On 2015-03-11, at 08:49, John McKown wrote: > And POPCNT is another > one. Why do I need to know the number of 1 bits in each individual > byte in a GPR? > Because CDC had it first? I suspect that it became a built-in function in Pascal, CARD(), because Pascal was developed on a CDC which had the hardware. And I suspect FORTRAN's transfer- of-sign, SIGNF() happened because it was a hardware instruction on the 704.
Is POPCNT an inexpensive extension of the Wallace Tree? -- gil
