Visible to Intel only — GUID: eis1411614823037
Ixiasoft
Visible to Intel only — GUID: eis1411614823037
Ixiasoft
8.5.1. ALTFP_INV Design Example: Understanding the Simulation Results
These figures show the expected simulation results in the ModelSim* - Intel® FPGA Edition software.
This design example implements a floating-point inverse for single-precision format numbers. The optional input ports (clk_en and aclr) and all four exception handling output ports (division_by_zero, nan, zero, and underflow) are enabled.
The latency is fixed at 20 clock cycles; therefore, every inverse operation outputs results 20 clock cycles later.
This table lists the inputs and corresponding outputs obtained from the simulation in the waveforms.
Time | Event |
---|---|
0 ns, start-up | data[] value: 34A2 E42Fh Output value: An undefined value is seen on the result[] port, which is ignored. All values seen on the output port before the 20th clock cycle are merely due to the behavior of the system during start-up and should be disregarded. |
97.5 ns | Output value: 4A49 2A2Fh Exception handling ports: division_by_zero deasserts The inverse of a normal number results in a normal value. |
10 ns | data[] value: 7F80 0000h This is an infinity value. |
107.5 ns | Output value: 0000 0000h Exception handling ports: zero asserts The inverse of an infinity value produces a zero. |
60 ns | data[] value: 7FC0 0000h This is a NaN. |
157.5 ns | Output value: 7FC0 0000h Exception handling ports: nan asserts The inverse of a NaN results in a NaN |
70 ns | data[] value: 0000 1000h This is a denormal number. |
167.5 ns | Output value: 7F80 0000h Exception handling ports: nan deasserts, division_by_zero asserts Denormal numbers are forced-zero values, therefore, the inverse of a zero results in infinity. |