Altera Floating-Point - Manual (Page 107)

In this example, the latency of the multiplier is set to five clock cycles, while none is being set for the
absolute value function. Thus, the absolute value result only appears at the
result[]
port five cycles after
the input values are captured on the input ports.
The
dataa[]
and
datab[]
values in the simulation waveform above portray the two input values that are
being fed to the multiplier. The value in the
result[]
port depicts the multiplication result that has gone
through the absolute value operation.
This table lists the inputs and corresponding outputs obtained from the simulation.
Table 15-2: Summary of Input Values and Corresponding Outputs
Time Event
0 ns, start-up
dataa[]
value: C080 0000h
datab[]
value: 4000 0000h
Output value: All values seen on the output port before the 5th clock cycle are
merely due to the behavior of the system during start-up and should be
disregarded.
22.5 ns Output value: 4100 0000h
The multiplication of a negative number with a positive number results in a
negative number. The absolute value of the result is reflected on the
result[]
port.
20 ns
dataa[]
value: 579D F479h
datab[]
value: 7F80 0000h
The value of
dataa[]
is normal while the value of
datab[]
is infinity.
42.5 ns Output value: 7F80 0000h
Exception handling ports:
overflow
asserts
The multiplication of a normal value with infinity results in infinity and sets
the
overflow
port in the multiplier. The absolute value of the output is infinity
and the
overflow
port is also set as this assertion of the port is being carried
through from the corresponding
overflow
port in the multiplier.
ALTFP_ABS Signals
UG-01058
2014.12.19
ALTFP_ABS Signals 15-3
ALTFP_ABS IP Core Altera Corporation
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