From 56d2fd68c9ddd5abecee09747e6d2e5f246232a4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20Mal=C3=BD?= <madcatxster@gmail.com>
Date: Wed, 18 May 2011 16:31:28 +0200
Subject: [PATCH] Added a formula to calculate DFP wheel range

---
 wheels.c |   46 +++++++++++++++++++++++++++++++++++++---------
 1 files changed, 37 insertions(+), 9 deletions(-)

diff --git a/wheels.c b/wheels.c
index 0b67d65..022bf92 100644
--- a/wheels.c
+++ b/wheels.c
@@ -70,6 +70,27 @@ int get_range_cmd(cmdstruct *c, int range)
 /* used by DFP */
 int get_range_cmd2(cmdstruct *c, int range)
 {
+    //Table of valid values for 6th byte
+    char valid_byte6[] = {
+      0xe0,
+      0xa4,
+      0x86,
+      0x68,
+      0x4a,
+      0x2c,
+      0x0e,
+    };
+    
+    //Which segment to use
+    int segment = (900 - range) / 7;	//Yes, integer division is what we need
+    
+    //Values for 3rd and 4th byte
+    char byte4 = 255 - segment;
+    char byte3 = 255 - byte4;
+    
+    //Set value of 6th byte
+    int byte6_idx = 899 - (segment * 7) - range;
+    
     /* According to MadCatXs investigation this additional
      * cmd is needed to enable rotation range > 200 degrees.
      */
@@ -82,17 +103,24 @@ int get_range_cmd2(cmdstruct *c, int range)
     c->cmds[0][6] = 0x00;
     c->cmds[0][7] = 0x00;
 
-    // FIXME - This is not working, need to find out the correct formula...
-    c->cmds[1][0] = 0xf8;
-    c->cmds[1][1] = 0x81;
-    c->cmds[1][2] = range & 0x00ff;
-    c->cmds[1][3] = (range & 0xff00)>>8;
-    c->cmds[1][4] = 0x00;
-    c->cmds[1][5] = 0x00;
-    c->cmds[1][6] = 0x00;
-    c->cmds[1][7] = 0x00;
+    c->cmds[1][0] = 0x81;
+    c->cmds[1][1] = 0x0b;
+    c->cmds[1][2] = byte3;
+    c->cmds[1][3] = byte4;
+    c->cmds[1][4] = 0xff;
+    c->cmds[1][5] = valid_byte6[byte6_idx];
+    c->cmds[1][6] = 0xff;
+    c->cmds[1][7] = 0x00;	//Logitech driver does not send the 8th byte.
 
     c->numCmds = 2;
+    
+    /*DEBUG
+    int i;
+    printf("%d %d\n", segment, byte6_idx);
+    for(i = 0; i < 7; i++) {
+      printf("%x\n", c->cmds[1][i]);
+    }*/
+    
     return 0;
 }
 
-- 
1.7.5.1