I am trying to interpret the sam output, especially the cigar string in the sam alignment output, e.g.:

NM_017922.fs.chr14.45578967-45578983.16.45579296-45579310.14 0 chr14 45578971 255 3S13M313N8M6S * 0 0 GGGGTTTTGGATTAAGTATGCCAATTAAAT *

NH:i:1 HI:i:1 AS:i:21 nM:i:0

cigar string: 3S13M313N8M6S

I probably know what it indicates, but I need some sort of algorithm to calculate the values in cigar string, to see if the alignment match where it should align to (the information is stored in read name: NM_017922.fs.chr14.45578967-45578983.16.45579296-45579310.14)