Altera Floating-Point - Manual (Page 45)

Port Name Required Description
xo
Yes The overflow flag for port
x
. The signal goes high when the exponent of
the input
x
is larger than maxMSBX. The signal remains high for the
entire data set. This flag invalidates port
r
. You should consider
increasing maxMSBX. This flag also indicate infinity and NaN.
xu
Yes The underflow flag for port
x
. The signal goes high when the exponent
of the input
x
is smaller than LSBA. The signal remains high for the
entire data set. This flag does not invalidate port
r
. You should consider
lowering LSBA.
ao
Yes The overflow flag for Accumulator. The signal goes high when the
exponent of the accumulated value is larger than MSBA. The signal
remains high for the entire data set. This flag invalidates port
r
. You
should consider increasing MSBA.
ALTERA_FP_ACC_CUSTOM Parameters
Table 4-4: ALTERA_FP_ACC_CUSTOM Parameters
Category Parameter Values Description
Input Data
Floating point
format
single,
double
Choose the floating point format of the input
data values. The output data values of the
accumulator is in the same format.
The default is single.
maxMSBX — The maximum weight of the MSB of an input.
For example, when adding probabilities in the 0
to 1 range set this weight to ceil(log
2
(1))=0. The
xo
output signal goes high when the MSB of an
input value has a weight larger than maxMSBX.
The result of the accumulation is then invalid. If
you are unsure about the range of the inputs,
then set the maxMSBX parameter to MSBA, at
the possible expense of increased resource
usage.
The default value is 12.
4-4 ALTERA_FP_ACC_CUSTOM Parameters
UG-01058
2014.12.19
Altera Corporation ALTERA_FP_ACC_CUSTOM IP Core
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