Fast Integer Log2 in C#

Benchmark several others and also some of my own.

Created by Ryan S. White (sunsetQuest) on 10/13/2019, 11/29/2020

Licensed under MIT

Goals:

1. benchmark a large set of known methods
2. see if I can get 1st place (the fun part)

Also known as

"SIZE - leading zero Count" UInt32[1->31, 2->30 3->30, 4->29] "Floor Log2" [1->0, 2->1 3->1, 4->2] "Bit Scan Reverse" [1->0, 2->1 3->1, 4->2] "find last set" "most significant set bit"

Benchmark results

Using: (AMD Ryzen CPU, Release mode, no-debugger attached, .net core 2.1

                        1-2^32              32-Bit     Zero
Name                    ticks     Errors     Support  Support
=============================================================
LeadingZeroCountSunset   2         0         Yes       Yes
BitOpsLog2SunsetQuest    2         0         Yes       Yes
Log2_SunsetQuest5        15        0         Yes       No
Log2_SunsetQuest4        17        0         Yes       No
Log2_SunsetQuest3        17        255       Yes       No
MostSigBit_spender       18        0         Yes       Yes
Log2_SPWorley            18        2         Yes       Yes
FloorLg2_Matthew_Watson  22        0         Yes       Yes
Log2_DanielSig           27        312500    No        Yes
Log2_HarrySvensson       30        0         Yes       Yes
Log2_WiegleyJ            31        0         Yes       Yes
Log2_SunsetQuest1        34        0         Yes       Yes
highestBitUnrolled_Kaz   37        312500    Yes       Yes
getMsb_user3177100       68        0         Yes       Yes
Msb_Protagonist          69        0         Yes       Yes
Log2_Flynn1179           70        0         Yes       Yes
Log2_Papayaved           87        0         Yes       Yes
log2floor_greggo         90        0         Yes       Yes
FloorLog2_SN17           98        0         Yes       Yes
Log2_SunsetQuest2        133       0         Yes       Yes
Log2_SunsetQuest0        212       0         Yes       Yes
BitScanReverse_Other     828       0         Yes       Yes
UsingStrings_Other       2116      0         Yes       Yes



    
Zero_Support = Supports Zero if the result is 0 or less
Full-32-Bit  = Supports full 32-bit (some just support 31 bits)
Time4 = .Net 5.0 (note: because random was not used some compiler optimization might have been applied so this result might not be accurate) 

And the winner is...

Fast, safe, and portable

    BitOperations.Log2(x);