The x86-64 processor has a number of instructions that provide the programmer with the ability to manipulate strings at a byte, word, double and quadruple word length. These instructions are, stosx, movsx, cmpsx. lodsx and scasx, and can be combined with conditional repeat mnemonics, these are rep, repe, repne, repz, and repnz, and they are convenient because they let you avoid writing lots of little loops, which can make the code really bad for the readers . The “x” represent the size of the basic unit, these units are b, byte, w word, d doubleword, and q quadword respectively.
The main goal of this paper is to provide some knowledge about string manipulation, without using the common instruction set.
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