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improved and very fast map()

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added map0() that should be used when the input value range is starting at 0. fast and very accurate, much better than map() or map2().
This commit is contained in:
Frank
2025-11-26 19:41:13 +01:00
committed by GitHub
parent d26c751281
commit 04c466cd6f
1 changed files with 14 additions and 0 deletions
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14
wled00/FX.cpp
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@@ -98,6 +98,7 @@ static float mapf(float x, float in_min, float in_max, float out_min, float out_
// more accurate integer version of map() - based on map3() proposed in https://forum.arduino.cc/t/how-map-loses-precision-and-how-to-fix-it/371026/3
// rounding instead of truncation, better handling of inverted ranges
// Important: don't use when the input range is very small, because the output is such cases is worse than map()
static long map2(long x, long in_min, long in_max, long out_min, long out_max)
{
long out_range = out_max - out_min;
@@ -113,6 +114,19 @@ static long map2(long x, long in_min, long in_max, long out_min, long out_max)
return ((x - in_min) * out_range) / in_range + out_min;
}
// better "map" that can be used when in_min = out_min = 0.
// Fast and accurate (error always below 0.5)
static inline uint32_t map0(uint32_t val, uint32_t in_max, uint32_t out_max) {
if (in_max == 0) return 0; // avoid division by zero
return ( (val*out_max) + (in_max/2) ) / in_max; // +(in_max/2) for rounding
}
// a variant of map0() that handles output ranges not starting at 0 - but still requires val in [0 ... in_max]
static inline int32_t map0(uint32_t val, uint32_t in_max, int32_t out_min, int32_t out_max) {
if (out_min > out_max) std::swap(out_min, out_max); // a hack, just to treat inverted ranges without producing overflows
int range = out_max - out_min;
return int(map0(val, in_max, unsigned(range))) + out_min;
}
static um_data_t* getAudioData() {
um_data_t *um_data;