The complex DOT instructions perform a dot-product on quadtuplets from
two source vectors and the resuling wide real or wide imaginary is
accumulated into the destination register. The instructions come in two
forms:
Vector form, e.g.
cdot z0.s, z1.b, z2.b, #90 - complex dot product on four 8-bit quad-tuplets, accumulating results in 32-bit elements. The complex numbers in the second source vector are rotated by 90 degrees. cdot z0.d, z1.h, z2.h, #180 - complex dot product on four 16-bit quad-tuplets, accumulating results in 64-bit elements. The complex numbers in the second source vector are rotated by 180 degrees.
Indexed form, e.g.
cdot z0.s, z1.b, z2.b[3], #0 - complex dot product on four 8-bit quad-tuplets, with specified quadtuplet from second source vector, accumulating results in 32-bit elements. cdot z0.d, z1.h, z2.h[1], #0 - complex dot product on four 16-bit quad-tuplets, with specified quadtuplet from second source vector, accumulating results in 64-bit elements.
The specification can be found here:
https://developer.arm.com/docs/ddi0602/latest