idac, idz, swdc: Fixed DInput brake/accel, added cubic steering

dist/idac/segatools.ini

@@ -65,6 +65,18 @@ path=
 ; Leave empty if you want to use Segatools built-in gamepad/wheel input.
 path=
 
+; -----------------------------------------------------------------------------
+; Input settings
+; -----------------------------------------------------------------------------
+
+; Keyboard bindings are specified as hexadecimal (prefixed with 0x) or decimal
+; (not prefixed with 0x) virtual-key codes, a list of which can be found here:
+;
+; https://docs.microsoft.com/en-us/windows/win32/inputdev/virtual-key-codes
+;
+; This is, admittedly, not the most user-friendly configuration method in the
+; world. An improved solution will be provided later.
+
 [io4]
 ; Test button virtual-key code. Default is the 1 key.
 test=0x31
@@ -72,6 +84,7 @@ test=0x31
 service=0x32
 ; Keyboard button to increment coin counter. Default is the 3 key.
 coin=0x33
+
 ; Input API selection for IO4 input emulator.
 ; Set "xinput" to use a gamepad and "dinput" to use a steering wheel.
 mode=xinput
@@ -79,20 +92,22 @@ mode=xinput
 ; pressed (e.g. when navigating menus between races).
 autoNeutral=1
 ; Use the left thumbstick for steering instead of both on XInput Controllers.
-; Not recommended as it will not give you the precision needed for this game
+; Not recommended as it will not give you the precision needed for this game.
 singleStickSteering=1
+; Use linear steering instead of the default non-linear cubing steering.
+linearSteering=0
 ; Adjust scaling for steering wheel input.
 ;
 ; This setting scales the steering wheel input so that the maximum positive
 ; and minimum negative steering inputs reported in the operator menu's input
 ; test screen do not exceed the value below. The maximum possible value is 128,
-; and the value that matches the input range of a real cabinet is 97.
+; and the value that matches the input range of a real cabinet is 128.
 ;
 ; NOTE: This is not the same thing as DirectInput steering wheel movement
 ; range! Segatools cannot control the maximum angle of your physical steering
 ; wheel controller, this setting is vendor-specific and can only be adjusted
 ; in the Control Panel.
-restrict=97
+restrict=128
 
 [dinput]
 ; Name of the DirectInput wheel to use (or any text that occurs in its name)

dist/idz/segatools.ini

@@ -8,6 +8,11 @@ option=
 ; NOTE: This has nothing to do with Windows %APPDATA%.
 appdata=
 
+[aime]
+; Controls emulation of the Aime card reader assembly.
+enable=1
+aimePath=DEVICE\aime.txt
+
 [dns]
 ; Insert the hostname or IP address of the server you wish to use here.
 ; Note that 127.0.0.1, localhost etc are specifically rejected.
@@ -50,7 +55,26 @@ path=
 ; Leave empty if you want to use Segatools built-in gamepad/wheel input.
 path=
 
+; -----------------------------------------------------------------------------
+; Input settings
+; -----------------------------------------------------------------------------
+
+; Keyboard bindings are specified as hexadecimal (prefixed with 0x) or decimal
+; (not prefixed with 0x) virtual-key codes, a list of which can be found here:
+;
+; https://docs.microsoft.com/en-us/windows/win32/inputdev/virtual-key-codes
+;
+; This is, admittedly, not the most user-friendly configuration method in the
+; world. An improved solution will be provided later.
+
 [io3]
+; Test button virtual-key code. Default is the 1 key.
+test=0x31
+; Service button virtual-key code. Default is the 2 key.
+service=0x32
+; Keyboard button to increment coin counter. Default is the 3 key.
+coin=0x33
+
 ; Input API selection for JVS input emulator.
 ; Set "xinput" to use a gamepad and "dinput" to use a steering wheel.
 mode=xinput
@@ -58,8 +82,10 @@ mode=xinput
 ; pressed (e.g. when navigating menus between races).
 autoNeutral=1
 ; Use the left thumbstick for steering instead of both on XInput Controllers.
-; Not recommended as it will not give you the precision needed for this game
+; Not recommended as it will not give you the precision needed for this game.
-singleStickSteering=0
+singleStickSteering=1
+; Use linear steering instead of the default non-linear cubing steering.
+linearSteering=0
 ; Adjust scaling for steering wheel input.
 ;
 ; This setting scales the steering wheel input so that the maximum positive

dist/swdc/segatools.ini

@@ -40,6 +40,18 @@ path=
 ; Leave empty if you want to use Segatools built-in gamepad/wheel input.
 path=
 
+; -----------------------------------------------------------------------------
+; Input settings
+; -----------------------------------------------------------------------------
+
+; Keyboard bindings are specified as hexadecimal (prefixed with 0x) or decimal
+; (not prefixed with 0x) virtual-key codes, a list of which can be found here:
+;
+; https://docs.microsoft.com/en-us/windows/win32/inputdev/virtual-key-codes
+;
+; This is, admittedly, not the most user-friendly configuration method in the
+; world. An improved solution will be provided later.
+
 [io4]
 ; Test button virtual-key code. Default is the 1 key.
 test=0x31
@@ -49,22 +61,25 @@ service=0x32
 coin=0x33
 ; Input API selection for IO4 input emulator.
 ; Set "xinput" to use a gamepad and "dinput" to use a steering wheel.
+
 mode=xinput
 ; Use the left thumbstick for steering instead of both on XInput Controllers.
-; Not recommended as it will not give you the precision needed for this game
+; Not recommended as it will not give you the precision needed for this game.
 singleStickSteering=1
+; Use linear steering instead of the default non-linear cubing steering.
+linearSteering=0
 ; Adjust scaling for steering wheel input.
 ;
 ; This setting scales the steering wheel input so that the maximum positive
 ; and minimum negative steering inputs reported in the operator menu's input
 ; test screen do not exceed the value below. The maximum possible value is 128,
-; and the value that matches the input range of a real cabinet is 97.
+; and the value that matches the input range of a real cabinet is 128.
 ;
 ; NOTE: This is not the same thing as DirectInput steering wheel movement
 ; range! Segatools cannot control the maximum angle of your physical steering
 ; wheel controller, this setting is vendor-specific and can only be adjusted
 ; in the Control Panel.
-restrict=97
+restrict=128
 
 [dinput]
 ; Name of the DirectInput wheel to use (or any text that occurs in its name)

idachook/dllmain.c

@@ -75,7 +75,7 @@ static DWORD CALLBACK idac_pre_startup(void)
 
     spike_hook_init(L".\\segatools.ini");
 
-    dprintf("--- End idac_pre_startup ---\n");
+    dprintf("---  End  idac_pre_startup ---\n");
 
     /* Jump to EXE start address */
 

idacio/config.c

@@ -81,6 +81,12 @@ void idac_xi_config_load(struct idac_xi_config *cfg, const wchar_t *filename)
                                 L"singleStickSteering",
                                 0,
                                 filename);
+
+    cfg->linear_steering = GetPrivateProfileIntW(
+                           L"io4",
+                           L"linearSteering",
+                           0,
+                           filename);
 }
 
 void idac_io_config_load(struct idac_io_config *cfg, const wchar_t *filename)

idacio/config.h

@@ -24,6 +24,7 @@ struct idac_di_config {
 
 struct idac_xi_config {
     bool single_stick_steering;
+    bool linear_steering;
 };
 
 struct idac_io_config {

idacio/di.c

@@ -262,8 +262,8 @@ static HRESULT idac_di_config_apply(const struct idac_di_config *cfg)
     dprintf("Wheel: --- Begin configuration ---\n");
     dprintf("Wheel: Device name . . . . : Contains \"%S\"\n",
             cfg->device_name);
-    dprintf("Wheel: Brake axis  . . . . : %S\n", accel_axis->name);
+    dprintf("Wheel: Brake axis  . . . . : %S\n", brake_axis->name);
-    dprintf("Wheel: Accelerator axis  . : %S\n", brake_axis->name);
+    dprintf("Wheel: Accel axis  . . . . : %S\n", accel_axis->name);
     dprintf("Wheel: Start button  . . . : %i\n", cfg->start);
     dprintf("Wheel: View Change button  : %i\n", cfg->view_chg);
     dprintf("Wheel: Shift Down button . : %i\n", cfg->shift_dn);
@@ -286,8 +286,8 @@ static HRESULT idac_di_config_apply(const struct idac_di_config *cfg)
         dprintf("Shifter: ---  End  configuration ---\n");
     }
 
-    idac_di_off_brake = accel_axis->off;
+    idac_di_off_brake = brake_axis->off;
-    idac_di_off_accel = brake_axis->off;
+    idac_di_off_accel = accel_axis->off;
     idac_di_start = cfg->start;
     idac_di_view_chg = cfg->view_chg;
     idac_di_shift_dn = cfg->shift_dn;

idacio/xi.c

@@ -1,16 +1,16 @@
-#include <windows.h>
+#include "idacio/xi.h"
-#include <xinput.h>
 
 #include <assert.h>
+#include <math.h>
 #include <stdbool.h>
 #include <stdint.h>
+#include <windows.h>
+#include <xinput.h>
 
 #include "idacio/backend.h"
 #include "idacio/config.h"
 #include "idacio/idacio.h"
 #include "idacio/shifter.h"
-#include "idacio/xi.h"
-
 #include "util/dprintf.h"
 
 static void idac_xi_get_gamebtns(uint8_t *gamebtn_out);
@@ -20,15 +20,15 @@ static void idac_xi_get_analogs(struct idac_io_analog_state *out);
 static HRESULT idac_xi_config_apply(const struct idac_xi_config *cfg);
 
 static const struct idac_io_backend idac_xi_backend = {
-    .get_gamebtns  = idac_xi_get_gamebtns,
+    .get_gamebtns = idac_xi_get_gamebtns,
-    .get_shifter   = idac_xi_get_shifter,
+    .get_shifter = idac_xi_get_shifter,
-    .get_analogs   = idac_xi_get_analogs,
+    .get_analogs = idac_xi_get_analogs,
 };
 
 static bool idac_xi_single_stick_steering;
+static bool idac_xi_linear_steering;
 
-HRESULT idac_xi_init(const struct idac_xi_config *cfg, const struct idac_io_backend **backend)
+HRESULT idac_xi_init(const struct idac_xi_config *cfg, const struct idac_io_backend **backend) {
-{
     HRESULT hr;
     assert(cfg != NULL);
     assert(backend != NULL);
@@ -45,24 +45,23 @@ HRESULT idac_xi_init(const struct idac_xi_config *cfg, const struct idac_io_back
     return S_OK;
 }
 
-HRESULT idac_io_poll(void)
+HRESULT idac_io_poll(void) {
-{    
     return S_OK;
 }
 
-static HRESULT idac_xi_config_apply(const struct idac_xi_config *cfg)
+static HRESULT idac_xi_config_apply(const struct idac_xi_config *cfg) {
-{
     dprintf("XInput: --- Begin configuration ---\n");
     dprintf("XInput: Single Stick Steering : %i\n", cfg->single_stick_steering);
+    dprintf("XInput: Linear Steering . . . : %i\n", cfg->linear_steering);
     dprintf("XInput: ---  End  configuration ---\n");
 
     idac_xi_single_stick_steering = cfg->single_stick_steering;
+    idac_xi_linear_steering = cfg->linear_steering;
 
     return S_OK;
 }
 
-static void idac_xi_get_gamebtns(uint8_t *gamebtn_out)
+static void idac_xi_get_gamebtns(uint8_t *gamebtn_out) {
-{
     uint8_t gamebtn;
     XINPUT_STATE xi;
     WORD xb;
@@ -102,8 +101,7 @@ static void idac_xi_get_gamebtns(uint8_t *gamebtn_out)
     *gamebtn_out = gamebtn;
 }
 
-static void idac_xi_get_shifter(uint8_t *gear)
+static void idac_xi_get_shifter(uint8_t *gear) {
-{
     bool shift_dn;
     bool shift_up;
     XINPUT_STATE xi;
@@ -144,8 +142,32 @@ static void idac_xi_get_shifter(uint8_t *gear)
     *gear = idac_shifter_current_gear();
 }
 
-static void idac_xi_get_analogs(struct idac_io_analog_state *out)
+static int apply_non_linear_transform(int value, int deadzone_center) {
-{
+    const int max_input = 32767;
+    const double power_factor = 3.0;
+
+    // Apply deadzone only after passing the center threshold
+    if (abs(value) < deadzone_center) {
+        return 0;
+    }
+
+    // Scale the value to the range [-1.0, 1.0]
+    double scaled_value = (abs(value) - deadzone_center) / (double)(max_input - deadzone_center);
+
+    // Apply a non-linear transform (cubing in this case) and preserve the sign
+    double signed_value = copysign(pow(scaled_value, power_factor), value);
+
+    // Scale the value back to the range [-32770, 32767]
+    int transformed_value = (int)(signed_value * max_input);
+
+    // Clamp the value to the range [-32767, 32767]
+    transformed_value = (transformed_value > max_input) ? max_input : transformed_value;
+    transformed_value = (transformed_value < -max_input) ? -max_input : transformed_value;
+
+    return transformed_value;
+}
+
+static void idac_xi_get_analogs(struct idac_io_analog_state *out) {
     XINPUT_STATE xi;
     int left;
     int right;
@@ -156,27 +178,33 @@ static void idac_xi_get_analogs(struct idac_io_analog_state *out)
     XInputGetState(0, &xi);
 
     left = xi.Gamepad.sThumbLX;
-
-    if (left < -XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
-        left += XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
-    } else if (left > XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
-        left -= XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
-    } else {
-        left = 0;
-    }
-
     right = xi.Gamepad.sThumbRX;
 
-    if (right < -XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+    if (!idac_xi_linear_steering) {
-        right += XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        // Apply non-linear transform for both sticks
-    } else if (right > XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+        left = apply_non_linear_transform(left, XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE);
-        right -= XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        right = apply_non_linear_transform(right, XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE);
     } else {
-        right = 0;
+        if (left < -XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
+            left += XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
+        } else if (left > XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
+            left -= XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
+        } else {
+            left = 0;
+        }
+
+        if (right < -XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+            right += XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        } else if (right > XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+            right -= XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        } else {
+            right = 0;
+        }
     }
 
     if (idac_xi_single_stick_steering) {
         out->wheel = left;
+        // dprintf("XInput: Single Stick Steering: %i\n", out->wheel);
     } else {
         out->wheel = (left + right) / 2;
     }

idzhook/dllmain.c

@@ -107,7 +107,7 @@ static DWORD CALLBACK idz_pre_startup(void)
 
     spike_hook_init(L".\\segatools.ini");
 
-    dprintf("--- End idz_pre_startup ---\n");
+    dprintf("---  End  idz_pre_startup ---\n");
 
     /* Jump to EXE start address */
 

idzio/config.c

@@ -81,6 +81,12 @@ void idz_xi_config_load(struct idz_xi_config *cfg, const wchar_t *filename)
                                 L"singleStickSteering",
                                 0,
                                 filename);
+
+    cfg->linear_steering = GetPrivateProfileIntW(
+                           L"io3",
+                           L"linearSteering",
+                           0,
+                           filename);
 }
 
 void idz_io_config_load(struct idz_io_config *cfg, const wchar_t *filename)

idzio/config.h

@@ -24,6 +24,7 @@ struct idz_di_config {
 
 struct idz_xi_config {
     bool single_stick_steering;
+    bool linear_steering;
 };
 
 struct idz_io_config {

idzio/di.c

@@ -262,8 +262,8 @@ static HRESULT idz_di_config_apply(const struct idz_di_config *cfg)
     dprintf("Wheel: --- Begin configuration ---\n");
     dprintf("Wheel: Device name . . . . : Contains \"%S\"\n",
             cfg->device_name);
-    dprintf("Wheel: Brake axis  . . . . : %S\n", accel_axis->name);
+    dprintf("Wheel: Brake axis  . . . . : %S\n", brake_axis->name);
-    dprintf("Wheel: Accelerator axis  . : %S\n", brake_axis->name);
+    dprintf("Wheel: Accel axis  . . . . : %S\n", accel_axis->name);
     dprintf("Wheel: Start button  . . . : %i\n", cfg->start);
     dprintf("Wheel: View Change button  : %i\n", cfg->view_chg);
     dprintf("Wheel: Shift Down button . : %i\n", cfg->shift_dn);
@@ -286,8 +286,8 @@ static HRESULT idz_di_config_apply(const struct idz_di_config *cfg)
         dprintf("Shifter: ---  End  configuration ---\n");
     }
 
-    idz_di_off_brake = accel_axis->off;
+    idz_di_off_brake = brake_axis->off;
-    idz_di_off_accel = brake_axis->off;
+    idz_di_off_accel = accel_axis->off;
     idz_di_start = cfg->start;
     idz_di_view_chg = cfg->view_chg;
     idz_di_shift_dn = cfg->shift_dn;

idzio/xi.c

@@ -1,6 +1,7 @@
 #include <windows.h>
 #include <xinput.h>
 
+#include <math.h>
 #include <assert.h>
 #include <stdbool.h>
 #include <stdint.h>
@@ -26,6 +27,7 @@ static const struct idz_io_backend idz_xi_backend = {
 };
 
 static bool idz_xi_single_stick_steering;
+static bool idz_xi_linear_steering;
 
 HRESULT idz_xi_init(const struct idz_xi_config *cfg, const struct idz_io_backend **backend)
 {
@@ -49,9 +51,11 @@ static HRESULT idz_xi_config_apply(const struct idz_xi_config *cfg)
 {
     dprintf("XInput: --- Begin configuration ---\n");
     dprintf("XInput: Single Stick Steering : %i\n", cfg->single_stick_steering);
+    dprintf("XInput: Linear Steering . . . : %i\n", cfg->linear_steering);
     dprintf("XInput: ---  End  configuration ---\n");
 
     idz_xi_single_stick_steering = cfg->single_stick_steering;
+    idz_xi_linear_steering = cfg->linear_steering;
 
     return S_OK;
 }
@@ -123,6 +127,31 @@ static void idz_xi_jvs_read_shifter(uint8_t *gear)
     *gear = idz_shifter_current_gear();
 }
 
+static int apply_non_linear_transform(int value, int deadzone_center) {
+    const int max_input = 32767;
+    const double power_factor = 3.0;
+
+    // Apply deadzone only after passing the center threshold
+    if (abs(value) < deadzone_center) {
+        return 0;
+    }
+
+    // Scale the value to the range [-1.0, 1.0]
+    double scaled_value = (abs(value) - deadzone_center) / (double)(max_input - deadzone_center);
+
+    // Apply a non-linear transform (cubing in this case) and preserve the sign
+    double signed_value = copysign(pow(scaled_value, power_factor), value);
+
+    // Scale the value back to the range [-32770, 32767]
+    int transformed_value = (int)(signed_value * max_input);
+
+    // Clamp the value to the range [-32767, 32767]
+    transformed_value = (transformed_value > max_input) ? max_input : transformed_value;
+    transformed_value = (transformed_value < -max_input) ? -max_input : transformed_value;
+
+    return transformed_value;
+}
+
 static void idz_xi_jvs_read_analogs(struct idz_io_analog_state *out)
 {
     XINPUT_STATE xi;
@@ -135,23 +164,28 @@ static void idz_xi_jvs_read_analogs(struct idz_io_analog_state *out)
     XInputGetState(0, &xi);
 
     left = xi.Gamepad.sThumbLX;
-
-    if (left < -XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
-        left += XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
-    } else if (left > XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
-        left -= XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
-    } else {
-        left = 0;
-    }
-
     right = xi.Gamepad.sThumbRX;
-
+    
-    if (right < -XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+    if (!idz_xi_linear_steering) {
-        right += XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        // Apply non-linear transform for both sticks
-    } else if (right > XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+        left = apply_non_linear_transform(left, XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE);
-        right -= XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        right = apply_non_linear_transform(right, XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE);
     } else {
-        right = 0;
+        if (left < -XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
+            left += XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
+        } else if (left > XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
+            left -= XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
+        } else {
+            left = 0;
+        }
+
+        if (right < -XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+            right += XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        } else if (right > XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+            right -= XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        } else {
+            right = 0;
+        }
     }
 
     if(idz_xi_single_stick_steering) {

swdcio/config.c

@@ -71,6 +71,12 @@ void swdc_xi_config_load(struct swdc_xi_config *cfg, const wchar_t *filename)
                                 L"singleStickSteering",
                                 0,
                                 filename);
+
+    cfg->linear_steering = GetPrivateProfileIntW(
+                           L"io4",
+                           L"linearSteering",
+                           0,
+                           filename);
 }
 
 void swdc_io_config_load(struct swdc_io_config *cfg, const wchar_t *filename)

swdcio/config.h

@@ -26,6 +26,7 @@ struct swdc_di_config {
 
 struct swdc_xi_config {
     bool single_stick_steering;
+    bool linear_steering;
 };
 
 struct swdc_io_config {

swdcio/di.c

@@ -246,8 +246,8 @@ static HRESULT swdc_di_config_apply(const struct swdc_di_config *cfg)
     dprintf("Wheel: --- Begin configuration ---\n");
     dprintf("Wheel: Device name . . . . : Contains \"%S\"\n",
             cfg->device_name);
-    dprintf("Wheel: Brake axis . . . . . . : %S\n", accel_axis->name);
+    dprintf("Wheel: Brake axis . . . . . . : %S\n", brake_axis->name);
-    dprintf("Wheel: Accelerator axis . . . : %S\n", brake_axis->name);
+    dprintf("Wheel: Accel axis . . . . . . : %S\n", accel_axis->name);
     dprintf("Wheel: Start button . . . . . : %i\n", cfg->start);
     dprintf("Wheel: View Change button . . : %i\n", cfg->view_chg);
     dprintf("Wheel: Shift Down button  . . : %i\n", cfg->shift_dn);
@@ -260,8 +260,8 @@ static HRESULT swdc_di_config_apply(const struct swdc_di_config *cfg)
     dprintf("Wheel: Reverse Accel Axis . . : %i\n", cfg->reverse_accel_axis);
     dprintf("Wheel: ---  End  configuration ---\n");
 
-    swdc_di_off_brake = accel_axis->off;
+    swdc_di_off_brake = brake_axis->off;
-    swdc_di_off_accel = brake_axis->off;
+    swdc_di_off_accel = accel_axis->off;
     swdc_di_start = cfg->start;
     swdc_di_view_chg = cfg->view_chg;
     swdc_di_shift_dn = cfg->shift_dn;

swdcio/xi.c

@@ -1,6 +1,7 @@
 #include <windows.h>
 #include <xinput.h>
 
+#include <math.h>
 #include <assert.h>
 #include <stdbool.h>
 #include <stdint.h>
@@ -23,6 +24,7 @@ static const struct swdc_io_backend swdc_xi_backend = {
 };
 
 static bool swdc_xi_single_stick_steering;
+static bool swdc_xi_linear_steering;
 
 HRESULT swdc_xi_init(const struct swdc_xi_config *cfg, const struct swdc_io_backend **backend)
 {
@@ -51,9 +53,11 @@ static HRESULT swdc_xi_config_apply(const struct swdc_xi_config *cfg)
 {
     dprintf("XInput: --- Begin configuration ---\n");
     dprintf("XInput: Single Stick Steering : %i\n", cfg->single_stick_steering);
+    dprintf("XInput: Linear Steering . . . : %i\n", cfg->linear_steering);
     dprintf("XInput: ---  End  configuration ---\n");
 
     swdc_xi_single_stick_steering = cfg->single_stick_steering;
+    swdc_xi_linear_steering = cfg->linear_steering;
 
     return S_OK;
 }
@@ -123,6 +127,31 @@ static void swdc_xi_get_gamebtns(uint16_t *gamebtn_out)
     *gamebtn_out = gamebtn;
 }
 
+static int apply_non_linear_transform(int value, int deadzone_center) {
+    const int max_input = 32767;
+    const double power_factor = 3.0;
+
+    // Apply deadzone only after passing the center threshold
+    if (abs(value) < deadzone_center) {
+        return 0;
+    }
+
+    // Scale the value to the range [-1.0, 1.0]
+    double scaled_value = (abs(value) - deadzone_center) / (double)(max_input - deadzone_center);
+
+    // Apply a non-linear transform (cubing in this case) and preserve the sign
+    double signed_value = copysign(pow(scaled_value, power_factor), value);
+
+    // Scale the value back to the range [-32770, 32767]
+    int transformed_value = (int)(signed_value * max_input);
+
+    // Clamp the value to the range [-32767, 32767]
+    transformed_value = (transformed_value > max_input) ? max_input : transformed_value;
+    transformed_value = (transformed_value < -max_input) ? -max_input : transformed_value;
+
+    return transformed_value;
+}
+
 static void swdc_xi_get_analogs(struct swdc_io_analog_state *out)
 {
     XINPUT_STATE xi;
@@ -135,23 +164,28 @@ static void swdc_xi_get_analogs(struct swdc_io_analog_state *out)
     XInputGetState(0, &xi);
 
     left = xi.Gamepad.sThumbLX;
-
-    if (left < -XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
-        left += XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
-    } else if (left > XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
-        left -= XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
-    } else {
-        left = 0;
-    }
-
     right = xi.Gamepad.sThumbRX;
 
-    if (right < -XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+    if (!swdc_xi_linear_steering) {
-        right += XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        // Apply non-linear transform for both sticks
-    } else if (right > XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+        left = apply_non_linear_transform(left, XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE);
-        right -= XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        right = apply_non_linear_transform(right, XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE);
     } else {
-        right = 0;
+        if (left < -XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
+            left += XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
+        } else if (left > XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE) {
+            left -= XINPUT_GAMEPAD_LEFT_THUMB_DEADZONE;
+        } else {
+            left = 0;
+        }
+
+        if (right < -XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+            right += XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        } else if (right > XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE) {
+            right -= XINPUT_GAMEPAD_RIGHT_THUMB_DEADZONE;
+        } else {
+            right = 0;
+        }
     }
 
     if (swdc_xi_single_stick_steering) {