From ff14fd7facbf9b9129202417aa150aa324824473 Mon Sep 17 00:00:00 2001
From: Tau <tau@nowhere>
Date: Mon, 21 Oct 2019 22:12:05 -0400
Subject: [PATCH] idzio: Restrict maximum wheel ADC abs. value

---
 idzio/config.c  |  3 ++-
 idzio/config.h  |  1 +
 idzio/dllmain.c | 18 +++++++++++++++---
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/idzio/config.c b/idzio/config.c
index 2b18edee..2422d1a1 100644
--- a/idzio/config.c
+++ b/idzio/config.c
@@ -57,6 +57,7 @@ void idz_di_config_load(struct idz_di_config *cfg, const wchar_t *filename)
         swprintf_s(key, _countof(key), L"gear%i", i + 1);
         cfg->gear[i] = GetPrivateProfileIntW(L"dinput", key, i + 1, filename);
     }
+
 }
 
 void idz_io_config_load(struct idz_io_config *cfg, const wchar_t *filename)
@@ -67,6 +68,7 @@ void idz_io_config_load(struct idz_io_config *cfg, const wchar_t *filename)
     cfg->vk_test = GetPrivateProfileIntW(L"io3", L"test", '1', filename);
     cfg->vk_service = GetPrivateProfileIntW(L"io3", L"service", '2', filename);
     cfg->vk_coin = GetPrivateProfileIntW(L"io3", L"coin", '3', filename);
+    cfg->restrict_ = GetPrivateProfileIntW(L"io3", L"restrict", 196, filename);
 
     GetPrivateProfileStringW(
             L"io3",
@@ -93,4 +95,3 @@ void idz_shifter_config_load(
             0,
             filename);
 }
-
diff --git a/idzio/config.h b/idzio/config.h
index d91b5f3d..0c2b9f3f 100644
--- a/idzio/config.h
+++ b/idzio/config.h
@@ -25,6 +25,7 @@ struct idz_io_config {
     uint8_t vk_service;
     uint8_t vk_coin;
     wchar_t mode[8];
+    int restrict_;
     struct idz_shifter_config shifter;
     struct idz_di_config di;
 };
diff --git a/idzio/dllmain.c b/idzio/dllmain.c
index 3ced7fe7..ee97ba06 100644
--- a/idzio/dllmain.c
+++ b/idzio/dllmain.c
@@ -73,12 +73,24 @@ void idz_io_jvs_read_shifter(uint8_t *gear)
     idz_io_backend->jvs_read_shifter(gear);
 }
 
-void idz_io_jvs_read_analogs(struct idz_io_analog_state *state)
+void idz_io_jvs_read_analogs(struct idz_io_analog_state *out)
 {
-    assert(state != NULL);
+    struct idz_io_analog_state tmp;
+
+    assert(out != NULL);
     assert(idz_io_backend != NULL);
 
-    idz_io_backend->jvs_read_analogs(state);
+    idz_io_backend->jvs_read_analogs(&tmp);
+
+    /* Apply steering wheel restriction. Real cabs only report about 77% of
+       the IO-3's max ADC output value when the wheel is turned to either of
+       its maximum positions. To match this behavior we set the default value
+       for the wheel restriction config parameter to 196 (out of 256). This
+       scaling factor is applied using fixed-point arithmetic below. */
+
+    out->wheel = (tmp.wheel * idz_io_cfg.restrict_) / 256;
+    out->accel = tmp.accel;
+    out->brake = tmp.brake;
 }
 
 void idz_io_jvs_read_coin_counter(uint16_t *out)