Function _mm_extract_si64

Extracts the bit range specified by y from the lower 64 bits of x.

The [13:8] bits of y specify the index of the bit-range to extract. The [5:0] bits of y specify the length of the bit-range to extract. All other bits are ignored.

If the length is zero, it is interpreted as 64. If the length and index are zero, the lower 64 bits of x are extracted.

If length == 0 && index > 0 or length + index > 64 the result is undefined.

The extracted bits are saved in the least-significant bit positions of the lower quadword of the destination; the remaining bits in the lower quadword of the destination register are cleared to 0. The upper quadword of the destination register is undefined.