Page 252 - DSP Integrated Circuits

6.4 SFGs in Precedence Form 237

In step four, all initial nodes are identified, i.e., x(ri), VI(TI\ and v^ri). These
nodes are assigned to node set NI, as shown in Figure 6.24.
In step five we remove all executable operations, i.e., all operations that have
only initial nodes as inputs. In this case we remove the five multiplications by the
coefficients: CQ, a\, 02, &i, and 62- The resulting graph is shown in Figure 6.18.

Figure 6.18 The operations CQ, b\, b%, a\, and a% have been removed

Repeating steps 4 and 5 we successively get the graphs shown in Figures 6.19
through 6.23. The sets of nodes shown in Figure 6.24 illustrate the order in which
the nodes must be computed.

Figure 6.19 Two additions have been removed

Figure 6.20 One addition has been removed

Figure 6.21 The quantization Figure 6.22 One multiplication
has been has been
removed removed