1.1.3-Constructing Assembly statements

Recently intends to "old code to know the way" to do it again, the first to take the structure of the assembly sentence surgery.

1.1.3

Embed assembly statements in the C language to construct machine instructions for MOV and JMP, allowing the program to run at its own specified path.

See Code:

1#include <stdio.h>2#include <string.h>3#include <stdlib.h>4 5 intgi;6 void*address;7 8 void*Buildcode ();9 Ten intMain () { One     void*code=Buildcode (); A _asm { - mov address,offset _lb1 -     } theGi= A; -printf"gi=%d\n", GI); - _asm jmp Code -Gi= -; + _LB1: -printf"gi=%d\n", GI);//Output + GetChar (); A     return 0; at } - void*Buildcode () { -     Char*code= (Char*)malloc( -); -     Char*pmov=Code; -     Char*pjmp=code+Ten; -     Char*paddress; in     //mov gi,18 -pmov[0]=0xc7; topmov[1]=0x05; +paddress=pmov+2; -*((int*) paddress) = (int) &gi; the*((int*) (paddress+4))= -; *     //JMP Address $pjmp[0]=0xFF;Panax Notoginsengpjmp[1]=0x25; -*((int*) (&pjmp[2]))=(int) &address; the     returnCode; +}

Buildcode () is to construct a two-sentence assembly instruction at code, which runs the code at _LB1, outputting 18.

Disassembly View Code:

The code was constructed successfully.

1.1.3-Constructing Assembly statements