Audiovox P965 Arkusz Danych Pobierz pdf (Strona 226)

API in C

223

int readLen(int fdSock)

{

char cFirstChar; // first character read from socket

char *cLength; // length of next message to read...will be cast to int at the end

int *iLen; // calculated length of next message (Cast to int)

cLength = calloc(sizeof(int), 1);

DEBUG ? printf("start readLen()\n") : 0;

read(fdSock, &cFirstChar, 1);

DEBUG ? printf("byte1 = %#x\n", cFirstChar) : 0;

// read 4 bytes

// this code SHOULD work, but is untested...

if ((cFirstChar & 0xE0) == 0xE0)

{

DEBUG ? printf("4-byte encoded length\n") : 0;

if (iLittleEndian)

{

cLength[3] = cFirstChar;

cLength[3] &= 0x1f; // mask out the 1st 3 bits

read(fdSock, &cLength[2], 1);

read(fdSock, &cLength[1], 1);

read(fdSock, &cLength[0], 1);

}

else

{

cLength[0] = cFirstChar;

cLength[0] &= 0x1f; // mask out the 1st 3 bits

read(fdSock, &cLength[1], 1);

read(fdSock, &cLength[2], 1);

read(fdSock, &cLength[3], 1);

}

iLen = (int *)cLength;

}

// read 3 bytes

else if ((cFirstChar & 0xC0) == 0xC0)

{

DEBUG ? printf("3-byte encoded length\n") : 0;

if (iLittleEndian)

{

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Audiovox P965 Arkusz Danych Strona 226