src/haptic/win32/SDL_syshaptic.c

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 2008 Edgar Simo

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

#ifdef SDL_HAPTIC_DINPUT

#include "SDL_haptic.h"
#include "../SDL_syshaptic.h"
#include "SDL_joystick.h"
#include "../../joystick/SDL_sysjoystick.h" /* For the real SDL_Joystick */
/*#include "../../joystick/win32/SDL_sysjoystick_c.h"*/ /* For joystick hwdata */ 

#define WIN32_LEAN_AND_MEAN
#include <windows.h>

#define DIRECTINPUT_VERSION 0x0700 /* Need at least DirectX 7 for dwStartDelay */
#include <dinput.h>
#include <dxerr.h>
#ifdef _MSC_VER
#  pragma comment (lib, "dinput8.lib")
#  pragma comment (lib, "dxguid.lib")
#  pragma comment (lib, "dxerr.lib")
#endif /* _MSC_VER */

    /* an ISO hack for VisualC++ */
#ifdef _MSC_VER
#define   snprintf   _snprintf
#endif /* _MSC_VER */


#define MAX_HAPTICS  32


/*
 * List of available haptic devices.
 */
static struct
{
   DIDEVICEINSTANCE instance;
   SDL_Haptic *haptic;
} SDL_hapticlist[MAX_HAPTICS];


/*
 * Haptic system hardware data.
 */
struct haptic_hwdata
{
   LPDIRECTINPUTDEVICE2 device;
   /* DIDEVCAPS capabilities; */
};


/*
 * Haptic system effect data.
 */
struct haptic_hweffect
{
   DIEFFECT effect;
   LPDIRECTINPUTEFFECT ref;
};


/*
 * Internal stuff.
 */
static LPDIRECTINPUT dinput = NULL;


/*
 * External stuff.
 */
extern HINSTANCE SDL_Instance;
extern HWND SDL_HelperWindow;


/*
 * Prototypes.
 */
static BOOL CALLBACK EnumHapticsCallback(const DIDEVICEINSTANCE * pdidInstance, VOID * pContext);


/* 
 * Like SDL_SetError but for DX error codes.
 */
static void
DI_SetError(const char *str, HRESULT err)
{
   SDL_SetError( "Haptic: %s - %s: %s", str,
                 DXGetErrorString(err),
                 DXGetErrorDescription(err));
}


/*
 * Initializes the haptic subsystem.
 */
int
SDL_SYS_HapticInit(void)
{
   HRESULT ret;

   if (dinput != NULL) { /* Already open. */
      SDL_SetError("Haptic: SubSystem already open.");
      return -1;
   }

   /* Clear all the memory. */
   SDL_memset(SDL_hapticlist, 0, sizeof(SDL_hapticlist));

   SDL_numhaptics = 0;

   ret = CoInitialize(NULL);
   if (FAILED(ret)) {
      DI_SetError("Coinitialize",ret);
      return -1;
   }

   ret = CoCreateInstance(&CLSID_DirectInput, NULL, CLSCTX_INPROC_SERVER,
                          &IID_IDirectInput, &dinput);
   if (FAILED(ret)) {
      DI_SetError("CoCreateInstance",ret);
      return -1;
   }

   /* Because we used CoCreateInstance, we need to Initialize it, first. */
   ret = IDirectInput_Initialize(dinput, SDL_Instance, DIRECTINPUT_VERSION);
   if (FAILED(ret)) {
      DI_SetError("Initializing DirectInput device",ret);
      return -1;
   }

   /* Look for haptic devices. */
   ret = IDirectInput_EnumDevices( dinput,
                                   DIDEVTYPE_DEVICE,
                                   EnumHapticsCallback,
                                   NULL, DIEDFL_FORCEFEEDBACK | DIEDFL_ATTACHEDONLY);
   if (FAILED(ret)) {
      DI_SetError("Enumerating DirectInput devices",ret);
      return -1;
   }

   return SDL_numhaptics;
}

/*
 * Callback to find the haptic devices.
 */
static BOOL CALLBACK
EnumHapticsCallback(const DIDEVICEINSTANCE * pdidInstance, VOID * pContext)
{
   SDL_memcpy(&SDL_hapticlist[SDL_numhaptics].instance, pdidInstance,
         sizeof(DIDEVICEINSTANCE));
   SDL_numhaptics++;

   if (SDL_numhaptics >= MAX_HAPTICS)
      return DIENUM_STOP;

   return DIENUM_CONTINUE;
}


/*
 * Return the name of a haptic device, does not need to be opened.
 */
const char *
SDL_SYS_HapticName(int index)
{
   return SDL_hapticlist[index].instance.tszProductName;
}


/*
 * Callback to get all supported effects.
 */
#define EFFECT_TEST(e,s)   \
if ((pei->guid->Data1 == e.Data1) &&   \
      (pei->guid->Data2 == e.Data2) && \
      (pei->guid->Data3 == e.Data3) && \
      (SDL_strcmp(pei->guid->Data4,e.Data4)==0) \
   haptic->supported |= (s)
static BOOL CALLBACK
DI_EffectCallback(LPCDIEFFECTINFO pei, LPVOID pv)
{
   /* Prepare the haptic device. */
   SDL_Haptic *haptic = (SDL_Haptic*) pv;
   haptic->supported = 0;

   /* Get supported. */
   EFFECT_TEST(GUID_Spring,         SDL_HAPTIC_SPRING);
   EFFECT_TEST(GUID_Damper,         SDL_HAPTIC_DAMPER);
   EFFECT_TEST(GUID_Inertia,        SDL_HAPTIC_INERTIA);
   EFFECT_TEST(GUID_Friction,       SDL_HAPTIC_FRICTION);
   EFFECT_TEST(GUID_ConstantForce,  SDL_HAPTIC_CONSTANT);
   EFFECT_TEST(GUID_CustomForce,    SDL_HAPTIC_CUSTOM);
   EFFECT_TEST(GUID_Sine,           SDL_HAPTIC_SINE);
   EFFECT_TEST(GUID_Square,         SDL_HAPTIC_SQUARE);
   EFFECT_TEST(GUID_Triangle,       SDL_HAPTIC_TRIANGLE);
   EFFECT_TEST(GUID_SawtoothUp,     SDL_HAPTIC_SAWTOOTHUP);
   EFFECT_TEST(GUID_SawtoothDown,   SDL_HAPTIC_SAWTOOTHDOWN);
   EFFECT_TEST(GUID_RampForce,      SDL_HAPTIC_RAMP);
  
   /* Check for more. */
   return DIENUM_CONTINUE;
}


/*
 * Opens the haptic device from the file descriptor.
 *
 *    Steps:
 *       - Open temporary DirectInputDevice interface.
 *       - Create DirectInputDevice2 interface.
 *       - Release DirectInputDevice interface.
 *       - Set cooperative level.
 *       - Set data format.
 *       - Get capabilities.
 *       - Acquire exclusiveness.
 *       - Reset actuators.
 *       - Get supported featuers.
 */
static int
SDL_SYS_HapticOpenFromInstance(SDL_Haptic * haptic, DIDEVICEINSTANCE instance)
{
   HRESULT ret;
   LPDIRECTINPUTDEVICE device;
   DIPROPDWORD dipdw;

   /* Allocate the hwdata */
   haptic->hwdata = (struct haptic_hwdata *)
         SDL_malloc(sizeof(*haptic->hwdata));
   if (haptic->hwdata == NULL) {
      SDL_OutOfMemory();
      goto creat_err;
   }
   SDL_memset(haptic->hwdata, 0, sizeof(*haptic->hwdata));
  
   /* Open the device */
   ret = IDirectInput_CreateDevice( dinput, &instance.guidInstance,
                                    &device, NULL );
   if (FAILED(ret)) {
      DI_SetError("Creating DirectInput device",ret);
      goto creat_err;
   }

   /* Now get the IDirectInputDevice2 interface, instead. */
   ret = IDirectInputDevice_QueryInterface( device,
                                            &IID_IDirectInputDevice2,
                                            (LPVOID *) &haptic->hwdata->device );
   /* Done with the temporary one now. */
   IDirectInputDevice_Release(device);
   if (FAILED(ret)) {
      DI_SetError("Querying DirectInput interface",ret);
      goto creat_err;
   }

   /* Grab it exclusively to use force feedback stuff. */
   ret =IDirectInputDevice2_SetCooperativeLevel( haptic->hwdata->device,
                                                 SDL_HelperWindow,
                                                 DISCL_EXCLUSIVE | DISCL_BACKGROUND );
   if (FAILED(ret)) {
      DI_SetError("Setting cooperative level to exclusive",ret);
      goto acquire_err;
   }

   /* Set data format. */
   ret = IDirectInputDevice2_SetDataFormat( haptic->hwdata->device,
                                            &c_dfDIJoystick2 );
   if (FAILED(ret)) {
      DI_SetError("Setting data format",ret);
      goto query_err;
   }

#if 0
   /* Get capabilities. */
   ret = IDirectInputDevice2_GetCapabilities( haptic->hwdata->device,
                                              &haptic->hwdata->capabilities );
   if (FAILED(ret)) {
      DI_SetError("Getting device capabilities",ret);
      goto acquire_err;
   }
#endif

   /* Acquire the device. */
   ret = IDirectInputDevice2_Acquire(haptic->hwdata->device);
   if (FAILED(ret)) {
      DI_SetError("Acquiring DirectInput device",ret);
      goto query_err;
   }

   /* Reset all actuators - just in case. */
   ret = IDirectInputDevice2_SendForceFeedbackCommand( haptic->hwdata->device,
                                                       DISFFC_RESET );
   if (FAILED(ret)) {
      DI_SetError("Resetting device",ret);
      goto acquire_err;
   }


   /* Enabling actuators. */
   ret = IDirectInputDevice2_SendForceFeedbackCommand( haptic->hwdata->device,
                                                       DISFFC_SETACTUATORSON );
   if (FAILED(ret)) {
      DI_SetError("Enabling actuators",ret);
      goto acquire_err;
   }

   /* Get supported effects. */
   ret = IDirectInputDevice2_EnumEffects( haptic->hwdata->device, 
                                          DI_EffectCallback, haptic, DIEFT_ALL );
   if (FAILED(ret)) {
      DI_SetError("Enumerating supported effects",ret);
      goto acquire_err;
   }
   if (haptic->supported == 0) { /* Error since device supports nothing. */
      SDL_SetError("Haptic: Internal error on finding supported effects.");
      goto acquire_err;
   }

   /* Check autogain and autocenter. */
   dipdw.diph.dwSize       = sizeof(DIPROPDWORD); 
   dipdw.diph.dwHeaderSize = sizeof(DIPROPHEADER); 
   dipdw.diph.dwObj        = 0;
   dipdw.diph.dwHow        = DIPH_DEVICE;
   dipdw.dwData            = 10000;
   ret = IDirectInputDevice2_SetProperty( haptic->hwdata->device,        
                                          DIPROP_FFGAIN, &dipdw.diph );
   if (FAILED(ret)) {
      if (ret != DIERR_UNSUPPORTED) {
         DI_SetError("Checking gain",ret);
         goto acquire_err;
      }
   }
   else { /* Gain is supported. */
      haptic->supported |= SDL_HAPTIC_GAIN;
   }
   dipdw.dwData            = DIPROPAUTOCENTER_OFF;
   ret = IDirectInputDevice2_SetProperty( haptic->hwdata->device,
                                          DIPROP_AUTOCENTER, &dipdw.diph );
   if (FAILED(ret)) {
      if (ret != DIERR_UNSUPPORTED) {
         DI_SetError("Checking autocenter",ret);
         goto acquire_err;
      }
   }
   else { /* Autocenter is supported. */
      haptic->supported |= SDL_HAPTIC_AUTOCENTER;
   }


   /* Check maximum effects. */
   haptic->neffects = 128; /* TODO actually figure this out. */
   haptic->nplaying = 128;


   /* Prepare effects memory. */
   haptic->effects = (struct haptic_effect *)
         SDL_malloc(sizeof(struct haptic_effect) * haptic->neffects);
   if (haptic->effects == NULL) {
      SDL_OutOfMemory();
      goto acquire_err;
   }
   /* Clear the memory */
   SDL_memset(haptic->effects, 0,
         sizeof(struct haptic_effect) * haptic->neffects);
   
   return 0;
   
   /* Error handling */
acquire_err:
   IDirectInputDevice2_Unacquire(haptic->hwdata->device);
query_err:
   IDirectInputDevice2_Release(haptic->hwdata->device);   
creat_err:
   if (haptic->hwdata != NULL) {
      SDL_free(haptic->hwdata);
      haptic->hwdata = NULL;                                              
   }
   return -1;

}


/*
 * Opens a haptic device for usage.
 */
int
SDL_SYS_HapticOpen(SDL_Haptic * haptic)
{
   return SDL_SYS_HapticOpenFromInstance( haptic,
         SDL_hapticlist[haptic->index].instance );
}


/*
 * Opens a haptic device from first mouse it finds for usage.
 */
int
SDL_SYS_HapticMouse(void)
{
   return -1;
}


/*
 * Checks to see if a joystick has haptic features.
 */
int
SDL_SYS_JoystickIsHaptic(SDL_Joystick * joystick)
{
   return SDL_FALSE;
}


/*
 * Checks to see if the haptic device and joystick and in reality the same.
 */
int
SDL_SYS_JoystickSameHaptic(SDL_Haptic * haptic, SDL_Joystick * joystick)
{
   return 0;
}


/*
 * Opens a SDL_Haptic from a SDL_Joystick.
 */
int
SDL_SYS_HapticOpenFromJoystick(SDL_Haptic * haptic, SDL_Joystick * joystick)
{
   return -1;
}


/*
 * Closes the haptic device.
 */
void
SDL_SYS_HapticClose(SDL_Haptic * haptic)
{
   if (haptic->hwdata) {

      /* Free effects. */
      SDL_free(haptic->effects);
      haptic->effects = NULL;
      haptic->neffects = 0;

      /* Clean up */
      IDirectInputDevice2_Unacquire(haptic->hwdata->device);
      IDirectInputDevice2_Release(haptic->hwdata->device);   

      /* Free */
      SDL_free(haptic->hwdata);
      haptic->hwdata = NULL;
   }
}


/* 
 * Clean up after system specific haptic stuff
 */
void
SDL_SYS_HapticQuit(void)
{
   IDirectInput_Release(dinput);
   dinput = NULL;
}


/*
 * Converts an SDL trigger button to an DIEFFECT trigger button.
 */
static DWORD
DIGetTriggerButton( Uint16 button )
{
   DWORD dwTriggerButton;
   
   dwTriggerButton = DIEB_NOTRIGGER;
   
   if (button != 0) {
      dwTriggerButton = DIJOFS_BUTTON(button - 1);
   }                                                                      
                                                                          
   return dwTriggerButton;
}


/*
 * Sets the direction.
 */
static int
SDL_SYS_SetDirection( DIEFFECT * effect, SDL_HapticDirection *dir, int naxes )
{
   LONG *rglDir;

   /* Handle no axes a part. */
   if (naxes == 0) {
      effect->rglDirection = NULL;
      return 0;
   }

   /* Has axes. */
   rglDir = SDL_malloc( sizeof(LONG) * naxes );
   if (rglDir == NULL) {
      SDL_OutOfMemory();
      return -1;
   }
   SDL_memset( rglDir, 0, sizeof(LONG) * naxes );
   effect->rglDirection = rglDir;

   switch (dir->type) {
      case SDL_HAPTIC_POLAR:
         effect->dwFlags |= DIEFF_POLAR;
         rglDir[0] = dir->dir[0];
         return 0;
      case SDL_HAPTIC_CARTESIAN:
         effect->dwFlags |= DIEFF_CARTESIAN;
         rglDir[0] = dir->dir[0];
         rglDir[1] = dir->dir[1];
         rglDir[2] = dir->dir[2];
         return 0;
      case SDL_HAPTIC_SPHERICAL:
         effect->dwFlags |= DIEFF_SPHERICAL;
         rglDir[0] = dir->dir[0];
         rglDir[1] = dir->dir[1];
         rglDir[2] = dir->dir[2];
         return 0;

      default:
         SDL_SetError("Haptic: Unknown direction type.");
         return -1;
   }
}

#define CONVERT(x)   (((x)*10000) / 0xFFFF )
/*
 * Creates the DIEFFECT from a SDL_HapticEffect.
 */
static int
SDL_SYS_ToDIEFFECT( SDL_Haptic * haptic, DIEFFECT * dest, SDL_HapticEffect * src )
{
   int i;
   DICONSTANTFORCE *constant;
   DIPERIODIC *periodic;
   DICONDITION *condition; /* Actually an array of conditions - one per axis. */
   DIRAMPFORCE *ramp;
   DICUSTOMFORCE *custom;
   DIENVELOPE *envelope;
   SDL_HapticConstant *hap_constant;
   SDL_HapticPeriodic *hap_periodic;
   SDL_HapticCondition *hap_condition;
   SDL_HapticRamp *hap_ramp;
   SDL_HapticCustom *hap_custom;
   DWORD *axes;

   /* Set global stuff. */
   SDL_memset(dest, 0, sizeof(DIEFFECT));
   dest->dwSize = sizeof(DIEFFECT); /* Set the structure size. */
   dest->dwSamplePeriod = 0; /* Not used by us. */
   dest->dwGain = 10000; /* Gain is set globally, not locally. */

   /* Envelope. */
   envelope = SDL_malloc( sizeof(DIENVELOPE) );
   if (envelope == NULL) {
      SDL_OutOfMemory();
      return -1;
   }
   SDL_memset(envelope, 0, sizeof(DIENVELOPE));
   dest->lpEnvelope = envelope;
   envelope->dwSize = sizeof(DIENVELOPE); /* Always should be this. */

   /* Axes. */
   dest->cAxes = haptic->naxes;
   if (dest->cAxes > 0) {
      axes = SDL_malloc(sizeof(DWORD) * dest->cAxes);
      if (axes == NULL) {
         SDL_OutOfMemory();
         return -1;
      }
      axes[0] = DIJOFS_X; /* Always at least one axis. */
      if (dest->cAxes > 1) {
         axes[1] = DIJOFS_Y;
      }
      if (dest->cAxes > 2) {
         axes[2] = DIJOFS_Z;
      }
      dest->rgdwAxes = axes;
   }


   /* The big type handling switch, even bigger then linux's version. */
   switch (src->type) {
      case SDL_HAPTIC_CONSTANT:
         hap_constant = &src->constant;
         constant = SDL_malloc( sizeof(DICONSTANTFORCE) );
         if (constant == NULL) {
            SDL_OutOfMemory();
            return -1;
         }
         SDL_memset(constant, 0, sizeof(DICONSTANTFORCE));

         /* Specifics */
         constant->lMagnitude = CONVERT(hap_constant->level);
         dest->cbTypeSpecificParams = sizeof(DICONSTANTFORCE); 
         dest->lpvTypeSpecificParams = constant;

         /* Generics */
         dest->dwDuration = hap_constant->length * 1000; /* In microseconds. */
         dest->dwTriggerButton = DIGetTriggerButton(hap_constant->button);
         dest->dwTriggerRepeatInterval = hap_constant->interval;
         dest->dwStartDelay = hap_constant->delay * 1000; /* In microseconds. */

         /* Direction. */
         if (SDL_SYS_SetDirection(dest, &hap_constant->direction, dest->cAxes) < 0) {
            return -1;
         }
         
         /* Envelope */
         if ((hap_constant->attack_length==0) && (hap_constant->fade_length==0)) {
            SDL_free(dest->lpEnvelope);
            dest->lpEnvelope = NULL;
         }
         else {
            envelope->dwAttackLevel = CONVERT(hap_constant->attack_level);
            envelope->dwAttackTime = hap_constant->attack_length * 1000;
            envelope->dwFadeLevel = CONVERT(hap_constant->fade_level);
            envelope->dwFadeTime = hap_constant->fade_length * 1000;
         }

         break;

      case SDL_HAPTIC_SINE:
      case SDL_HAPTIC_SQUARE:
      case SDL_HAPTIC_TRIANGLE:
      case SDL_HAPTIC_SAWTOOTHUP:
      case SDL_HAPTIC_SAWTOOTHDOWN:
         hap_periodic = &src->periodic;
         periodic = SDL_malloc(sizeof(DIPERIODIC));
         if (periodic == NULL) {
            SDL_OutOfMemory();
            return -1;
         }
         SDL_memset(periodic, 0, sizeof(DIPERIODIC));

         /* Specifics */
         periodic->dwMagnitude = CONVERT(hap_periodic->magnitude);
         periodic->lOffset = CONVERT(hap_periodic->offset);
         periodic->dwPhase = hap_periodic->phase;
         periodic->dwPeriod = hap_periodic->period * 1000;
         dest->cbTypeSpecificParams = sizeof(DIPERIODIC);
         dest->lpvTypeSpecificParams = periodic;

         /* Generics */
         dest->dwDuration = hap_periodic->length * 1000; /* In microseconds. */
         dest->dwTriggerButton = DIGetTriggerButton(hap_periodic->button);
         dest->dwTriggerRepeatInterval = hap_periodic->interval;
         dest->dwStartDelay = hap_periodic->delay * 1000; /* In microseconds. */
         
         /* Direction. */
         if (SDL_SYS_SetDirection(dest, &hap_periodic->direction, dest->cAxes) < 0) {
            return -1;
         }
         
         /* Envelope */
         if ((hap_periodic->attack_length==0) && (hap_periodic->fade_length==0)) {
            SDL_free(dest->lpEnvelope);
            dest->lpEnvelope = NULL;
         }
         else {
            envelope->dwAttackLevel = CONVERT(hap_periodic->attack_level);
            envelope->dwAttackTime = hap_periodic->attack_length * 1000;
            envelope->dwFadeLevel = CONVERT(hap_periodic->fade_level);
            envelope->dwFadeTime = hap_periodic->fade_length * 1000;
         }

         break;

      case SDL_HAPTIC_SPRING:
      case SDL_HAPTIC_DAMPER:
      case SDL_HAPTIC_INERTIA:
      case SDL_HAPTIC_FRICTION:
         hap_condition = &src->condition;
         condition = SDL_malloc(sizeof(DICONDITION) * dest->cAxes);
         if (condition == NULL) {
            SDL_OutOfMemory();
            return -1;
         }
         SDL_memset(condition, 0, sizeof(DICONDITION));

         /* Specifics */
         for (i=0; i<(int)dest->cAxes; i++) {
            condition[i].lOffset = CONVERT(hap_condition->center[i]);
            condition[i].lPositiveCoefficient = CONVERT(hap_condition->right_coeff[i]);
            condition[i].lNegativeCoefficient = CONVERT(hap_condition->left_coeff[i]);
            condition[i].dwPositiveSaturation = CONVERT(hap_condition->right_sat[i]);
            condition[i].dwNegativeSaturation = CONVERT(hap_condition->left_sat[i]);
            condition[i].lDeadBand = CONVERT(hap_condition->deadband[i]);
         }
         dest->cbTypeSpecificParams = sizeof(DICONDITION) * dest->cAxes;
         dest->lpvTypeSpecificParams = condition;

         /* Generics */
         dest->dwDuration = hap_condition->length * 1000; /* In microseconds. */
         dest->dwTriggerButton = DIGetTriggerButton(hap_condition->button);
         dest->dwTriggerRepeatInterval = hap_condition->interval;
         dest->dwStartDelay = hap_condition->delay * 1000; /* In microseconds. */

         /* Direction. */
         if (SDL_SYS_SetDirection(dest, &hap_condition->direction, dest->cAxes) < 0) {
            return -1;                
         }                            
                                      
         /* Envelope */
/* TODO Check is envelope actually used.
         envelope->dwAttackLevel = CONVERT(hap_condition->attack_level);
         envelope->dwAttackTime = hap_condition->attack_length * 1000;
         envelope->dwFadeLevel = CONVERT(hap_condition->fade_level);
         envelope->dwFadeTime = hap_condition->fade_length * 1000;
*/

         break;

      case SDL_HAPTIC_RAMP:
         hap_ramp = &src->ramp;
         ramp = SDL_malloc(sizeof(DIRAMPFORCE));
         if (ramp == NULL) {
            SDL_OutOfMemory();
            return -1;
         }
         SDL_memset(ramp, 0, sizeof(DIRAMPFORCE));

         /* Specifics */
         ramp->lStart = CONVERT(hap_ramp->start);
         ramp->lEnd = CONVERT(hap_ramp->end);
         dest->cbTypeSpecificParams = sizeof(DIRAMPFORCE);
         dest->lpvTypeSpecificParams = ramp;

         /* Generics */
         dest->dwDuration = hap_ramp->length * 1000; /* In microseconds. */
         dest->dwTriggerButton = DIGetTriggerButton(hap_ramp->button);
         dest->dwTriggerRepeatInterval = hap_ramp->interval;
         dest->dwStartDelay = hap_ramp->delay * 1000; /* In microseconds. */

         /* Direction. */
         if (SDL_SYS_SetDirection(dest, &hap_ramp->direction, dest->cAxes) < 0) {
            return -1;
         }

         /* Envelope */
         if ((hap_ramp->attack_length==0) && (hap_ramp->fade_length==0)) {
            SDL_free(dest->lpEnvelope);
            dest->lpEnvelope = NULL;
         }
         else {
            envelope->dwAttackLevel = CONVERT(hap_ramp->attack_level);
            envelope->dwAttackTime = hap_ramp->attack_length * 1000;
            envelope->dwFadeLevel = CONVERT(hap_ramp->fade_level);
            envelope->dwFadeTime = hap_ramp->fade_length * 1000;
         }

         break;

      case SDL_HAPTIC_CUSTOM:
         hap_custom = &src->custom;
         custom = SDL_malloc(sizeof(DICUSTOMFORCE));
         if (custom == NULL) {
            SDL_OutOfMemory();
            return -1;
         }
         SDL_memset(custom, 0, sizeof(DICUSTOMFORCE));

         /* Specifics */
         custom->cChannels = hap_custom->channels;
         custom->dwSamplePeriod = hap_custom->period * 1000;
         custom->cSamples = hap_custom->samples;
         custom->rglForceData = SDL_malloc(sizeof(LONG)*custom->cSamples*custom->cChannels);
         for (i=0; i<hap_custom->samples*hap_custom->channels; i++) { /* Copy data. */
            custom->rglForceData[i] = CONVERT(hap_custom->data[i]);
         }
         dest->cbTypeSpecificParams = sizeof(DICUSTOMFORCE);
         dest->lpvTypeSpecificParams = custom;

         /* Generics */
         dest->dwDuration = hap_custom->length * 1000; /* In microseconds. */
         dest->dwTriggerButton = DIGetTriggerButton(hap_custom->button);
         dest->dwTriggerRepeatInterval = hap_custom->interval;
         dest->dwStartDelay = hap_custom->delay * 1000; /* In microseconds. */

         /* Direction. */
         if (SDL_SYS_SetDirection(dest, &hap_custom->direction, dest->cAxes) < 0) {
            return -1;
         }
         
         /* Envelope */
         if ((hap_custom->attack_length==0) && (hap_custom->fade_length==0)) {
            SDL_free(dest->lpEnvelope);
            dest->lpEnvelope = NULL;
         }
         else {
            envelope->dwAttackLevel = CONVERT(hap_custom->attack_level);
            envelope->dwAttackTime = hap_custom->attack_length * 1000;
            envelope->dwFadeLevel = CONVERT(hap_custom->fade_level);
            envelope->dwFadeTime = hap_custom->fade_length * 1000;
         }

         break;


      default:
         SDL_SetError("Haptic: Unknown effect type.");
         return -1;
   }

   return 0;
}


/*
 * Frees an DIEFFECT allocated by SDL_SYS_ToDIEFFECT.
 */
static void
SDL_SYS_HapticFreeDIEFFECT( DIEFFECT * effect, int type )
{
   DICUSTOMFORCE *custom;

   if (effect->lpEnvelope != NULL) {
      SDL_free(effect->lpEnvelope);
      effect->lpEnvelope = NULL;
   }
   if (effect->rgdwAxes != NULL) {
      SDL_free(effect->rgdwAxes);
      effect->rgdwAxes = NULL;
   }
   if (effect->lpvTypeSpecificParams != NULL) {
      if (type == SDL_HAPTIC_CUSTOM) { /* Must free the custom data. */
         custom = (DICUSTOMFORCE*) effect->lpvTypeSpecificParams;
         SDL_free(custom->rglForceData);
         custom->rglForceData = NULL;
      }
      SDL_free(effect->lpvTypeSpecificParams);
      effect->lpvTypeSpecificParams = NULL;
   }
   if (effect->rglDirection != NULL) {
      SDL_free(effect->rglDirection);
      effect->rglDirection = NULL;
   }
}


/*
 * Gets the effect type from the generic SDL haptic effect wrapper.
 */
REFGUID
SDL_SYS_HapticEffectType(struct haptic_effect * effect)
{
   switch (effect->effect.type) {
      case SDL_HAPTIC_CONSTANT:
         return &GUID_ConstantForce;

      case SDL_HAPTIC_RAMP:
         return &GUID_RampForce;

      case SDL_HAPTIC_SQUARE:
         return &GUID_Square;

      case SDL_HAPTIC_SINE:
         return &GUID_Sine;

      case SDL_HAPTIC_TRIANGLE:
         return &GUID_Triangle;

      case SDL_HAPTIC_SAWTOOTHUP:
         return &GUID_SawtoothUp;

      case SDL_HAPTIC_SAWTOOTHDOWN:
         return &GUID_SawtoothDown;

      case SDL_HAPTIC_SPRING:
         return &GUID_Spring;

      case SDL_HAPTIC_DAMPER:
         return &GUID_Damper;

      case SDL_HAPTIC_INERTIA:
         return &GUID_Inertia;

      case SDL_HAPTIC_FRICTION:
         return &GUID_Friction;

      case SDL_HAPTIC_CUSTOM:
         return &GUID_CustomForce;

      default:
         SDL_SetError("Haptic: Unknown effect type.");
         return NULL;
   }
}


/*
 * Creates a new haptic effect.
 */
int
SDL_SYS_HapticNewEffect(SDL_Haptic * haptic, struct haptic_effect * effect,
      SDL_HapticEffect * base)
{
   HRESULT ret;

   /* Get the type. */
   REFGUID type = SDL_SYS_HapticEffectType(effect);
   if (type == NULL) {
      goto err_hweffect;
   }

   /* Alloc the effect. */
   effect->hweffect = (struct haptic_hweffect *)
         SDL_malloc(sizeof(struct haptic_hweffect));
   if (effect->hweffect == NULL) {
      SDL_OutOfMemory();
      goto err_hweffect;
   }

   /* Get the effect. */
   if (SDL_SYS_ToDIEFFECT(haptic, &effect->hweffect->effect, base) < 0) {
      goto err_effectdone;
   }

   /* Create the actual effect. */
   ret = IDirectInputDevice2_CreateEffect(haptic->hwdata->device, type,
         &effect->hweffect->effect, &effect->hweffect->ref, NULL);
   if (FAILED(ret)) {
      DI_SetError("Unable to create effect",ret);
      goto err_effectdone;
   }

   return 0;

err_effectdone:
   SDL_SYS_HapticFreeDIEFFECT(&effect->hweffect->effect, base->type);
err_hweffect:
   if (effect->hweffect != NULL) {
      SDL_free(effect->hweffect);
      effect->hweffect = NULL;
   }
   return -1;
}


/*
 * Updates an effect.
 */
int
SDL_SYS_HapticUpdateEffect(SDL_Haptic * haptic,
      struct haptic_effect * effect, SDL_HapticEffect * data)
{
   HRESULT ret;
   DWORD flags;
   DIEFFECT temp;

   /* Get the effect. */
   SDL_memset(&temp, 0, sizeof(DIEFFECT));
   if (SDL_SYS_ToDIEFFECT(haptic, &temp, data) < 0) {
      goto err_update;
   }

   /* Set the flags.  Might be worthwhile to diff temp with loaded effect and
    *  only change those parameters. */
   flags = DIEP_DIRECTION | 
           DIEP_DURATION |
           DIEP_ENVELOPE |
           DIEP_STARTDELAY |
           DIEP_TRIGGERBUTTON |
           DIEP_TRIGGERREPEATINTERVAL |
           DIEP_TYPESPECIFICPARAMS;

   /* Create the actual effect. */
   ret = IDirectInputEffect_SetParameters(effect->hweffect->ref, &temp, flags);
   if (FAILED(ret)) {
      DI_SetError("Unable to update effect",ret);
      goto err_update;
   }

   /* Copy it over. */
   SDL_SYS_HapticFreeDIEFFECT(&effect->hweffect->effect, data->type);
   SDL_memcpy(&effect->hweffect->effect, &temp, sizeof(DIEFFECT));

   return 0;

err_update:
   SDL_SYS_HapticFreeDIEFFECT(&temp, data->type);
   return -1;
}


/*
 * Runs an effect.
 */
int
SDL_SYS_HapticRunEffect(SDL_Haptic * haptic, struct haptic_effect * effect,
                        Uint32 iterations)
{
   HRESULT ret;
   DWORD iter;

   /* Check if it's infinite. */
   if (iterations == SDL_HAPTIC_INFINITY) {
      iter = INFINITE;
   }
   else
      iter = iterations;

   /* Run the effect. */
   ret = IDirectInputEffect_Start( effect->hweffect->ref, iter, 0 );
   if (FAILED(ret)) {
      DI_SetError("Running the effect",ret);
      return -1;
   }

   return 0;
}


/*
 * Stops an effect.
 */
int
SDL_SYS_HapticStopEffect(SDL_Haptic * haptic, struct haptic_effect * effect)
{
   HRESULT ret;

   ret = IDirectInputEffect_Stop(effect->hweffect->ref);
   if (FAILED(ret)) {
      DI_SetError("Unable to stop effect",ret);
      return -1;
   }

   return 0;
}


/*
 * Frees the effect.
 */
void
SDL_SYS_HapticDestroyEffect(SDL_Haptic * haptic, struct haptic_effect * effect)
{
   HRESULT ret;

   ret = IDirectInputEffect_Unload(effect->hweffect->ref);
   if (FAILED(ret)) {
      DI_SetError("Removing effect from the device",ret);
   }
   SDL_SYS_HapticFreeDIEFFECT(&effect->hweffect->effect, effect->effect.type);   
   SDL_free(effect->hweffect);
   effect->hweffect = NULL;
}


/*
 * Gets the status of a haptic effect.
 */
int
SDL_SYS_HapticGetEffectStatus(SDL_Haptic * haptic, struct haptic_effect * effect)
{
   SDL_SetError("Haptic: Status not supported.");
   return -1;
}


/*
 * Sets the gain.
 */
int
SDL_SYS_HapticSetGain(SDL_Haptic * haptic, int gain)
{
   HRESULT ret;
   DIPROPDWORD dipdw;

   /* Create the weird structure thingy. */
   dipdw.diph.dwSize       = sizeof(DIPROPDWORD);
   dipdw.diph.dwHeaderSize = sizeof(DIPROPHEADER);
   dipdw.diph.dwObj        = 0;
   dipdw.diph.dwHow        = DIPH_DEVICE;
   dipdw.dwData            = gain * 100; /* 0 to 10,000 */

   /* Try to set the autocenter. */
   ret = IDirectInputDevice2_SetProperty( haptic->hwdata->device,
                                          DIPROP_FFGAIN, &dipdw.diph );
   if (FAILED(ret)) {
      DI_SetError("Setting gain",ret);
      return -1;
   }
  
   return 0;
}


/*
 * Sets the autocentering.
 */
int
SDL_SYS_HapticSetAutocenter(SDL_Haptic * haptic, int autocenter)
{
   HRESULT ret;
   DIPROPDWORD dipdw;

   /* Create the weird structure thingy. */
   dipdw.diph.dwSize       = sizeof(DIPROPDWORD);
   dipdw.diph.dwHeaderSize = sizeof(DIPROPHEADER);
   dipdw.diph.dwObj        = 0;
   dipdw.diph.dwHow        = DIPH_DEVICE;
   dipdw.dwData            = (autocenter == 0) ? DIPROPAUTOCENTER_OFF : 
                                                 DIPROPAUTOCENTER_ON;

   /* Try to set the autocenter. */
   ret = IDirectInputDevice2_SetProperty( haptic->hwdata->device,
                                          DIPROP_AUTOCENTER, &dipdw.diph );
   if (FAILED(ret)) {
      DI_SetError("Setting autocenter",ret);
      return -1;
   }
  
   return 0;

}


#endif /* SDL_HAPTIC_DINPUT */