idz, idac, swdc: added FFB centering spring feature

swdcio/config.c

@@ -67,6 +67,14 @@ void swdc_di_config_load(struct swdc_di_config *cfg, const wchar_t *filename)
                             L"reverseAccelAxis",
                             0,
                             filename);
+
+    // FFB configuration
+
+    cfg->center_spring_strength = GetPrivateProfileIntW(
+                            L"dinput",
+                            L"centerSpringStrength",
+                            30,
+                            filename);
 }
 
 void swdc_xi_config_load(struct swdc_xi_config *cfg, const wchar_t *filename)

swdcio/config.h

@@ -19,6 +19,9 @@ struct swdc_di_config {
     uint8_t wheel_yellow;
     bool reverse_brake_axis;
     bool reverse_accel_axis;
+
+    // FFB configuration
+    uint16_t center_spring_strength;
 };
 
 struct swdc_xi_config {

swdcio/di-dev.c

@@ -44,7 +44,8 @@ HRESULT swdc_di_dev_start(IDirectInputDevice8W *dev, HWND wnd)
     return hr;
 }
 
-void swdc_di_dev_start_fx(IDirectInputDevice8W *dev, IDirectInputEffect **out)
+void swdc_di_dev_start_fx(
+    IDirectInputDevice8W *dev, IDirectInputEffect **out, uint16_t strength)
 {
     /* Set up force-feedback on devices that support it. This is just a stub
        for the time being, since we don't yet know how the serial port force
@@ -67,7 +68,7 @@ void swdc_di_dev_start_fx(IDirectInputDevice8W *dev, IDirectInputEffect **out)
     DWORD axis;
     LONG direction;
     DIEFFECT fx;
-    DICONSTANTFORCE cf;
+    DICONDITION cond;
     HRESULT hr;
 
     assert(dev != NULL);
@@ -77,11 +78,17 @@ void swdc_di_dev_start_fx(IDirectInputDevice8W *dev, IDirectInputEffect **out)
 
     dprintf("DirectInput: Starting force feedback (may take a sec)\n");
 
+    // Auto-centering effect
     axis = DIJOFS_X;
     direction = 0;
 
-    memset(&cf, 0, sizeof(cf));
-    cf.lMagnitude = 0;
+    memset(&cond, 0, sizeof(cond));
+    cond.lOffset = 0;
+    cond.lPositiveCoefficient = strength;
+    cond.lNegativeCoefficient = strength;
+    cond.dwPositiveSaturation = strength; // For FG920?
+    cond.dwNegativeSaturation = strength; // For FG920?
+    cond.lDeadBand = 0;
 
     memset(&fx, 0, sizeof(fx));
     fx.dwSize = sizeof(fx);
@@ -93,20 +100,19 @@ void swdc_di_dev_start_fx(IDirectInputDevice8W *dev, IDirectInputEffect **out)
     fx.cAxes = 1;
     fx.rgdwAxes = &axis;
     fx.rglDirection = &direction;
-    fx.cbTypeSpecificParams = sizeof(cf);
-    fx.lpvTypeSpecificParams = &cf;
+    fx.cbTypeSpecificParams = sizeof(cond);
+    fx.lpvTypeSpecificParams = &cond;
 
     hr = IDirectInputDevice8_CreateEffect(
             dev,
-            &GUID_ConstantForce,
+            &GUID_Spring,
             &fx,
             &obj,
             NULL);
 
     if (FAILED(hr)) {
-        dprintf("DirectInput: DirectInput force feedback unavailable: %08x\n",
+        dprintf("DirectInput: Centering spring force feedback unavailable: %08x\n",
                 (int) hr);
-
         return;
     }
 
@@ -114,15 +120,15 @@ void swdc_di_dev_start_fx(IDirectInputDevice8W *dev, IDirectInputEffect **out)
 
     if (FAILED(hr)) {
         IDirectInputEffect_Release(obj);
-        dprintf("DirectInput: DirectInput force feedback start failed: %08x\n",
+        dprintf("DirectInput: Centering spring force feedback start failed: %08x\n",
                 (int) hr);
-
         return;
     }
 
     *out = obj;
 
-    dprintf("DirectInput: Force feedback initialized and set to zero\n");
+    dprintf("DirectInput: Centering spring effects initialized with strength %d%%\n", 
+            strength / 100);
 }
 
 HRESULT swdc_di_dev_poll(

swdcio/di-dev.h

@@ -11,7 +11,7 @@ union swdc_di_state {
 };
 
 HRESULT swdc_di_dev_start(IDirectInputDevice8W *dev, HWND wnd);
-void swdc_di_dev_start_fx(IDirectInputDevice8W *dev, IDirectInputEffect **out);
+void swdc_di_dev_start_fx(IDirectInputDevice8W *dev, IDirectInputEffect **out, uint16_t strength);
 HRESULT swdc_di_dev_poll(
         IDirectInputDevice8W *dev,
         HWND wnd,

swdcio/di.c

@@ -70,6 +70,7 @@ static uint8_t swdc_di_wheel_yellow;
 static bool swdc_di_use_pedals;
 static bool swdc_di_reverse_brake_axis;
 static bool swdc_di_reverse_accel_axis;
+static uint16_t swdc_di_center_spring_strength;
 
 HRESULT swdc_di_init(
         const struct swdc_di_config *cfg,
@@ -168,7 +169,9 @@ HRESULT swdc_di_init(
         return hr;
     }
 
-    swdc_di_dev_start_fx(swdc_di_dev, &swdc_di_fx);
+    // Convert the strength from 0-100 to 0-10000 for DirectInput
+    swdc_di_dev_start_fx(swdc_di_dev, &swdc_di_fx,
+                         swdc_di_center_spring_strength * 100);
 
     if (cfg->pedals_name[0] != L'\0') {
         hr = IDirectInput8_EnumDevices(
@@ -320,6 +323,16 @@ static HRESULT swdc_di_config_apply(const struct swdc_di_config *cfg)
     swdc_di_reverse_brake_axis = cfg->reverse_brake_axis;
     swdc_di_reverse_accel_axis = cfg->reverse_accel_axis;
 
+    // FFB configuration
+
+    if (cfg->center_spring_strength < 0 || cfg->center_spring_strength > 100) {
+        dprintf("Wheel: Invalid center spring strength: %i\n", cfg->center_spring_strength);
+
+        return E_INVALIDARG;
+    }
+
+    swdc_di_center_spring_strength = cfg->center_spring_strength;
+
     return S_OK;
 }