Add benchmark for initilizing an array of 32 & 64 bytes

[codecov[bot]]

Codecov Report

Merging #487 into master will not change coverage. The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #487   +/-   ##
=======================================
  Coverage   63.00%   63.00%           
=======================================
  Files         165      165           
  Lines        8771     8771           
  Branches     1448     1448           
=======================================
  Hits         5526     5526           
  Misses       2723     2723           
  Partials      522      522           

Impacted Files	Coverage Δ
src/JsonWebToken/Cryptography/Sha256.cs	96.00% <100.00%> (ø)
src/JsonWebToken/Cryptography/Sha384.cs	75.24% <100.00%> (ø)
src/JsonWebToken/Cryptography/Sha512.cs	93.14% <100.00%> (ø)

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[ycrumeyrolle]

The main benefit of the Unsafe.CopyBlock come from the jitter that is able to identify a constant sized byte array and to vectorize the copy.

Method	Mean	Error	StdDev	Ratio	RatioSD	Code Size
InitUint32_Original	2.6049 ns	0.0357 ns	0.0316 ns	1.00	0.00	128 B
InitUint32_UnsafeCopyBlock	0.7034 ns	0.0538 ns	0.0681 ns	0.27	0.03	104 B
InitUint32_UnsafeCopyBlockUnaligned	1.0163 ns	0.0522 ns	0.0536 ns	0.39	0.02	104 B
InitUint32_SpanCopyTo	3.4210 ns	0.0961 ns	0.1107 ns	1.32	0.04	426 B
InitUint64_Original	4.0400 ns	0.1044 ns	0.1025 ns	1.55	0.04	185 B
InitUint64_UnsafeCopyBlockUnaligned	2.9553 ns	0.0524 ns	0.0409 ns	1.13	0.01	125 B
InitUint64_UnsafeCopyBlock	2.9520 ns	0.0556 ns	0.0492 ns	1.13	0.02	125 B
InitUint64_SpanCopyTo	5.3443 ns	0.1144 ns	0.1405 ns	2.06	0.06	436 B