Floating-Point IP Cores User Guide

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ID 683750
Date 9/13/2021
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4.7. ALTFP_DIV Parameters

Table 25.  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.
OPTIMIZE String No Specifies whether to optimize for area or for speed. Values are AREA and SPEED. A value of AREA optimizes the design using less total logic utilization or resources. A value of SPEED optimizes the design for better performance. If this parameter is not specified, the default value is SPEED.
PIPELINE Integer No Specifies the number of clock cycles needed to produce the result. For the single-precision format, the latency options are 33, 14 or 6. For the double-precision format, the latency options are 61, 24 or 10.

For the single-extended precision format, the value ranges from a minimum of 41 to a maximum of 61. For the low-latency option, the latency is determined from the mantissa width. For a mantissa width of 31 to 40 bits, the value is 8 or 18. For a mantissa width of 41 bits or more, the value is 10 or 24.

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