Browsing by Author "Şahin, Hatice"

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    MLUE : Multiple look-up table based exponentiation
    (Bahçeşehir Üniversitesi Fen Bilimleri Enstitüsü, 2011-09) Şahin, Hatice; Uğurdağ, H. Fatih
    Many scientific applications require computation of exponents. In this thesis, we are specifically interested in computing a constant to the power of a variable number (ax), which can always be converted to 2x through an extra multiplication without loss of generality. In real-time systems or any application where run-time matters, ax is computed using a Look-Up Table (LUT). However, when the targeted precision is high, the table size blows up. Piecewise Polynomial Approximation (PPA) offers a tradeoff between speed and table size and is commonly used in the literature. Our contribution in this thesis is an alternative method, which can also offer a trade-off between speed and table size. It is called MLUE (short for Multiple Look-Up table based Exponentiation). MLUE partitions the input bits into segments. There is a LUT for each segment, and the result is the product of LUT outputs. While PPAs contain both method error and truncation error, MLUE has only truncation error. Although MLUE can be utilized in software implementations, we have looked at its performance when implemented in hardware – and specifically with combinational logic. Our claim is that MLUE offers smaller area for a reasonable target speed and precision. We wrote fully automated and parameterized design (RTL level Verilog) generators for both PPA and MLUE. We back up our claim through numerous results obtained with an automated regression script, which calls our generators. The contributions of this thesis also include regression methodology/scripts, a novel logic synthesis strategy/script, fully automated testing of the generated designs as well as automatic determination polynomial degree in PPA and number of MLUE bit partitions.