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Small calculation tweak to remove unnecessary divisions

This commit is contained in:
Josh Stewart 2015-02-06 21:30:19 +11:00
parent 7b85d8e93c
commit bd2fe2e660
1 changed files with 5 additions and 5 deletions
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10
utils.h
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@ -39,20 +39,20 @@ unsigned int PW(int REQ_FUEL, byte VE, byte MAP, int corrections, int injOpen, b
{
//Standard float version of the calculation
//return (REQ_FUEL * (float)(VE/100.0) * (float)(MAP/100.0) * (float)(TPS/100.0) * (float)(corrections/100.0) + injOpen);
//Note: The MAP and TPS portions are currently disabled, we use VE and corrections only
//100% float free version, does sacrifice a little bit of accuracy.
int iVE = ((int)VE << 7) / 100;
int iMAP = ((int)MAP << 7) / 100;
//int iMAP = ((int)MAP << 7) / 100;
int iCorrections = (corrections << 7) / 100;
int iTPS = ((int)TPS << 7) / 100;
//int iTPS = ((int)TPS << 7) / 100;
unsigned long intermediate = ((long)REQ_FUEL * (long)iVE) >>7; //Need to use an intermediate value to avoid overflowing the long
intermediate = (intermediate * iMAP) >> 7;
//intermediate = (intermediate * iMAP) >> 7;
intermediate = (intermediate * iCorrections) >> 7;
intermediate = (intermediate * iTPS) >> 7;
//intermediate = (intermediate * iTPS) >> 7;
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);
}