Leer y escribir puertos hardware directamente en modo usuario

__asm{    
  mov AX,3     // salida utilizando los pines 2 y 3    
  mov DX,0x378 // puerto paralelo 378h    
  OUT DX,AX    
} 

//---------------------------------------------------------------------------
#pragma hdrstop
 
//---------------------------------------------------------------------------
#pragma argsused
 
//------------------------------------------------------------------------
#include <windows.h>
#include <stdio.h>
 
//#pragma comment(lib, "advapi32")
//#pragma link "advapi32.lib"
 
#define NTAPI  __stdcall
 
typedef int NTSTATUS;
 
typedef enum _SYSDBG_COMMAND
{
  SysDbgSysReadIoSpace = 14,
  SysDbgSysWriteIoSpace = 15
}SYSDBG_COMMAND, *PSYSDBG_COMMAND;
 
typedef NTSTATUS (NTAPI * PZwSystemDebugControl) (
    SYSDBG_COMMAND ControlCode,
    PVOID InputBuffer,
    ULONG InputBufferLength,
    PVOID OutputBuffer,
    ULONG OutputBufferLength,
    PULONG ReturnLength
    );
 
PZwSystemDebugControl ZwSystemDebugControl = NULL;
 
typedef struct _IO_STRUCT
{
    DWORD IoAddr;       // IN: Aligned to NumBYTEs,I/O address
    DWORD Reserved1;    // Never accessed by the kernel
    PVOID pBuffer;      // IN (write) or OUT (read): Ptr to buffer
    DWORD NumBYTEs;     // IN: # BYTEs to read/write. Only use 1, 2, or 4.
    DWORD Reserved4;    // Must be 1
    DWORD Reserved5;    // Must be 0
    DWORD Reserved6;    // Must be 1
    DWORD Reserved7;    // Never accessed by the kernel
}
IO_STRUCT, *PIO_STRUCT;
 
BOOL EnablePrivilege (PCSTR name)
{
    HANDLE hToken;
    TOKEN_PRIVILEGES priv = {1, {0, 0, SE_PRIVILEGE_ENABLED}};
 
    LookupPrivilegeValue(0, name, &priv.Privileges[0].Luid);
    OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES, &hToken);
    AdjustTokenPrivileges (hToken, FALSE, &priv, sizeof priv, 0, 0);
    CloseHandle (hToken);
 
    return (GetLastError() == ERROR_SUCCESS);
}
 
BOOL Inicializa()
{
    HMODULE hNtdll;
    hNtdll = LoadLibrary ("ntdll.dll");
 
    if(EnablePrivilege(SE_DEBUG_NAME)==FALSE){
       printf("Usted no tiene suficientes privilegios\n");
       return FALSE;
    }
 
    if(hNtdll){
       ZwSystemDebugControl = (PZwSystemDebugControl)GetProcAddress(hNtdll, "ZwSystemDebugControl");
       return TRUE;
    }
    return FALSE;
}
 
BYTE InPortB(int Port)
{
    BYTE Value;
    IO_STRUCT io;
 
    io.IoAddr = Port;
    io.Reserved1 = 0;
    io.pBuffer = (PVOID)(PULONG)&Value;
    io.NumBYTEs = sizeof(BYTE);
    io.Reserved4 = 1;
    io.Reserved5 = 0;
    io.Reserved6 = 1;
    io.Reserved7 = 0;
 
    ZwSystemDebugControl(SysDbgSysReadIoSpace, &io, sizeof(io), NULL, 0, NULL);
    return Value;
}
 
void OutPortB(int Port, BYTE Value)
{
    IO_STRUCT io;
    
    io.IoAddr = Port;
    io.Reserved1 = 0;
    io.pBuffer = (PVOID)(PULONG)&Value;
    io.NumBYTEs = sizeof(BYTE);
    io.Reserved4 = 1;
    io.Reserved5 = 0;
    io.Reserved6 = 1;
    io.Reserved7 = 0;
    
    ZwSystemDebugControl(SysDbgSysWriteIoSpace, &io, sizeof(io), NULL, 0, NULL);
};
 
void BeepOn (int Freq)
{
    BYTE b;
 
    if((Freq >= 20) && (Freq <= 20000)){
        Freq = 1193181 / Freq;
        b = InPortB(0x61);
        if((b & 3) == 0){
           OutPortB (0x61, (BYTE) (b | 3));
           OutPortB (0x43, 0xb6);
        }
        OutPortB (0x42, (BYTE)Freq);
        OutPortB (0x42, (BYTE)(Freq >> 8));
    }
}
 
void BeepOff (void)
{
    BYTE b;
 
    b = (InPortB(0x61) & 0xfc);
    OutPortB(0x61, b);
}
 
// Sólo funciona en Windows XP y superiores
// Se debe ser Administrador del Sistema
int main(void)
{
    if(Inicializa()==FALSE){
       printf("Error al inicializar los puertos\n");
       Sleep (2000);
       return 0;
    }
 
    // Aquí­ podemos utilizar las funciones InPortB y OutPortB
 
    // Activamos el altavoz del sistema durante 300ms con una frecuencia
    // de 1000Hz
    BeepOn(1000);  // frecuencia de 1000Hz
    Sleep (300);
    BeepOff();
 
    return 0;
}

Inicializa();
BYTE B = InPortB(0x378);  // Lee del puerto paralelo
OutPortB(0x378, 3);       // Escribe en el puerto paralelo el valor 3

OutPort(0x378, 3);       // Escribe en el puerto paralelo el valor 3

OutPortB(0x378, 2); // 0000 0010b

BYTE A = 0x10;  // 0001 0000b
BYTE B = 0x04;  // 0000 0100b
BYTE C = A | B; // C == 0x14 ó 0001 0100b
OutPortB(0x378, C);