NANOSCALE STANDARD DIGITAL MODULES - Bio-Inspired and Nanoscale Integrated Computing - page 257

TABLE 9 . 11 . Frequency Assignments in the First Method of
p-shifter Implementation
Node Sending frequency Receiving frequency

Binary p inputs f adc -

Input nodes Variable (f i ) f adc

Output node i - f i

the input nodes receive the analog value of p. Each input node knows its own
index i and has received the value p. Depending on the shift direction d, each input
node finds the index of the output node to which its data should be sent. If the
shifter is in ''shift to the right'' status, each node x i should send its data to the
output node with index i p; if it is in ''shift to the left'' status, the data is sent to
the node with index i+p. Therefore node x i sends its data on frequency f i p if d
indicates shift to the right and on f i+p for shift to the left. Table 9.11 shows the
frequency assignments for implementing a spin-wave p-shifter.
Note that in order to use the same nodes as both input and output similar to a
simple shifter, the shifting operation will have two main steps. In the first step, all
the nodes' receiving frequency is tuned on a common frequency f adc so that all
receive the analog value of p. In the second step, the nodes' receiving frequencies
are dynamically tuned on distinct frequencies to receive the data as explained in
the previous method. Table 9.12 shows the frequency assignments for implement-
ing a spin-wave p-shifter. This structure is shown in Figure 9.12.

9.4.2. Nanoscale Spin-Wave Priority Encoder
A priority encoder is used to select, according to a predefined priority, one of the
several events that can occur simultaneously; the selected event is represented by
an integer [1]. In this section we first explain the design of a standard priority
encoder with fixed priority order, and afterwards, the implementation of a
programmable priority encoder.

S PIN - WAVE P RIORITY E NCODER . A standard priority encoder has N-bit inputs
and k-bit outputs, where N=2 k . Unlike the binary encoder that can have one

TABLE 9 . 12 . Frequency Assignments in the Second Method of
p-shifter Implementation
Node

Sending
frequency

Receiving
frequency

Binary p inputs f adc -

Input/output nodes (step 1) Variable (f i ) f adc

Input/output node i (step 2) - f i