cpu6502 | A 6502 Instruction Set Simulator | Build Tool library

 by   wyvernSemi C++ Version: Current License: GPL-3.0

kandi X-RAY | cpu6502 Summary

kandi X-RAY | cpu6502 Summary

cpu6502 is a C++ library typically used in Utilities, Build Tool applications. cpu6502 has no bugs, it has no vulnerabilities, it has a Strong Copyleft License and it has low support. You can download it from GitHub.

A 6502 Instruction Set Simulator. Includes a C++ model of the MOS 6502, with compile options, and an optional command line interface. A test program (modified) from Klaus Dormann (is included. An API is provided for integration with other applications---see src/cpu6502_api.h for more information. Support is provided for building under MSVC 2010 (cpu6502.sln) and Linux (makefile).
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              cpu6502 has a low active ecosystem.
              It has 5 star(s) with 0 fork(s). There are 2 watchers for this library.
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              It had no major release in the last 6 months.
              cpu6502 has no issues reported. There are no pull requests.
              It has a neutral sentiment in the developer community.
              The latest version of cpu6502 is current.

            kandi-Quality Quality

              cpu6502 has 0 bugs and 0 code smells.

            kandi-Security Security

              cpu6502 has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
              cpu6502 code analysis shows 0 unresolved vulnerabilities.
              There are 0 security hotspots that need review.

            kandi-License License

              cpu6502 is licensed under the GPL-3.0 License. This license is Strong Copyleft.
              Strong Copyleft licenses enforce sharing, and you can use them when creating open source projects.

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              cpu6502 releases are not available. You will need to build from source code and install.

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            cpu6502 Key Features

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            cpu6502 Examples and Code Snippets

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            Community Discussions

            QUESTION

            Go performance penalty in high number of calls to append
            Asked 2021-May-09 at 18:26

            I'm writing an emulator in Go, and for debugging purposes I'm logging the cpu' state at every emulator's cycle to generate a log file later.

            There's something I'm not doing properly because while the logger is enabled performance drops and makes the emulator unusable.

            Profiler shows clearly the culprit resides in the logging routine (logStep method):

            logStep method is very simple, it calls CreateState to snapshot current cpu state in a struct, and then adds it to a slice (in method Log).
            I call this method at every emulated cpu cycle (around 30.000 times per second), and I suspect either Garbage Collector is slowing my execution or I'm doing something wrong with this data structure.

            I get the profile graph is pointing me to runtime growslice caused by an append located in (*cpu6502Logger)Log, but I'm unable to find information on how to do this more efficiently.
            Also, I scratch my head on why CreateState takes that long to just create a simple struct.

            This is what CpuState looks like:

            ...

            ANSWER

            Answered 2021-May-09 at 18:26

            Disclaimer: following text contains grammar mistakes but i dont give a damn

            why is it slow

            Maintaining one gigantic slice to hold all data there is is wery costy mainly when it constantly extends. Each time you append few elements, whole memory section is copied to bigges section to allow expansion. with grownig slice, complexity grows and each realocation is slower and slower. You told us that you emulate tousands of cpu states per second.

            solution

            The best way to deal with this is allocating fixed buffer of some length. Now we now that eventually we will run out of space. When that happens we have two options. First you can write all data ftom buffer to file then truncate the buffer and start filling again (then write again). Other option is to save filled buffers in a slice and allocate new one. Choos witch one fits your machine. (slow or small ram is not good for second solution)

            why does this help

            i think this also helps the emulator it self. There will be performance spikes when restoring buffer, but most of the time, performance will be at maximum. Allocating big memory is just slow as alocator is less likely to find fitting section on first try. Garbage collection is also wery unhappy with frequent allocations. By allocating buffer and filling it, we use one big allocation, (but not too big), and store data in sections. Sections we already saved can stey where they are. We can also say that in this case we are handling memory our selfs more then gc does. (no garbage memory produced)

            Source https://stackoverflow.com/questions/67460680

            Community Discussions, Code Snippets contain sources that include Stack Exchange Network

            Vulnerabilities

            No vulnerabilities reported

            Install cpu6502

            You can download it from GitHub.

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            For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .
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