Decode BAM sequence with less code. Dispatch function at dynamic link time rather than at run time.

[rhpvorderman]

Two improvements coming from htslib. Credit for simplifying the bam decode goes to @jmarshall.

See: samtools/htslib#1795

For the use of constructor:
samtools/htslib#1786

Using the constructor attribute makes the code simpler. Another change is that the fallback code now also always use a function pointer and cannot inline. This also makes the code simpler.

[rhpvorderman]

@marcelm, friendly reminder ping. This exact code is already merged in htslib. I hope you had a nice holiday!

[marcelm]

Still not really working fully, but if it’s identical to what is in htslib, I’ll just merge it.

[rhpvorderman]

Still not really working fully

I don't understand, can you elaborate?

[marcelm]

I am still on vacation and don’t systematically do work-related things that are on my to-do list, only some things that I feel like doing. I’ll be back at work middle of August.

[rhpvorderman]

Oh sorry. I saw a github reply somewhere and assumed you were back. I won't ping you anymore before the middle of August.

[marcelm]

Yes, I thought so (that you saw something from me), which is why I shouldn’t have done anything at all ;-).

[rhpvorderman]

Well now that I am in the know I won't do it anymore ;-). Fun fact: I wrote this code during my holiday. Writing assembly in the form of intrinsics is simply too much fun.