This document describes the structure and execution of the dynamic evaluation module, implemented as a dynamicEval function.
The structure of dynamicEval is described as below. The primitive has 4-stream and 4-constant as inputs. The data type of the input stream and constant is a template parameter in the API, and the maximum width of the constant is limited to 64-bits.
The primitive is a tree-shaped structure with evaluation cells in each node. Each evaluation cell provides four kinds of computing units, which are: compare, boolean algebra, multiplex, and math compute. For comparator and boolean algebra, the results are in boolean type, while multiplex and math compute will generate non-boolean results. The internal of dynamic eval will expread two types of results from one cell to the next level of cells. There are two types of cell design. For Cell1-Cell4, as the level-1 cells, the two inputs which are stream and constant, respectively. For Cell5-Cell7, as the internal cells, which need to process both boolean and non-boolean results from the previous level. Cell1-Cell4 is shown as:
While Cell5-Cell7 has more inputs to select:
The configuration of the primitive is defined as follows, and the bits are concatenated without padding from top to bottom in least significant bit (LSB) to most significant bit (MSB) order.
| Type | Usage | Size |
|---|---|---|
| Operator | Output Mux | 1 bit |
| Strm Empty | 4 bit | |
| Cell1 OP | 4 bit | |
| Cell2 OP | 4 bit | |
| Cell3 OP | 4 bit | |
| Cell4 OP | 4 bit | |
| Cell5 OP | 4 bit | |
| Cell6 OP | 4 bit | |
| Cell7 OP | 4 bit | |
| Operand | C1 | 64 bit |
| C2 | 64 bit | |
| C3 | 64 bit | |
| C4 | 64 bit |
To automatically generate its configuration, refer to the test case in L3/tests/sw/dynamic_alu_host/test.cpp.
To manually generate configuration, refer to the built-in docs in L1/include/hw/xf_database/dynamic_eval.hpp.