From ca67510e704853fbec5874095b6ae1da1764a015 Mon Sep 17 00:00:00 2001
From: Josh Stewart <josh@noisymime.org>
Date: Wed, 4 Feb 2015 11:52:01 +1100
Subject: [PATCH] Minor cleanup of pulsewidth calc.

---
 math.h        | 17 +++++++++++++++--
 speeduino.ino |  2 +-
 utils.h       |  7 ++++---
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/math.h b/math.h
index d0591c2..fe25096 100644
--- a/math.h
+++ b/math.h
@@ -11,8 +11,8 @@ Ref: http://www.hackersdelight.org/divcMore.pdf
 */
 
 //Unsigned divide by 10
-unsigned divu10(unsigned n) {
- unsigned q, r;
+unsigned int divu10(unsigned int n) {
+ unsigned int q, r;
  q = (n >> 1) + (n >> 2);
  q = q + (q >> 4);
  q = q + (q >> 8);
@@ -36,3 +36,16 @@ int divs10(int n) {
  return q + ((r + 6) >> 4);
 // return q + (r > 9);
 }
+
+//Signed divide by 100
+int divs100(int n) {
+ int q, r;
+ n = n + (n>>31 & 99);
+ q = (n >> 1) + (n >> 3) + (n >> 6) - (n >> 10) +
+ (n >> 12) + (n >> 13) - (n >> 16);
+ q = q + (q >> 20);
+ q = q >> 6;
+ r = n - q*100;
+ return q + ((r + 28) >> 7);
+// return q + (r > 99);
+}
diff --git a/speeduino.ino b/speeduino.ino
index 6940cb3..e84eec2 100644
--- a/speeduino.ino
+++ b/speeduino.ino
@@ -359,7 +359,7 @@ void loop()
       //BEGIN INJECTION TIMING
       //Determine next firing angles
       //1
-      int PWdivTimerPerDegree = div(currentStatus.PW, timePerDegree).quot; //This variable is used multiple times, so only do the division once. 
+      int PWdivTimerPerDegree = div(currentStatus.PW, timePerDegree).quot; //How many crank degrees the calculated PW will take at the current speed
       injector1StartAngle = 355 - ( PWdivTimerPerDegree ); //This is a little primitive, but is based on the idea that all fuel needs to be delivered before the inlet valve opens. I am using 355 as the point at which the injector MUST be closed by. See http://www.extraefi.co.uk/sequential_fuel.html for more detail
       //Repeat the above for each cylinder
       //2
diff --git a/utils.h b/utils.h
index fded4e8..dc60ba9 100644
--- a/utils.h
+++ b/utils.h
@@ -50,9 +50,10 @@ unsigned int PW(int REQ_FUEL, byte VE, byte MAP, int corrections, int injOpen, b
     intermediate = (intermediate * iMAP) >> 7;
     intermediate = (intermediate * iCorrections) >> 7;
     intermediate = (intermediate * iTPS) >> 7;
-    unsigned int final = (unsigned int)(intermediate + injOpen);
-    //if (final > 65535) { final = 65535; } //Make sure this won't overflow. This means the maximum pulsewidth possible is 65.535mS
-    return final;
+    intermediate += injOpen; //Add the injector opening time
+    if ( intermediate > 65535) { intermediate = 65535; } //Make sure this won't overflow when we convert to uInt. This means the maximum pulsewidth possible is 65.535mS
+    //unsigned int final = (unsigned int)(intermediate);
+    return (unsigned int)(intermediate);
 
   }