在做IAP升級過程中，bin文件有時大於接收的ram空間，而又需要進行MD5計算，這個時候就需要把bin文件拆分一段一段的計算，以下程序已經經過STM32的驗證，可以直接使用。
#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 RL(x, y) (((x) << (y)) | ((x) >> (32 - (y))))
#define FF(a, b, c, d, x, s, ac) a = b + (RL((a + F(b, c, d) + x + ac), s))
#define GG(a, b, c, d, x, s, ac) a = b + (RL((a + G(b, c, d) + x + ac), s))
#define HH(a, b, c, d, x, s, ac) a = b + (RL((a + H(b, c, d) + x + ac), s))
#define II(a, b, c, d, x, s, ac) a = b + (RL((a + I(b, c, d) + x + ac), s))
#define PP(x) (x << 24) | ((x << 8) & 0xff0000) | ((x >> 8) & 0xff00) | (x >> 24)
uint32_t ulFlashAdd = 0, ulFlieLength = 0;
uint8_t ucaFlashBuf[1025];
uint32_t A = 0x67452301, B = 0xefcdab89, C = 0x98badcfe, D = 0x10325476, a, b, c, d, x[16];
void MD5(void)
{
a = A, b = B, c = C, d = D;
FF(a, b, c, d, x[0], 7, 0xd76aa478);
FF(d, a, b, c, x[1], 12, 0xe8c7b756);
FF(c, d, a, b, x[2], 17, 0x242070db);
FF(b, c, d, a, x[3], 22, 0xc1bdceee);
FF(a, b, c, d, x[4], 7, 0xf57c0faf);
FF(d, a, b, c, x[5], 12, 0x4787c62a);
FF(c, d, a, b, x[6], 17, 0xa8304613);
FF(b, c, d, a, x[7], 22, 0xfd469501);
FF(a, b, c, d, x[8], 7, 0x698098d8);
FF(d, a, b, c, x[9], 12, 0x8b44f7af);
FF(c, d, a, b, x[10], 17, 0xffff5bb1);
FF(b, c, d, a, x[11], 22, 0x895cd7be);
FF(a, b, c, d, x[12], 7, 0x6b901122);
FF(d, a, b, c, x[13], 12, 0xfd987193);
FF(c, d, a, b, x[14], 17, 0xa679438e);
FF(b, c, d, a, x[15], 22, 0x49b40821);
GG(a, b, c, d, x[1], 5, 0xf61e2562);
GG(d, a, b, c, x[6], 9, 0xc040b340);
GG(c, d, a, b, x[11], 14, 0x265e5a51);
GG(b, c, d, a, x[0], 20, 0xe9b6c7aa);
GG(a, b, c, d, x[5], 5, 0xd62f105d);
GG(d, a, b, c, x[10], 9, 0x02441453);
GG(c, d, a, b, x[15], 14, 0xd8a1e681);
GG(b, c, d, a, x[4], 20, 0xe7d3fbc8);
GG(a, b, c, d, x[9], 5, 0x21e1cde6);
GG(d, a, b, c, x[14], 9, 0xc33707d6);
GG(c, d, a, b, x[3], 14, 0xf4d50d87);
GG(b, c, d, a, x[8], 20, 0x455a14ed);
GG(a, b, c, d, x[13], 5, 0xa9e3e905);
GG(d, a, b, c, x[2], 9, 0xfcefa3f8);
GG(c, d, a, b, x[7], 14, 0x676f02d9);
GG(b, c, d, a, x[12], 20, 0x8d2a4c8a);
HH(a, b, c, d, x[5], 4, 0xfffa3942);
HH(d, a, b, c, x[8], 11, 0x8771f681);
HH(c, d, a, b, x[11], 16, 0x6d9d6122);
HH(b, c, d, a, x[14], 23, 0xfde5380c);
HH(a, b, c, d, x[1], 4, 0xa4beea44);
HH(d, a, b, c, x[4], 11, 0x4bdecfa9);
HH(c, d, a, b, x[7], 16, 0xf6bb4b60);
HH(b, c, d, a, x[10], 23, 0xbebfbc70);
HH(a, b, c, d, x[13], 4, 0x289b7ec6);
HH(d, a, b, c, x[0], 11, 0xeaa127fa);
HH(c, d, a, b, x[3], 16, 0xd4ef3085);
HH(b, c, d, a, x[6], 23, 0x04881d05);
HH(a, b, c, d, x[9], 4, 0xd9d4d039);
HH(d, a, b, c, x[12], 11, 0xe6db99e5);
HH(c, d, a, b, x[15], 16, 0x1fa27cf8);
HH(b, c, d, a, x[2], 23, 0xc4ac5665);
II(a, b, c, d, x[0], 6, 0xf4292244);
II(d, a, b, c, x[7], 10, 0x432aff97);
II(c, d, a, b, x[14], 15, 0xab9423a7);
II(b, c, d, a, x[5], 21, 0xfc93a039);
II(a, b, c, d, x[12], 6, 0x655b59c3);
II(d, a, b, c, x[3], 10, 0x8f0ccc92);
II(c, d, a, b, x[10], 15, 0xffeff47d);
II(b, c, d, a, x[1], 21, 0x85845dd1);
II(a, b, c, d, x[8], 6, 0x6fa87e4f);
II(d, a, b, c, x[15], 10, 0xfe2ce6e0);
II(c, d, a, b, x[6], 15, 0xa3014314);
II(b, c, d, a, x[13], 21, 0x4e0811a1);
II(a, b, c, d, x[4], 6, 0xf7537e82);
II(d, a, b, c, x[11], 10, 0xbd3af235);
II(c, d, a, b, x[2], 15, 0x2ad7d2bb);
II(b, c, d, a, x[9], 21, 0xeb86d391);
A += a;
B += b;
C += c;
D += d;
}
uint32_t ulSampleIndex = 0;
uint32_t ulDataIndex = 0;
uint32_t ulReadCnt = 0;
void ReadGroupTempBuf(void)
{
uint8_t j, k;
memset(x, 0, 64);
ulSampleIndex = 0;
for (j = 0; j < 16; j++)
{
for (k = 0; k < 4; k++)
{
if ((ulReadCnt >= ulFlieLength / 1024) && (ulDataIndex >= ulFlieLength % 1024))
break;
((char *)x)[ulSampleIndex] = ucaFlashBuf[ulDataIndex];
ulDataIndex++;
ulSampleIndex++;
}
}
}
void GetBinFileMd5(char *pEsult)
{
uint16_t usCnt = 0;
uint32_t ulFileLen[2] = {0};
/* 計算整數部分 */
for (ulReadCnt = 0; ulReadCnt < ulFlieLength / 1024; ulReadCnt++)
{
GetWifiFlashDataWait(ulFlashAdd, ucaFlashBuf, 1024);
ulFlashAdd += 1024;
for (usCnt = 0; usCnt < 16; usCnt++)
{
ReadGroupTempBuf();
MD5();
}
ulDataIndex = 0;
}
/* 計算餘數部分 */
memset(ucaFlashBuf, 0, 1025);
GetWifiFlashDataWait(ulFlashAdd, ucaFlashBuf, ulFlieLength % 1024);
ReadGroupTempBuf();
for (usCnt = 0; usCnt < (ulFlieLength % 1024) / 64; usCnt++)
{
MD5();
ReadGroupTempBuf();
}
/* 文件結束補1,補0操作,128二進制即10000000 */
((char *)x)[ulFlieLength % 64] = 128;
if (ulFlieLength % 64 > 55)
{
MD5(), memset(x, 0, 64);
}
/* 文件末尾加入原文件的bit長度 */
ulFileLen[1] = ulFlieLength / 0x20000000;
ulFileLen[0] = (ulFlieLength % 0x20000000) * 8;
memcpy(x + 14, ulFileLen, 8);
MD5();
sprintf(pEsult, "%08X%08X%08X%08X", PP(A), PP(B), PP(C), PP(D));
}
使用方法，GetWifiFlashDataWait這個函數是從FLASH芯片讀取數據，參數1是地址，參數2是讀取數組，參數3讀取長度，這個函數根據自己實際情況去實現。兩個全局參數ulFlashAdd = 0, ulFlieLength = 0;ulFlashAdd是讀取bin文件的基地址，ulFlieLength是整個bin文件的長度，最後調用GetBinFileMd5函數，從形參讀取返回計算結果即可。