I am working with a large output bam files generated from the STAR aligner. The alignment is done with hg38. I would like to split these bam files to the region of interest, for instance, chromosome number or coordinates so that I could reduce the computational power. Furthermore, I would also like to do the same with the human gene annotation file- split by their chromosome number. After splitting, I would take these split files and do a quick analysis. I believe there is a tool to do that but I'm not sure which one works the best. Could someone please point me to a specific solution to this problem? Thanks!