Calculation of trigonometric functions in an integrated circuit device
First Claim
1. Circuitry for computing on x and y datapaths a trigonometric function of an input on a z datapath, said circuitry comprising:
- a comparison element to determine that said input is at or above a threshold, or below said threshold;
a first left-shifter for shifting said z datapath by a constant when said input is below said threshold;
a second left-shifter for shifting an initialization value of said x datapath when said input is below said threshold;
a look-up table including inverse tangent values based on negative powers of 2, and based on negative powers of 2-plus-said-constant and shifted by said constant, for adding to/subtracting from said z datapath; and
shifters for right-shifting elements of said x and y datapaths by amounts incorporating said constant and respective predetermined shift amounts that are adjusted when said input is below said threshold.
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Accused Products
Abstract
Circuitry for computing on x and y datapaths a trigonometric function of an input on a z datapath includes a comparison element to determine that the input is at or above a threshold, or below the threshold. The circuitry also includes a first left-shifter for shifting the z datapath by a constant when the input is below the threshold, and a second left-shifter for shifting an initialization value of the x datapath when the input is below the threshold. The circuitry further includes a look-up table including inverse tangent values based on negative powers of 2, and based on negative powers of 2-plus-the-constant and shifted by the constant, for adding to/subtracting from the z datapath, shifters for right-shifting elements of the x and y datapaths by amounts incorporating the constant and respective predetermined shift amounts that are adjusted when the input is below the threshold.
336 Citations
40 Claims
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1. Circuitry for computing on x and y datapaths a trigonometric function of an input on a z datapath, said circuitry comprising:
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a comparison element to determine that said input is at or above a threshold, or below said threshold; a first left-shifter for shifting said z datapath by a constant when said input is below said threshold; a second left-shifter for shifting an initialization value of said x datapath when said input is below said threshold; a look-up table including inverse tangent values based on negative powers of 2, and based on negative powers of 2-plus-said-constant and shifted by said constant, for adding to/subtracting from said z datapath; and shifters for right-shifting elements of said x and y datapaths by amounts incorporating said constant and respective predetermined shift amounts that are adjusted when said input is below said threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of configuring a programmable integrated circuit device as circuitry for computing on x and y datapaths a trigonometric function of an input on a z datapath, said method comprising:
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configuring logic of said programmable integrated circuit device as a comparison element to determine that said input is at or above a threshold, or below said threshold; configuring logic of said programmable integrated circuit device as a first left-shifter for shifting said z datapath by a constant when said input is below said threshold; configuring logic of said programmable integrated circuit device as a second left-shifter for shifting an initialization value of said x datapath when said input is below said threshold; configuring memory of said programmable integrated circuit device as a look-up table including inverse tangent values based on negative powers of 2, and based on negative powers of 2-plus-said-constant and shifted by said constant, for adding to/subtracting from said z datapath; and configuring logic of said programmable integrated circuit device as shifters for right-shifting elements of said x and y datapaths by amounts incorporating said constant and respective predetermined shift amounts that are adjusted when said input is below said threshold. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A non-transitory machine-readable data storage medium encoded with machine-executable instructions for configuring a programmable integrated circuit device as circuitry for computing on x and y datapaths a trigonometric function of an input on a z datapath, said instructions comprising:
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instructions to configure logic of said programmable integrated circuit device as a comparison element to determine that said input is at or above a threshold, or below said threshold; instructions to configure logic of said programmable integrated circuit device as a first left-shifter for shifting said z datapath by a constant when said input is below said threshold; instructions to configure logic of said programmable integrated circuit device as a second left-shifter for shifting an initialization value of said x datapath when said input is below said threshold; instructions to configure memory of said programmable integrated circuit device as a look-up table including inverse tangent values based on negative powers of 2, and based on negative powers of 2-plus-said-constant and shifted by said constant, for adding to/subtracting from said z datapath; and instructions to configure logic of said programmable integrated circuit device as shifters for right-shifting elements of said x and y datapaths by amounts incorporating said constant and respective predetermined shift amounts that are adjusted when said input is below said threshold. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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Specification