Xchg Rax, Rax

Book excerpt: ; 0x40 assembly riddles "xchg rax, rax" is a collection of assembly gems and riddles I found over many years of reversing and writing assembly code. The book contains 0x40 short assembly snippets, each built to teach you one concept about assembly, math or life in general. Be warned - This book is not for beginners. It doesn't contain anything besides assembly code, and therefore some x86_64 assembly knowledge is required. How to use this book? Get an assembler (Yasm or Nasm is recommended), and obtain the x86_64 instruction set. Then for every snippet, try to understand what it does. Try to run it with different inputs if you don't understand it in the beginning. Look up for instructions you don't fully know in the Instruction sets PDF. Start from the beginning. The order has meaning. As a final note, the full contents of the book could be viewed for free on my website (Just google "xchg rax, rax").