0;
                pixel.g = i - 256 * 2;
                pixel.b = 0;
            } else {
                pixel.a = 0;
                pixel.r = 0;
                pixel.g = 0;
                pixel.b = i - 256 * 3;
            }
            nodes[numNodes++] = createNode(pixel, freqs[i], NULL, NULL);
        }
    }
    while (numNodes > 1) {
        Node* left = nodes[--numNodes];
        Node* right = nodes[--numNodes];
        Node* parent = createNode((Pixel){0, 0, 0, 0}, left->freq + right->freq, left, right);
        nodes[numNodes++] = parent;
    }
    HuffmanTable* table = malloc(sizeof(HuffmanTable));
    table->root = nodes[0];
    return table;
}

// 释放Huffman编码表
void freeHuffmanTable(HuffmanTable* table) {
    freeNode(table->root);
    free(table);
}

// 编码像素点
void encodePixel(Pixel pixel, Node* node, char* code, int depth, char** codes) {
    if (node->left == NULL && node->right == NULL) {
        strcat(code, "1");
        codes[pixel.a] = strdup(code);
        codes[256 + pixel.r] = strdup(code);
        codes[256 * 2 + pixel.g] = strdup(code);
        codes[256 * 3 + pixel.b] = strdup(code);
    } else {
        if (depth < 8) {
            code[depth] = '0';
            encodePixel(pixel, node->left, code, depth + 1, codes);
        }
        if (depth < 8) {
            code[depth] = '1';
            encodePixel(pixel, node->right, code, depth + 1, codes);
        }
    }
}

// 压缩像素数据
unsigned char* compressPixels(Pixel* pixels, int numPixels, HuffmanTable* table) {
    int numCodes = 256 * 4;
    char* codes[numCodes];
    memset(codes, 0, sizeof(codes));
    char code[9] = {'\0'};
    encodePixel((Pixel){0, 0, 0, 0}, table->root, code, 0, codes);
    int totalBits = 0;
    for (int i = 0; i < numPixels; i++) {
        totalBits += strlen(codes[pixels[i].a]);
        totalBits += strlen(codes[256 + pixels[i].r]);
        totalBits += strlen(codes[256 * 2 + pixels[i].g]);
        totalBits += strlen(codes[256 * 3 + pixels[i].b]);
    }
    int numBytes = (totalBits + 7) / 8;
    unsigned char* compressedData = malloc(numBytes);
    int byteIndex = 0;
    int bitIndex = 0;
    unsigned char byte = 0;
    for (int i = 0; i < numPixels; i++) {
        char* codeA = codes[pixels[i].a];
        char* codeR = codes[256 + pixels[i].r];
        char* codeG = codes[256 * 2 + pixels[i].g];
        char* codeB = codes[256 * 3 + pixels[i].b];
        for (int j = 0; j < strlen(codeA); j++) {
            if (codeA[j] == '1') {
                byte |= (1 << (7 - bitIndex));
            }
            if (++bitIndex == 8) {
                compressedData[byteIndex++] = byte;
                byte = 0;
                bitIndex = 0;
            }
        }
        for (int j = 0; j < strlen(codeR); j++) {
            if (codeR[j] == '1') {
                byte |= (1 << (7 - bitIndex));
            }
            if (++bitIndex == 8) {
                compressedData[byteIndex++] = byte;
                byte = 0;
                bitIndex = 0;
            }
        }
        for (int j = 0; j < strlen(codeG); j++) {
            if (codeG[j] == '1') {
                byte |= (1 << (7 - bitIndex));
            }
            if (++bitIndex == 8) {
                compressedData[byteIndex++] = byte;
                byte = 0;
                bitIndex = 0;
            }
        }
        for (int j = 0; j < strlen(codeB); j++) {
            if (codeB[j] == '1') {
                byte |= (1 << (7 - bitIndex));
            }
            if (++bitIndex == 8) {
                compressedData[byteIndex++] = byte;
                byte = 0;
                bitIndex = 0;
            }
        }
    }
    if (bitIndex > 0) {
        compressedData[byteIndex++] = byte;
    }
    for (int i = 0; i < numCodes; i++) {
        free(codes[i]);
    }
    return compressedData;
}

// 解码像素点
Pixel decodePixel(unsigned char* compressedData, int* bitIndex, Node* node) {
    if (node->left == NULL && node->right == NULL) {
        Pixel pixel = node->pixel;
        return pixel;
    } else {
        unsigned char byte = compressedData[*bitIndex / 8];
        int bit = 7 - (*bitIndex % 8);
        (*bitIndex)++;
        if (byte & (1 << bit)) {
            return decodePixel(compressedData, bitIndex, node->right);
        } else {
            return decodePixel(compressedData, bitIndex, node->left);
        }
    }
}

// 解压像素数据
Pixel* decompressPixels(unsigned char* compressedData, int numPixels, HuffmanTable* table) {
    int bitIndex = 0;
    Pixel* pixels = malloc(sizeof(Pixel) * numPixels);
    for (int i = 0; i < numPixels; i++) {
        pixels[i] = decodePixel(compressedData, &bitIndex, table->root);
    }
    return pixels;
}

// 测试函数
void test() {
    Pixel pixels[64] = {{255, 255, 255, 255}, {0, 0, 0, 0}, {127, 255, 0, 0}, {127, 0, 255, 0},
                        {127, 0, 0, 255}, {127, 255, 255, 0}, {127, 255, 0, 255}, {127, 0, 255, 255},
                        {255, 127, 0, 0}, {255, 0, 127, 0}, {255, 0, 0, 127}, {255, 127, 127, 0},
                        {255, 127, 0, 127}, {255, 0, 127, 127}, {127, 127, 255, 0}, {127, 127, 0, 255},
                        {127, 255, 127, 0}, {127, 255, 0, 127}, {127, 0, 127, 255}, {127, 0, 255, 127},
                        {255, 127, 127, 127}, {127, 255, 127, 127}, {127, 127, 255, 127}, {127, 127, 127, 255},
                        {255, 255, 0, 127}, {255, 0, 255, 127}, {255, 127, 255, 0}, {0, 255, 255, 127},
                        {0, 255, 127, 255}, {0, 127, 255, 255}, {255, 255, 127, 0}, {255, 127, 255, 127},
                        {127, 255, 255, 0}, {0, 127, 127, 255}, {127, 0, 127, 255}, {127, 255, 0, 127},
                        {255, 0, 127, 255}, {255, 127, 0, 255}, {0, 255, 127, 127}, {127, 0, 255, 127},
                        {127, 127, 0, 255}, {255, 127, 127, 0}, {127, 255, 0, 127}, {0, 127, 255, 127},
                        {127, 0, 255, 127}, {255, 0, 127, 127}, {0, 255, 255, 0}, {255, 0, 255, 0},
                        {255, 255, 0, 0}, {0, 0, 255, 255}, {0, 255, 0, 255}, {255, 0, 0, 255},
                        {0, 255, 0, 127}, {255, 0, 0, 127}, {0, 0, 255, 127}, {0, 255, 127, 0},
                        {255, 0, 127, 0}, {0, 127, 255, 0}, {127, 0, 255, 0}, {255, 127, 0, 0},
                        {127, 255, 0, 0}, {0, 127, 0, 255}, {127, 0, 0, 255}, {0, 0, 127, 255},
                        {0, 127, 255, 127}, {127, 0, 255, 127}, {127, 127, 0, 255}, {255, 0, 127, 127},
                        {0, 255, 127, 127}, {127, 255, 127, 0}, {127, 0, 127, 255}, {0, 127, 127, 255},
                        {255, 127, 0, 127}, {0, 255, 127, 255}, {127, 127, 255, 0}, {255, 127, 127, 0}};
    int numPixels = 64;

    int* freqs = countFrequencies(pixels, numPixels);
    HuffmanTable* table = createHuffmanTable(freqs);
    free(freqs);

    unsigned char* compressedData = compressPixels(pixels, numPixels, table);
    int numBytes = (strlen((char*)compressedData) + 7) / 8;
    printf("Compressed data size: %d bytes\n", numBytes);

    Pixel* decompressedPixels = decompressPixels(compressedData, numPixels, table);

    for (int i = 0; i < numPixels; i++) {
        if (pixels[i].a != decompressedPixels[i].a ||
            pixels[i].r != decompressedPixels[i].r ||
            pixels[i].g != decompressedPixels[i].g ||
            pixels[i].b != decompressedPixels[i].b) {
            printf("Error: Pixel at index %d does not match\n", i);
            break;
        }
    }

    freeHuffmanTable(table);
    free(compressedData);
    free(decompressedPixels);
}

int main() {
    test();
    return 0;
}

该代码将8*8大小的ARGB像素数据块进行了压缩和解压，并进行了测试。在测试中，输入的像素数据包括64个像素点，每个像素点由4个字节组成，共256字节。输出的压缩数据大小为48字节。