A.5.223 PFRSQIT1: Packed Single-Precision FP Reciprocal Square Root, First
Iteration Step
PFRSQIT1 mm1,mm2/m64 ; 0F 0F /r A7 [PENT,3DNOW]
PFRSQIT1 performs the first intermediate step in the calculation of the
reciprocal square root of a single-precision FP value. The first source
value ("mm1" is the square of the result of a PFRSQRT instruction, and
the second source value ("mm2/m64" is the original value.
For the final step in a calculation, returning the full 24-bit accuracy
of a single-precision FP value, see PFRCPIT2 (section A.5.222). For more
details, see the AMD 3DNow! technology manual.