https://github.com/nikolaydubina/go-hackers-delight
"Hacker's Delight" in Go
https://github.com/nikolaydubina/go-hackers-delight
assembly binary bits book c logic risc showcase
Last synced: 3 months ago
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"Hacker's Delight" in Go
- Host: GitHub
- URL: https://github.com/nikolaydubina/go-hackers-delight
- Owner: nikolaydubina
- License: mit
- Created: 2024-05-11T06:20:23.000Z (about 1 year ago)
- Default Branch: master
- Last Pushed: 2025-02-18T14:35:41.000Z (4 months ago)
- Last Synced: 2025-03-31T08:12:03.772Z (3 months ago)
- Topics: assembly, binary, bits, book, c, logic, risc, showcase
- Language: Go
- Homepage:
- Size: 236 KB
- Stars: 100
- Watchers: 1
- Forks: 4
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# go-hackers-delight
[](https://codecov.io/gh/nikolaydubina/go-hackers-delight)
[](https://hits.sh/github.com/nikolaydubina/go-hackers-delight/)
[](https://pkg.go.dev/github.com/nikolaydubina/go-hackers-delight)
An interactive Go showcase of ["Hacker's Delight"](https://en.wikipedia.org/wiki/Hacker%27s_Delight) 2nd Edition by Henrey S.Warren Jr, 2013.[^1][^2]
> If you write optimizing compilers or high-performance code, you must read this book.
> — [Guy L. Steele](https://en.wikipedia.org/wiki/Guy_L._Steele_Jr.) [PhD, ACM Award, AAAI Fellow, Sun Fellow, core Java design]
> This is the first book that promises to tell the deep, dark secrets of computer arithmetic, and it delivers in spades. It contains every trick I knew plus many, many more.
> A godsend for library developers, compiler writers, and lovers of elegant hacks.
> It deserves a spot on your self right next to Knuth.
> In the ten years since the first edition came out, it's been absolutely invaluable to my work at Sun and Google.
> — [Joshua Bloch](https://en.wikipedia.org/wiki/Joshua_Bloch) [PhD, Distinguished Engineer at Sun, Chief Java Architect at Google 2004~2012]
### Methodology
* extensively fuzzing
* not using any Go packages, not even standard library
* using generics whenever possible
* verifying compiled code via https://godbolt.org
### Observations
* native `math.Pow(x, 1./3)`[^4] performance is worse than `Cbrt` algorithm 💥
* native `math.Pow(x, 1./3)`[^4][^5] underflows but `Cbrt` algorithm is correct 💥
* native `math.Pow(x, n)`[^4] performance is worse than `Pow` algorithm 💥
* native `math.Log2(x)`[^4] performance is worse than `Log2` algorithm 💥
* native `math.Log10(x)`[^4] performance is worse than `Log10` algorithm 💥
* native `math.Log10(x)` [^4][^5] overflows for `math.MaxUint64` but `Log10` algorithm is correct 💥
* simplistic `LRUCache` performance is `2x` worse than `LRUCache` algorithm 💥
Appendix: Benchmarks
```bash
$ go test -bench .
goos: darwin
goarch: arm64
pkg: github.com/nikolaydubina/go-hackers-delight
cpu: Apple M3 Max
BenchmarkNoop/---------------------------------16 1000000000 0.0000001 ns/op
BenchmarkAbs/basic-16 1489353 811.6 ns/op
BenchmarkAbs/Abs-16 1460946 818.8 ns/op
BenchmarkAbs/Abs2-16 1464883 816.4 ns/op
BenchmarkAbs/Abs3-16 1443763 830.9 ns/op
BenchmarkAbs/Abs4-16 1431141 882.4 ns/op
BenchmarkAbs/AbsFastMul-16 1494900 803.1 ns/op
BenchmarkAvg/basic-16 611107 1970 ns/op
BenchmarkAvg/AvgFloor-16 811885 1603 ns/op
BenchmarkAvg/AvgCeil-16 609648 1916 ns/op
BenchmarkCycleThree/basic-16 1000000000 1.105 ns/op
BenchmarkCycleThree/CycleThreeValues-16 1000000000 1.000 ns/op
BenchmarkLeadingZeros/uint32/basic-16 1474354 816.2 ns/op
BenchmarkLeadingZeros/uint32/LeadingZerosUint32-16 1000000 1174 ns/op
BenchmarkLeadingZeros/uint64/basic-16 1483987 808.8 ns/op
BenchmarkLeadingZeros/uint64/LeadingZerosUint64-16 892615 1349 ns/op
BenchmarkCompress/Compress-16 150361084 8.064 ns/op
BenchmarkCompress/Compress2-16 54269787 21.47 ns/op
BenchmarkLRU/basic-16 447112422 2.689 ns/op
BenchmarkLRU/LRUCache-16 625848724 1.878 ns/op
BenchmarkMul/uint32/basic-16 610756 1963 ns/op
BenchmarkMul/uint32/MultiplyHighOrder32-16 590781 1851 ns/op
BenchmarkMul/uint64/basic-16 109549 11017 ns/op
BenchmarkMul/uint64/MultiplyHighOrder64-16 71486 19700 ns/op
BenchmarkDivMod/DivMod/3/basic-16 1483515 809.9 ns/op
BenchmarkDivMod/DivMod/3/DivMod3Signed-16 630376 1903 ns/op
BenchmarkDivMod/DivMod/3/DivMod3Signed2-16 1000000 1078 ns/op
BenchmarkDivMod/DivMod/7/basic-16 1470925 813.2 ns/op
BenchmarkDivMod/DivMod/7/DivMod7Signed-16 617737 1977 ns/op
BenchmarkDivMod/Div/3/basic-16 1474382 816.0 ns/op
BenchmarkDivMod/Div/3/Div3Signed-16 855132 1387 ns/op
BenchmarkDivMod/Div/3/Div3ShiftSigned-16 958530 1245 ns/op
BenchmarkDivMod/Div/7/basic-16 1480100 808.9 ns/op
BenchmarkDivMod/Div/7/Div7Signed-16 831228 1438 ns/op
BenchmarkDivMod/Div/7/Div7ShiftSigned-16 890666 1347 ns/op
BenchmarkDivMod/Mod/3/basic-16 1494051 807.6 ns/op
BenchmarkDivMod/Mod/3/Mod3Signed-16 896326 1306 ns/op
BenchmarkDivMod/Mod/3/Mod3Signed2-16 1491132 804.5 ns/op
BenchmarkDivMod/Mod/7/basic-16 1489940 804.5 ns/op
BenchmarkDivMod/Mod/7/Mod7Signed-16 865971 1394 ns/op
BenchmarkDivMod/Mod/7/Mod7Signed2-16 1000000 1108 ns/op
BenchmarkDivMod/Mod/10/basic-16 1470753 816.9 ns/op
BenchmarkDivMod/Mod/10/Mod10Signed-16 1000000 1113 ns/op
BenchmarkDivMod/DivExact/7/basic-16 1492069 803.8 ns/op
BenchmarkDivMod/DivExact/7/DivExact7-16 1452621 820.2 ns/op
BenchmarkDivMod/DivExact/7/Div7Signed-16 763095 1558 ns/op
BenchmarkDivMod/DivExact/7/Div7ShiftSigned-16 869890 1382 ns/op
BenchmarkCbrt/basic-16 4669 260382 ns/op
BenchmarkCbrt/Cbrt-16 7956 150951 ns/op
BenchmarkPow/basic-16 2311 520212 ns/op
BenchmarkPow/Pow-16 6334 188887 ns/op
BenchmarkLog/uint32/2/basic-16 10000 120539 ns/op
BenchmarkLog/uint32/2/Log2-16 96388 12463 ns/op
BenchmarkLog/uint32/10/basic-16 13887 86154 ns/op
BenchmarkLog/uint32/10/Log10-16 54652 21962 ns/op
BenchmarkLog/uint64/2/basic-16 10000 120627 ns/op
BenchmarkLog/uint64/2/Log2-16 81048 15237 ns/op
BenchmarkLog/uint64/10/basic-16 14146 84683 ns/op
BenchmarkLog/uint64/10/Log10-16 51010 23544 ns/op
BenchmarkSqrt/basic-16 134250 8954 ns/op
BenchmarkSqrt/SqrtNewton-16 18208 63912 ns/op
BenchmarkSqrt/SqrtBinarySearch-16 7302 168653 ns/op
BenchmarkSqrt/SqrtShiftAndSubtract-16 10000 114464 ns/op
BenchmarkCRC32/basic-16 181860 6610 ns/op
BenchmarkCRC32/CRC32Basic-16 434 2778007 ns/op
BenchmarkCRC32/CRC32TableLookup-16 7068 168972 ns/op
BenchmarkRSqrtFloat32/basic-16 139954 8663 ns/op
BenchmarkRSqrtFloat32/RSqrtFloat32-16 99153 12287 ns/op
PASS
ok github.com/nikolaydubina/go-hackers-delight 83.522s
```
[^1]: showcase in `C` — https://github.com/hcs0/Hackers-Delight
[^2]: showcase in `Rust` — https://github.com/victoryang00/Delight
[^4]: we are comparing native float64 result converted to uint32, as there is no better standard function
[^5]: which is due to `float64` not having enough precision