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

#define M11 7
#define M12 12
#define M13 17
#define M14 22
#define M21 5
#define M22 9
#define M23 14
#define M24 20
#define M31 4
#define M32 11
#define M33 16
#define M34 23
#define M41 6
#define M42 10
#define M43 15
#define M44 21

#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

#define ROL(m, n) (((m) << (n)) | ((m) >> (32-(n))))

#define FF(a, b, c, d, m, s, t) { (a) += F((b), (c), (d)) + (m) + (unsigned int)(t); (a) = ROL((a), (s)) + (b); }
#define GG(a, b, c, d, m, s, t) { (a) += G((b), (c), (d)) + (m) + (unsigned int)(t); (a) = ROL((a), (s)) + (b); }
#define HH(a, b, c, d, m, s, t) { (a) += H((b), (c), (d)) + (m) + (unsigned int)(t); (a) = ROL((a), (s)) + (b); }
#define II(a, b, c, d, m, s, t) { (a) += I((b), (c), (d)) + (m) + (unsigned int)(t); (a) = ROL((a), (s)) + (b); }

typedef struct {
    unsigned int state[4];
    unsigned int count[2];
    unsigned char buffer[64];
} Context;

inline void Encode(unsigned char * output, unsigned int * input, int len) {
    unsigned int i, j;
    for (i = 0, j = 0; j < len; i++, j += 4) {
        output[j] = (unsigned char) (input[i] & 0xff);
        output[j + 1] = (unsigned char) ((input[i] >> 8) & 0xff);
        output[j + 2] = (unsigned char) ((input[i] >> 16) & 0xff);
        output[j + 3] = (unsigned char) ((input[i] >> 24) & 0xff);
    }
}

inline void Decode(unsigned int * output, unsigned char * input, int len) {
    unsigned int i, j;
    for (i = 0, j = 0; j < len; i++, j += 4) {
        output[i] = ((unsigned int) input[j]) |
            (((unsigned int) input[j + 1]) << 8) |
            (((unsigned int) input[j + 2]) << 16) |
            (((unsigned int) input[j + 3]) << 24);
    }
}

inline void Transform(unsigned int state[4], unsigned char block[64]) {
    unsigned int a = state[0], b = state[1], c = state[2], d = state[3], m[16];
    Decode(m, block, 64);
    /* Round 1 */
    FF(a, b, c, d, m[0],  M11, 0xd76aa478);   /* 1  */
    FF(d, a, b, c, m[1],  M12, 0xe8c7b756);   /* 2  */
    FF(c, d, a, b, m[2],  M13, 0x242070db);   /* 3  */
    FF(b, c, d, a, m[3],  M14, 0xc1bdceee);   /* 4  */
    FF(a, b, c, d, m[4],  M11, 0xf57c0faf);   /* 5  */
    FF(d, a, b, c, m[5],  M12, 0x4787c62a);   /* 6  */
    FF(c, d, a, b, m[6],  M13, 0xa8304613);   /* 7  */
    FF(b, c, d, a, m[7],  M14, 0xfd469501);   /* 8  */
    FF(a, b, c, d, m[8],  M11, 0x698098d8);   /* 9  */
    FF(d, a, b, c, m[9],  M12, 0x8b44f7af);   /* 10 */
    FF(c, d, a, b, m[10], M13, 0xffff5bb1);   /* 11 */
    FF(b, c, d, a, m[11], M14, 0x895cd7be);   /* 12 */
    FF(a, b, c, d, m[12], M11, 0x6b901122);   /* 13 */
    FF(d, a, b, c, m[13], M12, 0xfd987193);   /* 14 */
    FF(c, d, a, b, m[14], M13, 0xa679438e);   /* 15 */
    FF(b, c, d, a, m[15], M14, 0x49b40821);   /* 16 */
    /* Round 2 */
    GG(a, b, c, d, m[1],  M21, 0xf61e2562);   /* 17 */
    GG(d, a, b, c, m[6],  M22, 0xc040b340);   /* 18 */
    GG(c, d, a, b, m[11], M23, 0x265e5a51);   /* 19 */
    GG(b, c, d, a, m[0],  M24, 0xe9b6c7aa);   /* 20 */
    GG(a, b, c, d, m[5],  M21, 0xd62f105d);   /* 21 */
    GG(d, a, b, c, m[10], M22, 0x2441453);    /* 22 */
    GG(c, d, a, b, m[15], M23, 0xd8a1e681);   /* 23 */
    GG(b, c, d, a, m[4],  M24, 0xe7d3fbc8);   /* 24 */
    GG(a, b, c, d, m[9],  M21, 0x21e1cde6);   /* 25 */
    GG(d, a, b, c, m[14], M22, 0xc33707d6);   /* 26 */
    GG(c, d, a, b, m[3],  M23, 0xf4d50d87);   /* 27 */
    GG(b, c, d, a, m[8],  M24, 0x455a14ed);   /* 28 */
    GG(a, b, c, d, m[13], M21, 0xa9e3e905);   /* 29 */
    GG(d, a, b, c, m[2],  M22, 0xfcefa3f8);   /* 30 */
    GG(c, d, a, b, m[7],  M23, 0x676f02d9);   /* 31 */
    GG(b, c, d, a, m[12], M24, 0x8d2a4c8a);   /* 32 */
    /* Round 3 */
    HH(a, b, c, d, m[5],  M31, 0xfffa3942);   /* 33 */
    HH(d, a, b, c, m[8],  M32, 0x8771f681);   /* 34 */
    HH(c, d, a, b, m[11], M33, 0x6d9d6122);   /* 35 */
    HH(b, c, d, a, m[14], M34, 0xfde5380c);   /* 36 */
    HH(a, b, c, d, m[1],  M31, 0xa4beea44);   /* 37 */
    HH(d, a, b, c, m[4],  M32, 0x4bdecfa9);   /* 38 */
    HH(c, d, a, b, m[7],  M33, 0xf6bb4b60);   /* 39 */
    HH(b, c, d, a, m[10], M34, 0xbebfbc70);   /* 40 */
    HH(a, b, c, d, m[13], M31, 0x289b7ec6);   /* 41 */
    HH(d, a, b, c, m[0],  M32, 0xeaa127fa);   /* 42 */
    HH(c, d, a, b, m[3],  M33, 0xd4ef3085);   /* 43 */
    HH(b, c, d, a, m[6],  M34, 0x4881d05);    /* 44 */
    HH(a, b, c, d, m[9],  M31, 0xd9d4d039);   /* 45 */
    HH(d, a, b, c, m[12], M32, 0xe6db99e5);   /* 46 */
    HH(c, d, a, b, m[15], M33, 0x1fa27cf8);   /* 47 */
    HH(b, c, d, a, m[2],  M34, 0xc4ac5665);   /* 48 */
    /* Round 4 */
    II(a, b, c, d, m[0],  M41, 0xf4292244);   /* 49 */
    II(d, a, b, c, m[7],  M42, 0x432aff97);   /* 50 */
    II(c, d, a, b, m[14], M43, 0xab9423a7);   /* 51 */
    II(b, c, d, a, m[5],  M44, 0xfc93a039);   /* 52 */
    II(a, b, c, d, m[12], M41, 0x655b59c3);   /* 53 */
    II(d, a, b, c, m[3],  M42, 0x8f0ccc92);   /* 54 */
    II(c, d, a, b, m[10], M43, 0xffeff47d);   /* 55 */
    II(b, c, d, a, m[1],  M44, 0x85845dd1);   /* 56 */
    II(a, b, c, d, m[8],  M41, 0x6fa87e4f);   /* 57 */
    II(d, a, b, c, m[15], M42, 0xfe2ce6e0);   /* 58 */
    II(c, d, a, b, m[6],  M43, 0xa3014314);   /* 59 */
    II(b, c, d, a, m[13], M44, 0x4e0811a1);   /* 60 */
    II(a, b, c, d, m[4],  M41, 0xf7537e82);   /* 61 */
    II(d, a, b, c, m[11], M42, 0xbd3af235);   /* 62 */
    II(c, d, a, b, m[2],  M43, 0x2ad7d2bb);   /* 63 */
    II(b, c, d, a, m[9],  M44, 0xeb86d391);   /* 64 */
    state[0] += a;
    state[1] += b;
    state[2] += c;
    state[3] += d;
}

inline void Init(Context * context) {
    context->count[0] = context->count[1] = 0;
    context->state[0] = 0x67452301;
    context->state[1] = 0xefcdab89;
    context->state[2] = 0x98badcfe;
    context->state[3] = 0x10325476;
}

inline void Update(Context * context, unsigned char * buf, int len) {
    unsigned int i, index, partLen;
    index = (unsigned int) ((context->count[0] >> 3) & 0x3F);
    if ((context->count[0] += ((unsigned int) len << 3)) < ((unsigned int) len << 3))
        context->count[1]++;
    context->count[1] += ((unsigned int) len >> 29);
    partLen = 64 - index;
    if (len >= partLen) {
        memcpy((char *) &context->buffer[index], (char *) buf, partLen);
        Transform(context->state, context->buffer);
        for (i = partLen; i + 63 < len; i += 64)
            Transform(context->state, &buf[i]);
        index = 0;
    } else {
        i = 0;
    }
    memcpy((char *) &context->buffer[index], (char *) &buf[i], len - i);
}

inline void Final(Context * context, unsigned char digest[16]) {
    unsigned char append[64] = { 0x80 };
    unsigned char length[8];
    unsigned int index, padLen;
    Encode(length, context->count, 8);
    index = (unsigned int) ((context->count[0] >> 3) & 0x3f);
    padLen = (index < 56) ? (56 - index) : (120 - index);
    Update(context, append, padLen);
    Update(context, length, 8);
    Encode(digest, context->state, 16);
}

inline void File (char * filename) {
    FILE *file;
    Context context;
    unsigned char buf[16];
    int i,len;
    unsigned char buffer[0x0400];
    if (!(file = fopen (filename, "rb"))) {
        printf ("%s can't be opened\n", filename);
    } else {
        Init (&context);
        while (len = fread (buffer, 1, 1024, file)) {
            Update (&context, buffer, len);
        }
        Final(&context,buf);
        fclose (file);
        printf("The answer is :\n");
        for(i=0;i<16;i++) {
            printf("%x",(buf[i] & 0xF0)>>4);
            printf("%x",buf[i] & 0x0F);
        }
        printf("\n");
    }
}

int main() {
    char filename[100];
    clock_t start,end;
    printf("MD5 code\n");
    while(1) {
        printf("\nPlease input filename: ( Exit with no filename )\n");
        gets(filename);
        if(!strlen(filename))   break;
        printf(".......... Start coding ..........\n");
        start=clock();
        File(filename);
        end=clock();
        printf(".......... End coding   ..........\n");
        printf("The time costs : %.3lf s\n",(double)difftime(end,start)/1000);
    }
    return 0;
}