vibe code the initial impl

2026-10-13 19:47:46 -05:00
parent 7da1c2119d
commit 7862a09858
39 changed files with 2867 additions and 157 deletions
@@ -0,0 +1,26 @@
+// Host stand-in for esp-dsp: float32 radix-2 FFT with the same call sequence
+// (fft2r then bit_rev). Output order is natural, so bit_rev is a no-op here.
+#pragma once
+#include <math.h>
+#include "esp_err.h"
+static inline esp_err_t dsps_fft2r_init_fc32(float *t, int n) { (void)t; (void)n; return ESP_OK; }
+static inline esp_err_t dsps_fft2r_fc32(float *d, int n)
+{
+    for (int i = 1, j = 0; i < n; i++) {           // bit-reverse permutation
+        int bit = n >> 1;
+        for (; j & bit; bit >>= 1) j ^= bit;
+        j ^= bit;
+        if (i < j) { float a = d[2*i], b = d[2*i+1]; d[2*i] = d[2*j]; d[2*i+1] = d[2*j+1]; d[2*j] = a; d[2*j+1] = b; }
+    }
+    for (int len = 2; len <= n; len <<= 1) {
+        float ang = -2.0f * (float)M_PI / (float)len;
+        for (int i = 0; i < n; i += len) for (int k = 0; k < len / 2; k++) {
+            float wr = cosf(ang * k), wi = sinf(ang * k);
+            int a = i + k, b = i + k + len / 2;
+            float xr = d[2*b] * wr - d[2*b+1] * wi, xi = d[2*b] * wi + d[2*b+1] * wr;
+            d[2*b] = d[2*a] - xr; d[2*b+1] = d[2*a+1] - xi; d[2*a] += xr; d[2*a+1] += xi;
+        }
+    }
+    return ESP_OK;
+}
+static inline esp_err_t dsps_bit_rev_fc32(float *d, int n) { (void)d; (void)n; return ESP_OK; }