Convert Declets To Binary Coded Decimal.
The low-order 20 bits of each word of the source contain two declets that are converted to six, 4-bit BCD fields; each set of six, 4-bit BCD fields is placed into the low-order 24 bits of the corresponding word in the result. The high-order 8 bits in each word of the result are set to 0.
long long __cdtbcd (long long);
Valid only when -qarch is set to target POWER7 processors.