From bef6e9b4aa64b655e64adc752cd6cb7d870068dc Mon Sep 17 00:00:00 2001
From: Tau <tau@nowhere>
Date: Sun, 29 Sep 2019 16:37:02 -0400
Subject: [PATCH] idzio/di-dev.c: Factor out DirectInput device handling

---
 idzio/di-dev.c    | 163 ++++++++++++++++++++++++++++++++++++++++++++++
 idzio/di-dev.h    |  19 ++++++
 idzio/meson.build |   2 +
 3 files changed, 184 insertions(+)
 create mode 100644 idzio/di-dev.c
 create mode 100644 idzio/di-dev.h

diff --git a/idzio/di-dev.c b/idzio/di-dev.c
new file mode 100644
index 0000000..6f66bf0
--- /dev/null
+++ b/idzio/di-dev.c
@@ -0,0 +1,163 @@
+#include <windows.h>
+#include <dinput.h>
+
+#include <assert.h>
+
+#include "idzio/di-dev.h"
+
+#include "util/dprintf.h"
+
+HRESULT idz_di_dev_start(IDirectInputDevice8W *dev, HWND wnd)
+{
+    HRESULT hr;
+
+    assert(dev != NULL);
+    assert(wnd != NULL);
+
+    hr = IDirectInputDevice8_SetCooperativeLevel(
+            dev,
+            wnd,
+            DISCL_BACKGROUND | DISCL_EXCLUSIVE);
+
+    if (FAILED(hr)) {
+        dprintf("DirectInput: SetCooperativeLevel failed: %08x\n", (int) hr);
+
+        return hr;
+    }
+
+    hr = IDirectInputDevice8_SetDataFormat(dev, &c_dfDIJoystick);
+
+    if (FAILED(hr)) {
+        dprintf("DirectInput: SetDataFormat failed: %08x\n", (int) hr);
+
+        return hr;
+    }
+
+    hr = IDirectInputDevice8_Acquire(dev);
+
+    if (FAILED(hr)) {
+        dprintf("DirectInput: Acquire failed: %08x\n", (int) hr);
+
+        return hr;
+    }
+
+    return hr;
+}
+
+void idz_di_dev_start_fx(IDirectInputDevice8W *dev, IDirectInputEffect **out)
+{
+    /* 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
+       feedback protocol works.
+
+       I'm currently developing with an Xbox One Thrustmaster TMX wheel, if
+       we don't perform at least some perfunctory FFB initialization of this
+       nature (or indeed if no DirectInput application is running) then the
+       wheel exhibits considerable resistance, similar to that of a stationary
+       car. Changing cf.lMagnitude to a nonzero value does cause the wheel to
+       continuously turn in the given direction with the given force as one
+       would expect (max magnitude per DirectInput docs is +/- 10000).
+
+       Failure here is non-fatal, we log any errors and move on.
+
+       https://docs.microsoft.com/en-us/previous-versions/windows/desktop/ee416353(v=vs.85)
+    */
+
+    IDirectInputEffect *obj;
+    DWORD axis;
+    LONG direction;
+    DIEFFECT fx;
+    DICONSTANTFORCE cf;
+    HRESULT hr;
+
+    assert(dev != NULL);
+    assert(out != NULL);
+
+    *out = NULL;
+
+    dprintf("DirectInput: Starting force feedback (may take a sec)\n");
+
+    axis = DIJOFS_X;
+    direction = 0;
+
+    memset(&cf, 0, sizeof(cf));
+    cf.lMagnitude = 0;
+
+    memset(&fx, 0, sizeof(fx));
+    fx.dwSize = sizeof(fx);
+    fx.dwFlags = DIEFF_CARTESIAN | DIEFF_OBJECTOFFSETS;
+    fx.dwDuration = INFINITE;
+    fx.dwGain = DI_FFNOMINALMAX;
+    fx.dwTriggerButton = DIEB_NOTRIGGER;
+    fx.dwTriggerRepeatInterval = INFINITE;
+    fx.cAxes = 1;
+    fx.rgdwAxes = &axis;
+    fx.rglDirection = &direction;
+    fx.cbTypeSpecificParams = sizeof(cf);
+    fx.lpvTypeSpecificParams = &cf;
+
+    hr = IDirectInputDevice8_CreateEffect(
+            dev,
+            &GUID_ConstantForce,
+            &fx,
+            &obj,
+            NULL);
+
+    if (FAILED(hr)) {
+        dprintf("DirectInput: DirectInput force feedback unavailable: %08x\n",
+                (int) hr);
+
+        return;
+    }
+
+    hr = IDirectInputEffect_Start(obj, INFINITE, 0);
+
+    if (FAILED(hr)) {
+        IDirectInputEffect_Release(obj);
+        dprintf("DirectInput: DirectInput force feedback start failed: %08x\n",
+                (int) hr);
+
+        return;
+    }
+
+    *out = obj;
+
+    dprintf("DirectInput: Force feedback initialized and set to zero\n");
+}
+
+HRESULT idz_di_dev_poll(
+        IDirectInputDevice8W *dev,
+        HWND wnd,
+        union idz_di_state *out)
+{
+    HRESULT hr;
+    MSG msg;
+
+    assert(dev != NULL);
+    assert(wnd != NULL);
+    assert(out != NULL);
+
+    memset(out, 0, sizeof(*out));
+
+    /* Pump our dummy window's message queue just in case DirectInput or an
+       IHV DirectInput driver somehow relies on it */
+
+    while (PeekMessageW(&msg, wnd, 0, 0, PM_REMOVE)) {
+        TranslateMessage(&msg);
+        DispatchMessage(&msg);
+    }
+
+    hr = IDirectInputDevice8_GetDeviceState(
+            dev,
+            sizeof(out->st),
+            &out->st);
+
+    if (FAILED(hr)) {
+        dprintf("DirectInput: GetDeviceState error: %08x\n", (int) hr);
+    }
+
+    /* JVS lacks a protocol for reporting hardware errors from poll command
+       responses, so this ends up returning zeroed input state instead. */
+
+    return hr;
+}
diff --git a/idzio/di-dev.h b/idzio/di-dev.h
new file mode 100644
index 0000000..9c8b2d2
--- /dev/null
+++ b/idzio/di-dev.h
@@ -0,0 +1,19 @@
+#pragma once
+
+#include <windows.h>
+#include <dinput.h>
+
+#include <stdint.h>
+
+union idz_di_state {
+    DIJOYSTATE st;
+    uint8_t bytes[sizeof(DIJOYSTATE)];
+};
+
+HRESULT idz_di_dev_start(IDirectInputDevice8W *dev, HWND wnd);
+void idz_di_dev_start_fx(IDirectInputDevice8W *dev, IDirectInputEffect **out);
+HRESULT idz_di_dev_poll(
+        IDirectInputDevice8W *dev,
+        HWND wnd,
+        union idz_di_state *out);
+
diff --git a/idzio/meson.build b/idzio/meson.build
index 15fdc4b..ce1668c 100644
--- a/idzio/meson.build
+++ b/idzio/meson.build
@@ -19,6 +19,8 @@ idzio_dll = shared_library(
         'config.h',
         'di.c',
         'di.h',
+        'di-dev.c',
+        'di-dev.h',
         'dllmain.c',
         'idzio.h',
         'shifter.c',