Floating-Point IP Cores User Guide

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ID 683750
Date 9/13/2021
Public
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3.7. ALTFP_ADD_SUB Parameters

Table 18.  ALTFP_ADD_SUB Parameters
Parameter Name Type Required Description
DIRECTION String Yes Specifies addition or subtraction operations. Values are ADD, SUB, or VARIABLE. If this parameter is not specified, the default is ADD. When the value is VARIABLE, the add_sub port determines whether the operation is addition or subtraction. The add_sub port must be connected if the DIRECTION parameter is set to VARIABLE. If the value is ADD or SUB, the add_sub port is ignored.
PIPELINE Integer No Specifies the latency in clock cycles used in the ALTFP_ADD_SUB IP core. The PIPELINE parameter supports values of 7 through 14. If this parameter is not specified, the default value is 11. In general, a higher pipeline value produces better fMAX performance.
ROUNDING String Yes Specifies the rounding mode. The default value is TO_NEAREST. Other rounding modes are currently not supported.
OPTIMIZE String No Defines the design preference, whether the design is optimized for speed (faster fMAX), or optimized for area (lower resource count). Values are SPEED and AREA. If this parameter is not specified, the default is SPEED.
WIDTH_EXP Integer No Specifies the precision of the exponent. The bias of the exponent is always set to 2 (WIDTH_EXP-1) -1 (that is, 127 for single-precision format and 1023 for double-precision format). The WIDTH_EXP parameter must be 8 for the single-precision mode and 11 for the double-precision mode, or a minimum of 11 for the single-extended precision mode. The WIDTH_EXP parameter must be less than the WIDTH_MAN parameter. The sum of WIDTH_EXP and the WIDTH_MAN parameters must be less than 64. If this parameter is not specified, the default is 8.
WIDTH_MAN Integer No Specifies the precision of the mantissa. The WIDTH_MAN parameter must be 23 (to comply with the IEEE-754 standard for the single-precision mode) when the WIDTH_EXP parameter is 8. Otherwise, the WIDTH_MAN parameter must have a value that is greater than or equal to 31. The WIDTH_MAN parameter must be greater than the WIDTH_EXP parameter. The sum of the WIDTH_EXP and WIDTH_MAN parameters must be less than 64. If this parameter is not specified, the default is 23.

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