usbloadergx/source/patches/dolpatcher.c

#include <string.h>
#include <gctypes.h>

bool PatchDOL(u8 * Address, int Size, const u8 * SearchPattern, int SearchSize, const u8 * PatchData, int PatchSize)
{
    u8 * Addr = Address;
    u8 * Addr_end = Address+Size;

    while(Addr <= Addr_end-SearchSize)
    {
        if(memcmp(Addr, SearchPattern, SearchSize)==0)
        {
            memcpy(Addr, PatchData, PatchSize);
            return true;
        }
        Addr += 4;
    }
	return false;
}