P2: level-tracker UPDATE-loop located (inline bidirectional IIR in FUN_180529fe0), structural module leveltrack (iir_first_order/bidirectional/unrolled4); scalar==unrolled verified; remaining = live A[] coeffs

dsp/leveltrack_check.cpp

@@ -0,0 +1,31 @@
+#include <cstdio>
+#include <cmath>
+#include <vector>
+#include <cstring>
+#include "leveltrack.hpp"
+
+int main() {
+    const size_t n = 37;  // odd size to exercise the unrolled tail.
+    std::vector<double> A(n);
+    std::vector<float> x1(n), x2(n);
+    for (size_t i = 0; i < n; i++) {
+        A[i] = 0.05 + 0.9 * double(1 + i % 3) / 3.0;  // nontrivial profile
+        x1[i] = static_cast<float>(0.5 * std::sin(0.3 * i) * (1 + i * 0.01));
+    }
+    std::memcpy(x2.data(), x1.data(), n * sizeof(float));
+
+    leveltrack::iir_first_order(x1.data(), A.data(), n);
+    leveltrack::iir_first_order_unrolled4(x2.data(), A.data(), n);
+
+    double maxd = 0.0;
+    for (size_t i = 0; i < n; i++) maxd = std::fmax(maxd, std::fabs(x1[i] - x2[i]));
+    std::printf("scalar vs unrolled4 max|dx| = %.3e  (%s)\n",
+                maxd, maxd < 1e-6 ? "OK" : "MISMATCH");
+
+    // bidirectional: equals applying forward then reverse.
+    std::vector<float> rx(n);
+    leveltrack::iir_bidirectional(rx.data(), A.data(), n);
+
+    std::printf("leveltrack integration check done (n=%zu)\n", n);
+    return maxd < 1e-6 ? 0 : 1;
+}