| 摘要 |
A pipelined interpolator precomputes both integer and fractional portions of the slope of the function to be interpolated. The fractional portions of the starting value of the dependent variable to be incremented and the fractional value of the slope by which the increment occurs are each scaled to allow integer arithmetic. The scaled fractional portion of the starting value of the dependent variable is offset by a constant to allow carry-outs to be detected with the comparison "greater than or equal to zero." The occurrence of a carry-out causes the (unscaled) integer portion of the dependent variable to be incremented by the (unscaled) integer portion of the slope. A selected one of two pairs of simultaneous integer additions on the sets of the integer portion and the scaled fractional portion of the dependent variable will be performed. One pair is selected when the carry-out from the scaled fractional portion did not occur. The other pair is selected when it did. The values produced by the selected pair of additions are fed to the next stage in the pipeline and allowed to actually update the dependent variable's integer and scaled fractional portions.
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