From 66693914d186d20c4a1c5dc0f0639e825b39f29a Mon Sep 17 00:00:00 2001
From: "Pawel Spychalski (DzikuVx)" <pspychalski@gmail.com>
Date: Thu, 19 Apr 2018 11:18:36 +0200
Subject: [PATCH] improed processing of sbus frames

---
 .vscode/arduino.json          | 2 +-
 .vscode/c_cpp_properties.json | 5 ++++-
 crossbow/crossbow.ino         | 1 -
 crossbow/sbus.cpp             | 8 +++++---
 4 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/.vscode/arduino.json b/.vscode/arduino.json
index 470c2cf..e8e6b14 100644
--- a/.vscode/arduino.json
+++ b/.vscode/arduino.json
@@ -1,6 +1,6 @@
 {
     "board": "bsfrance:avr:lora32u4",
     "sketch": "crossbow/crossbow.ino",
-    "port": "COM3",
+    "port": "COM7",
     "output": "../build"
 }
\ No newline at end of file
diff --git a/.vscode/c_cpp_properties.json b/.vscode/c_cpp_properties.json
index cfa69c7..8e3b549 100644
--- a/.vscode/c_cpp_properties.json
+++ b/.vscode/c_cpp_properties.json
@@ -14,7 +14,10 @@
             "intelliSenseMode": "msvc-x64",
             "cStandard": "c11",
             "cppStandard": "c++17",
-            "compilerPath": "/usr/bin/clang"
+            "compilerPath": "/usr/bin/clang",
+            "defines": [
+                "FEATURE_TX_INPUT_SBUS"
+            ]
         },
         {
             "name": "Mac",
diff --git a/crossbow/crossbow.ino b/crossbow/crossbow.ino
index a880816..3c2f32f 100644
--- a/crossbow/crossbow.ino
+++ b/crossbow/crossbow.ino
@@ -8,7 +8,6 @@ Copyright (c) 20xx, MPL Contributor1 contrib1@example.net
 
 #include "config.h"
 
-
 #include "lora.h"
 #include "variables.h"
 #include "main_variables.h"
diff --git a/crossbow/sbus.cpp b/crossbow/sbus.cpp
index c1fb430..881ccbc 100644
--- a/crossbow/sbus.cpp
+++ b/crossbow/sbus.cpp
@@ -21,12 +21,14 @@ equivalent to
 map(channels[i], RC_CHANNEL_MIN, RC_CHANNEL_MAX, SBUS_MIN_OFFSET, SBUS_MAX_OFFSET);
 */
 int mapChannelToSbus(int in) {
-    return (((long) in * 1605l) / 1000l) - 1417;
+    return ((long) in * 1605l / 1000l) - 1417;
 }
 
+/*
+Precomputed mapping from 173:1811 to 990-2010
+*/
 int mapSbusToChannel(int in) {
-    //TODO, speed up this processing
-    return map(in, 173, 1811, 990, 2010);
+    return (((long) in - 173l) * 1020l / 1638l) + 990;
 }
 
 void sbusPreparePacket(uint8_t packet[], int16_t channels[], bool isSignalLoss, bool isFailsafe){