reduce

Performs reduction operations on Queue data like calculating a sum of all Queue elements, or like calculating XOR checksum.

reduce(din: Queue, init, *, f) → init

Calculates a reduction of an input Queue, using the binary operation f and the initial value init. The output data type, as well as the internal register, are the same as the type of the init input.

The example shows how to calculate XOR checksum of the input Queue. The input init has been fixed to 0, but has also been given a data type Uint[8](0) to make sure that internal register width and output value is also Uint[8]

drv(t=Queue[Uint[8]], seq=[[0xff, 0xff, 0xff, 0xff]]) \
    | reduce(init=Uint[8](0), f=lambda x, y: x ^ y) \
    | check(ref=[0])

Next example shows how to pack bits received as a Queue into a parallel data of the type Uint. It also shows that init input can be supplied at run time.

(drv(t=Queue[Uint[8]], seq=[[0, 1, 0, 1, 0, 1, 0]]),
 drv(t=Uint[8], seq=[1])) \
    | reduce(f=lambda x, y: (x << 1) | y) \
    | check(ref=[0xaa])

accum(din: Queue[Integer], init: Integer) → init

The accum() gear is a convenience gear for calculating the sum of all elements of the input Queue. It relies on the reduce() gear underneath:

@gear
def accum(din: Queue[Integer], init: Integer) -> b'init':
    return reduce(din, init, f=lambda x, y: x + y)

drv(t=Queue[Uint[4]], seq=[[0, 1, 2, 3, 4]]) \
    | accum(init=Uint[8](0)) \
    | check(ref=[10])