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// If we have 64-bit ints, pick off 6 bytes at a time for as long as we can,
// but ensure that there are at least 8 bytes available to avoid segfaulting:
while (srclen >= 8)
{
// Load string:
//uint64_t str = *(uint64_t *)c;
uint64_t str;
memcpy(&str, c, sizeof(str));
// Reorder to 64-bit big-endian, if not already in that format. The
// workset must be in big-endian, otherwise the shifted bits do not
// carry over properly among adjacent bytes:
str = cpu_to_be64(str);
// Shift input by 6 bytes each round and mask in only the lower 6 bits;
// look up the character in the Base64 encoding table and write it to
// the output location:
*o++ = plain64_base64_table_enc[(str >> 58) & 0x3F];
*o++ = plain64_base64_table_enc[(str >> 52) & 0x3F];
*o++ = plain64_base64_table_enc[(str >> 46) & 0x3F];
*o++ = plain64_base64_table_enc[(str >> 40) & 0x3F];
*o++ = plain64_base64_table_enc[(str >> 34) & 0x3F];
*o++ = plain64_base64_table_enc[(str >> 28) & 0x3F];
*o++ = plain64_base64_table_enc[(str >> 22) & 0x3F];
*o++ = plain64_base64_table_enc[(str >> 16) & 0x3F];
c += 6; // 6 bytes of input
outl += 8; // 8 bytes of output
srclen -= 6;
}
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