Foundations of Linux Debugging, Disassembling, and Reversing: Analyze Binary Code, Understand Stack Memory Usage, and Reconstruct C/C++ Code with Intel x64

© The Author(s), under exclusive license to APress Media, LLC, part of Springer Nature 2023

D. VostokovFoundations of Linux Debugging, Disassembling, and Reversinghttps://doi.org/10.1007/978-1-4842-9153-5_12

12. More Instructions

Dmitry Vostokov¹  

(1)

Dublin, Ireland

 

CPU Flags Register

In addition to registers, the CPU also contains a 64-bit %RFLAGS register where individual bits are set or cleared in response to arithmetic and other operations. Separate machine instructions can manipulate some bit values, and their values affect code execution.

For example, the DF bit (Direction Flag) determines the direction of memory copy operations and can be set by STD and cleared by CLD instructions. It has the default value of zero, and its location is shown ...