Inverting or flipping the bits of an integer is the third and last method of “bit bashing” we will discuss. There are two ways to invert bits: either flip all of them at once or use a mask to identify which bits to flip and which to leave alone.

All areas of computing, from data compression to web design, from networking to digital image storage, from system administration to high-performance computing, benefit from bit manipulation.

Clearing bits within an integer is important if we want to isolate bits or set them to zero before we insert a new value. The bitwise-AND does this for us.

Discussing how to use bitwise operations to manipulate the bits of an integer would be academic if we couldn’t perform the operations in our code. The good news is that we can!

The ability to set bits may not seem important at first, but many algorithms in computing depend on just that. Join us as we control bits and build integers from scratch using the bitwise-OR.

This report investigates the viability of bitwise operations on non-scarce attribute based data structures in PostgreSQL. For applications where computation can’t be avoided, it most probably can be optimized. In an attempt of bringing the computation closer to hardware and the underlying data, operations directly on the database system are explored, taking inspiration from the research field of comparative genomics. With the case-study of an online job platform in mind, where possible matchings between candidate and job descriptions are calculated by a matching engine, a binary encoding is proposed and the computational components identified. The ultimate goal was to evaluate the scalability of the bitwise strategy with respect to the current matching engine. Through an iterative approach, this report conducts quantitative experiments on the presented components. Most notably, an implementation of the population count in the form of a C extension was introduced. It was found, that even for large sequence lengths, the operation is highly efficient. Among the chosen algorithms Lookup Table, Hamming Weight, Intrinsic functions and Unrolled Inline Assembly, the 64 bit intrinsic function displayed the best performance. Benchmarks determined, that the proposed bitwise approach is an excellent strategy for the outlined use-case. Despite the tradeoff of additional complexity in the encoding and decoding of data, the speedup is so significant, that the targeted user base of 100000 can easily be managed and allows for the deprecation of caching mechanisms. / Denna rapport undersöker gångbarheten för bitwise-operationer på icke-knappa attributbaserade datastrukturer i PostgreSQL. För applikationer där komputationen inte kan undvikas, kan den högst troligen optimeras. I ett försök att föra beräkningen närmare hårdvaran och den underliggande datan, undersöks operationer direkt på databasen med inspiration från forskningsområdet inom komparativ genomik. Med fallstudien av en online rekryteringsplattform i åtanke, där möjliga matchningar mellan kandidatoch arbetsbeskrivningar beräknas av en matchningsmotor, föreslås en binär kodning och komputationskomponenterna identifieras. Det slutgiltiga målet var att utvärdera skalbarheten hos bitwise-strategin med avseende till den aktuella matchningsmotorn. Genom ett iterativ tillvägagångssätt utför denna rapport kvantitativa experiment på de presenterade komponenterna. Framför allt infördes en implementering av population count i form av ett C-tillägg i databasen. Det visade sig att även för större sekvenslängder är operationen mycket effektiv. Bland de utvalda algoritmerna Lookup Table, Hamming Weight, Intrinsic-funktioner och Unrolled Inline Assembly, visade 64-bitars Intrisicfunktionen den bästa prestandan. Experimenten fastställde att det föreslagna bitwisetillvägagångssättet är en utmärkt strategi för den valda fallstudien. Trots avvägningen med ytterligare komplexitet vid kodning och avkodning av data är hastigheten så signifikant att ett användarantal på 100000 enkelt kan hanteras och möjliggör uteslutning av cache-mekanismer.

Cryptography plays a crucial role in today’s society. Given the influence, cryptographic algorithms need to be trustworthy. Cryptographic algorithms such as RSA relies on the problem of prime number factorization to provide its confidentiality. Hence finding a way to make it computationally feasible to find the prime factors of any integer would break RSA’s confidentiality. The approach presented in this thesis explores the possibility of trying to construct φ(n) from n. This enables factorization of n into its two prime numbers p and q through the method presented in the original RSA paper. The construction of φ(n) from n is achieved by analyzing bitwise relations between the two. While there are some limitations on p and q this thesis can in favorable circumstances construct about half of the bits in φ(n) from n. Moreover, based on the research a conjecture has been proposed which outlines further characteristics between n and φ(n).

Autonomous cars are developing in a rapid speed, which means that the advanced driver-assistance systems must be tested carefully. Radar is one of many tools the car can use to detect obstacles and targets in front of the car. This bachelor thesis deals with programming and testing of an FMCW radar. The radar used in this thesis is an Continental ARS 308-2C/21 HS/AO, and the programming is written in Visual Basic. The goal within this project was to write a program for the Continental radar, and then measure static objects. The radar and the written program will be used in the research project, "HiFi Radar Target". The radar module will also be implemented in the new EMC chamber, AWITAR, which is currently under construction. The radar sweeps in the frequency band 77GHz, which is a standard frequency in the automotive industry. Communication with the computer is done via a CAN-network. Function tests have been performed on Astazero and gave satisfactory results.The thesis work has been carried out at RISE in Borås. / Idag är självkörande bilar på kraftig frammarsch, detta medför att hjälpsystemen måste testas noga. Radar är ett av många hjälpmedel bilen kan använda för att detektera hinder framför bilen. Detta examensarbete avhandlar programering och testning av en FMCW radar. Radarn som används är en Continental ARS 308-2C/21 HS/AO, programeringen är skriven i Visual Basic. Målet med detta examensarbeta var att få radarn att fungera, för att sedan kunna mäta på statinära objekt. Radarn och det skrivna programmet kommer att användas inom forskningsprojektet, "HiFi Radar Target". Radarmodulen kommer även att implementeras i den nya EMC-kammaren, AWITAR som just nu är under konstruktion. Radarn sweper i freqvensbandet 77GHz, vilket är en standardfreqvens för bilindustrin. All kommunikation med radarn och datorn sker via ett CAN-nätverk. Funktionstesterna har utförts på Astazero och gav tillfredställande resultat. Examensarbetet är utfört på RISE i Borås.

Most of the modern wireless communication systems as WiMAX, DVB-NGH, WiFi, HSPA+ and 4G have adopted the use of multiple antennas at the transmitter and the receiver, called multiple-input multiple-output (MIMO). Space time coding for MIMO systems is a promising technology to increase the data rate and enhance the reliability of wireless communications. Space-time block codes (STBCs) are commonly designed according to the rank-determinant criteria suitable at high signal to noise ratios (SNRs). In contrast, wireless communication standards employ MIMO technology with capacity-approaching forward-error correcting (FEC) codes like turbo codes and low-density parity-check (LDPC) codes, ensuring low error rates even at low SNRs. In this thesis, we investigate the design of STBCs for MIMO systems with capacity-approaching FEC codes. We start by proposing a non-asymptotic STBC design criterion based on the bitwise mutual information (BMI) maximization between transmitted and soft estimated bits at a specific target SNR. According to the BMI criterion, we optimize several conventional STBCs. Their design parameters are shown to be SNR-dependent leading to the proposal of adaptive STBCs. Proposed adaptive STBCs offer identical or better performance than standard WiMAX profiles for all coding rates, without increasing the detection complexity. Among them, the proposed adaptive trace-orthonormal STBC can pass continuously from spatial multiplexing, suitable at low SNRs and therefore at low coding rates, to the Golden code, optimal at high SNRs. Uncorrelated, correlated channels and transmit antenna selection are considered. We design adaptive STBCs for these cases offering identical or better performance than conventional non-adaptive STBCs. In addition, conventional STBCs are designed in a way achieving the asymptotic DMT frontier. Recently, the finite-SNR DMT has been proposed to characterize the DMT at finite SNRs. Our last contribution consists of the derivation of the exact finite-SNR DMT for MIMO channels with dual antennas at the transmitter and/or the receiver. Both uncorrelated and correlated Rayleigh fading channels are considered. It is shown that at realistic SNRs, achievable diversity gains are significantly lower than asymptotic values. This finite-SNR could provide new insights on the design of STBCs at operational SNRs.

This work focuses on proposition of transfer of the expressions entered in the C pro­gramming language into DIMACS format and creation of program in programming language C++ making this transfer. This work contains a description of the C pro­gramming language and its operators. It also con­tains a description of the conjunctive normal form and a descri­ption of the DIMACS format. Following is a proposal for a program for the transfer of expression in the C programming language to the DIMACS format and description of reali­zation of program performing this transfer.