Efficient rounding circuits and methods in configurable integrated circuit devices
First Claim
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1. A specialized processing block for a configurable integrated circuit device, said specialized processing block comprising:
- arithmetic circuitry that provides a result based on arithmetic functions of inputs;
accumulator circuitry including an adder to which said result is applied as a first input; and
rounding circuitry including said adder and a selector that selectably applies as a second input to said adder one of (a) output of said adder, whereby said adder functions as an accumulator, and (b) a rounding constant, whereby output of said adder, truncated to a selected bit position, is a rounded version of said result.
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Abstract
A specialized processing block for a configurable integrated circuit device includes circuitry for performing multiplications and sums thereof, as well as circuitry for rounding the result. The rounding circuitry reuses an adder that is also available, in other configurations, for accumulation of the result. Rounding is performed by adding a constant to the result and then truncating at the bit position at which rounding is desired. The constant may be entered by a user, or may be derived based on a desired rounding method from mask data entered by the user to identify the rounding bit position.
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Citations
24 Claims
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1. A specialized processing block for a configurable integrated circuit device, said specialized processing block comprising:
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arithmetic circuitry that provides a result based on arithmetic functions of inputs; accumulator circuitry including an adder to which said result is applied as a first input; and rounding circuitry including said adder and a selector that selectably applies as a second input to said adder one of (a) output of said adder, whereby said adder functions as an accumulator, and (b) a rounding constant, whereby output of said adder, truncated to a selected bit position, is a rounded version of said result. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of configuring a configurable integrated circuit device that includes a specialized processing block having arithmetic circuitry that provides a result based on arithmetic functions of inputs, accumulator circuitry including an adder to which said result is applied as a first input, and a selector that selectably applies as a second input to said adder one of (a) output of said adder, and (b) a rounding constant, said method comprising:
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configuring said selector to apply said rounding constant as said second input of said adder;
whereby;output of said adder, truncated to a selected bit position, is a rounded version of said result. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A machine-readable data storage medium encoded with machine-executable instructions for configuring a configurable device, that includes a specialized processing block having arithmetic circuitry that provides a result based on arithmetic functions of inputs, accumulator circuitry including an adder to which said result is applied as a first input, and a selector that selectably applies as a second input to said adder one of (a) output of said adder, and (b) a rounding constant, to round said result, said instructions comprising:
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instructions to configure said selector to apply said rounding constant as said second input of said adder;
whereby;output of said adder, truncated to a selected bit position, is a rounded version of said result. - View Dependent Claims (20, 21, 22, 23, 24)
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Specification