Altera Floating-Point - Manual (Page 98)

Port Name Required Description
zero
No Zero exception output. Asserted when the exponent and mantissa
of the output port are zero. This occurs when the actual input value
is
1
because ln
1 = 0
.
nan
No NaN exception output. Asserted when the exponent and mantissa
of the output port are all 1’s and non-zero, respectively. This occurs
when the input is a negative number or NaN.
Parameters
Table 12-7: ALTFP_LOG Megafunction Parameters
Parameter Name Type Required Description
WIDTH_EXP Integer Yes Specifies the precision of the exponent. If this
parameter is not specified, the default is
8
. The bias
of the exponent is always set to
2 (WIDTH_EXP -1) -1
,
that is,
127
for the single-precision format and
1023
for the double-precision format. The value of the
WIDTH_EXP
parameter must be
8
for the single-
precision format,
11
for the double-precision
format, and a minimum of
11
for the single-
extended precision format. The value of the
WIDTH_
EXP
parameter must be less than the value of the
WIDTH_MAN
parameter, and the sum of the
WIDTH_
EXP
and
WIDTH_MAN
parameters must be less than
64
.
WIDTH_MAN Integer Yes Specifies the precision of the mantissa. If this
parameter is not specified, the default is
23
. The
value of
WIDTH_MAN
must be
23
for the single-
precision format, and
52
for the double-precision
format. For the single-extended precision format,
the valid value ranges from
31
to
52
. The value of
WIDTH_MAN
must be greater than the value of
WIDTH_
EXP
, and the sum of
WIDTH_EXP
and
WIDTH_MAN
must be less than
64
.
PIPELINE Integer Yes Specifies the amount of latency in clock cycles used
in the ALTFP_LOG megafunction. Create the
ALTFP_LOG megafunction with the MegaWizard
Plug-In Manager to calculate the value for this
parameter.
12-6 Parameters
UG-01058
2014.12.19
Altera Corporation ALTFP_LOG
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