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Minor fast_sin optimization

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narno2202 2026-01-18 15:16:47 +01:00 • committed by narno2202
parent b7d8751429
commit 62c76c2c17
1 changed files with 7 additions and 5 deletions
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12
Marlin/src/feature/resonance/resonance_generator.cpp
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@ -80,11 +80,10 @@ void ResonanceGenerator::reset() {
// Fast sine approximation
float ResonanceGenerator::fast_sin(float x) {
static constexpr float INV_TAU = (1.0f / M_TAU);
// Reduce the angle to [-π, π]
const float y = x * INV_TAU; // Multiples of 2π
int k = static_cast<int>(y); // Truncates toward zero
const float y = x * (1.0f / M_TAU); // Multiples of 2π
int k = static_cast<int>(y); // Truncates toward zero
// Negative? The truncation is one too high.
if (y < 0.0f) --k; // Correct for negatives
@ -95,8 +94,11 @@ float ResonanceGenerator::fast_sin(float x) {
else if (r < -M_PI)
r += M_TAU;
// Cheap polynomial approximation of sin(r)
return r * (1.27323954f - 0.405284735f * ABS(r));
// Optimized polynomial approximation
// Using sin(x) ≈ x(1 - (x²/π²) * 0.785398163) where 0.785398163 ≈ 1/π
const float r2 = r * r;
return r * (1.0f - 0.101321184f * r2);
}
void ResonanceGenerator::fill_stepper_plan_buffer() {