Altera Floating-Point Uživatelský manuál Strana 61

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Port Name Required Description
overflow No Overflow port for the divider. Asserted when the result of the division
(after rounding) exceeds or reaches infinity. Infinity is defined as a
number in which the exponent exceeds 2WIDTH_EXP–1.
underflow No Underflow port for the divider. Asserted when the result of the
division (after rounding) is zero even though neither of the inputs to
the divider is zero, or when the result is a denormalized number.
zero No Zero port for the divider. Asserted when the value of result[] is
zero.
division_by_
zero
No Division-by-zero output port for the divider. Asserted when the value
of datab[] is a zero.
nan No NaN port. Asserted when an invalid division occurs, such as infinity
dividing infinity or zero dividing zero. A NaN value appears as
output at the result[] port. Any division of a NaN value causes the
nan output port to be asserted.
ALTFP_DIV Parameters
Table 6-7: ALTFP_DIV 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 single precision and 1023 for double
precision. The value of WIDTH_EXP must be 8 for single
precision, 11 for double precision, and a minimum of
11 for single extended precision.
The value of WIDTH_EXP must be less than the value of
WIDTH_MAN, and the sum of WIDTH_EXP and WIDTH_MAN
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. When
WIDTH_EXP is 8 and the floating-point format is the
single-precision format, the WIDTH_MAN value must be
23. Otherwise, the value of WIDTH_MAN must be a
minimum of 31.
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.
ROUNDING String Yes Specifies the rounding mode. The default value is TO_
NEAREST. The floating-point divider does not support
other rounding modes.
UG-01058
2014.12.19
ALTFP_DIV Parameters
6-7
ALTFP_DIV IP Core
Altera Corporation
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