From 0e1a37e38ee99d00cd5d39612e335735a5f7e5be Mon Sep 17 00:00:00 2001
From: Giulio Moro <giuliomoro@yahoo.it>
Date: Mon, 9 Dec 2024 02:25:09 +0100
Subject: [PATCH] LOG_OUTPUT: logarithmically map outputs to CV (disabled).
 Applies to all outputs.

---
 TrillRack.cpp | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/TrillRack.cpp b/TrillRack.cpp
index 09c1fc2..582e31e 100644
--- a/TrillRack.cpp
+++ b/TrillRack.cpp
@@ -30,6 +30,7 @@ extern ButtonView performanceBtn;
 extern void ledSlidersFixedButtonsProcess(LedSliders& sl, std::vector<bool>& states, std::vector<size_t>& onsets, std::vector<size_t>& offsets, bool onlyUpdateStates);
 std::array<float,kNumOutChannels> gManualAnOut;
 
+// #define LOG_OUTPUT
 #define STM32_NEOPIXEL
 // #define PRINT_CPU_TIME
 // Gliss revs:
@@ -507,6 +508,29 @@ class Smoother
 	}
 };
 
+#ifdef LOG_OUTPUT
+static float doLog(float value)
+{
+	static std::array<float,1000> logTable;
+	static bool inited = false;
+	if(!inited)
+	{
+		inited = true;
+		// let's handle log sliders the way Pd does
+	    float min = 1;
+	    float max = 101;
+	    for(size_t n = 0; n < logTable.size(); ++n) {
+	        logTable[n] = (min * exp(log(max/min) * (n / float(logTable.size() - 1))) - 1) / (max - min);
+	    }
+	}
+	value = constrain(value, 0, 1);
+	size_t prevIdx = std::min(logTable.size() - 1, size_t(value * (logTable.size() - 1)));
+	float prev = logTable[prevIdx];
+	float next = logTable[std::min(prevIdx + 1, logTable.size() - 1)];
+	return linearInterpolation(fmodf(value, 1), prev, next);
+}
+#endif // LOG_OUTPUT
+
 static float rescaleOutput(bool ignoreRange, size_t channel, const CalibrationData& cal, float value)
 {
 	float gnd = cal.values[1];
@@ -518,6 +542,9 @@ static float rescaleOutput(bool ignoreRange, size_t channel, const CalibrationDa
 		getRangeMinMax(false, channel, min, top);
 
 	// the input can be negative: out of the specified range but possibly still within the capabilities of the module
+#ifdef LOG_OUTPUT
+	value = doLog(value);
+#endif // LOG_OUTPUT
 	value = map(value, 0, 1, min, top);
 	value = processRawThroughCalibration(cal, false, value);
 	// we only constrain at the end: can't write outside full scale