Chapter 5. Counting Bits - Hacker’s Delight, Second Edition [Book] (oreilly.com)
The IBM Stretch computer (about 1960) had a means of counting the number of 1-bits in a word... sometimes called population count
去掉查表法和用VPOPCNTDQ指令，还有n种方法：
Population Count - Chessprogramming wiki
bss segmentUsually refers to a memory area used to store uninitialized (or initialized to 0) global variables in the program.
The size of the BSS segment required for operation is recorded in the target file, but the BSS segment does not occupy any space in the target file.
The term BSS (Block Started by Symbol) was originally a pseudo-instruction in the UA-SAP assembler (United Aircraft Symbolic Assembly Program) to reserve a memory space for symbols. The assembler was developed by United Airlines for the IBM 704 mainframe in the mid-1950s.
标签：United,assembler,number,BSS,counting,bits From： https://www.cnblogs.com/funwithwords/p/16977624.html