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Fix WMath's map() implementation for inverse/round-trip mapping #7027

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Merged
merged 2 commits into from
Feb 9, 2020
Merged

Fix WMath's map() implementation for inverse/round-trip mapping #7027

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5882902
Fix "improved_map" from Servo.cpp and use this is in core implementat…
dok-net Jan 21, 2020
cd5cbae
Merge branch 'master' into wmath_map
earlephilhower Feb 8, 2020
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10 changes: 5 additions & 5 deletions cores/esp8266/WMath.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -70,11 +70,11 @@ long secureRandom(long howsmall, long howbig) {
}

long map(long x, long in_min, long in_max, long out_min, long out_max) {
long divisor = (in_max - in_min);
if(divisor == 0){
return -1; //AVR returns -1, SAM returns 0
}
return (x - in_min) * (out_max - out_min) / divisor + out_min;
const long dividend = out_max - out_min;
const long divisor = in_max - in_min;
const long delta = x - in_min;

return (delta * dividend + (divisor / 2)) / divisor + out_min;
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This doesn't handle divisor == 0.
}

unsigned int makeWord(unsigned int w) {
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