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SIGN detection and signed integer comparison for three-moduli SET {2n ±1, 2n+k}

Torabi Zeinab, Timarchi Somayeh

Computer Science

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2021

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T. 22 (3)

387–401

EN

Comparison, division, and sign detection are considered to be complicated op erations in a residue number system (RNS). A straightforward solution is to convert RNS numbers into binary formats and then perform complicated op erations using conventional binary operators. If efficient circuits are provided for comparison, division, and sign detection, the application of RNS can be extended to those cases that include these operations. For RNS comparison in three-moduli set τ = {2 n−1, 2 n+k , 2 n+1},(0 ≤ k ≤ n), we have found only one hardware realization. In this paper, an efficient RNS comparator is proposed for moduli set τ , which employs a sign-detection method and operates more efficiently than its counterparts. The proposed sign detector and comparator utilize dynamic range partitioning (DRP), which has been recently presented for unsigned RNS comparison. The delay and cost of the proposed comparator are lower than the previous works, which makes it appropriate for RNS applications with limited delay and cost.

2

Multifunctional unit for reverse conversion and sign detection based on five-moduli set { 2 2n , 2 n + 1, 2 n − 1, 2 n + 3, 2 n − 3 }

Mojahed Mohsen, Molahosseini Amir Sabbagh, Zarandi Azadeh Alsadat Emrani

Computer Science

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2021

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T. 22 (1)

101-121

EN

A high dynamic range moduli set { 2 2n , 2 n + 1, 2 n − 1, 2 n + 3, 2 n − 3} has recently been introduced as an arithmetically balanced five-modull set for the residue number system (RNS). In order to utilize this moduli set in applications handling signed numbers, two important components are needed: a sign detector, and a signed reverse converter. However, having both of these components results in high-hardware requirements, which makes RNS impractical. This paper overcomes this problem by designing a unified unit that can perform both signed reverse conversion as well as sign detection through the reuse of hardware. To the authors’ knowledge, this is the first attempt to design a sign detector for a moduli set that includes a {2 n 3} moduli. In order to achieve a hardwareamenable design, we first improved the performance of the previous unsigned reverse converter for this moduli set. Then, we extracted a sign-detection method from the structure of the reverse converter. Finally, we made an unsigned reverse converter-to-sign converter through the use of the extracted sign signal from the reverse converter. The experimental results show that the proposed reverse convertor and sign detector result in improvements of 31% and 28% in area and delay, respectively, as compared to the previous unsigned reverse convertor with sign output using a comparator.

3

Zmodyfikowane mnożenie o stałej szerokości bitowej

Jamro E., Wielgosz M., Russek P., Wiatr K.

Pomiary Automatyka Kontrola

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2010

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R. 56, nr 10

1133-1136

PL

Niniejszy artykuł prezentuje nową metodę kompensacji błędu odcięcia dla mnożenia o stałej szerokości bitowej czyli takiej, dla której szerokość bitowa argumentów wejściowych jest taka sama jak wyjścia. Niektóre poprzednie publikacje były oparte na błędnych założeniach, dlatego zadaniem tej publikacji jest wykazanie wspomnianych błędów oraz zaprezentowanie nowej architektury, dla której błąd średni dąży do zera.

EN

Multiplication is usually implemented in hardware as a full bit-width parallel multiplier, i.e., input bit-widths add up to make up the output bit-width. Nevertheless, in most real-world cases, the input bit-width n is the same as the output bit-width. Therefore, in order to reduce a multiplier area, the n LSBs columns of the multiplier are truncated during the multiplication process (see Fig. 1). This introduces a truncation error which can be reduced by an error compensation circuit. The truncation errors presented in the previous papers, e.g. [3, 6, 7], are based on the false assumption; during truncation error calculation it is sufficient to consider only the combination of each partial input bit products aibj. instead of ever input bits ai and bj (see Fig. 2 and Tab. 1). Therefore a proper fixed-width multiplier structure should be introduced (the old one should be redesigned). This paper focuses on optimizing the mean error (ME) of the truncated multiplier. As a result, a novel Improved Variable error Compensation Truncated Multiplier (IVCTM) is proposed which in comparison to [2], reduces the number of AND gates by 1 in the error compensation circuit (see Fig. 3). For the IVCTM, a mean error is significantly lower than for previously published counterparts. The structure of the IVCTM is simplified in comparison to the previously published truncated multiplier [2], therefore it occupies less silicon area.