feat(audio): tone_gen sinus pur + test host

Composant tone_gen : generation sinus stereo entrelace (L==R),
sans dependance IDF, teste en host TDD (4/4 assertions OK).
Build IDF vert : libtone_gen.a compile en [1321/1335].

components/tone_gen/CMakeLists.txt

@@ -0,0 +1,4 @@
+idf_component_register(
+    SRCS "tone_gen.c"
+    INCLUDE_DIRS "include"
+)

components/tone_gen/include/tone_gen.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Fill `buf` with n_frames stereo frames (L == R) of a sine wave.
+ * buf must hold n_frames*2 int16_t. *phase is the running mono sample index,
+ * advanced by n_frames. amplitude is the peak amplitude in int16 units. */
+void tone_gen_fill_stereo(int16_t *buf, int n_frames, uint32_t *phase,
+                          float freq_hz, float amplitude, uint32_t sample_rate);
+
+#ifdef __cplusplus
+}
+#endif

components/tone_gen/test_tone_gen.c

@@ -0,0 +1,37 @@
+/* Test host pur (compilé avec cc, hors IDF) pour tone_gen_fill_stereo. */
+#include "tone_gen.h"
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+
+int main(void)
+{
+    int16_t buf[8 * 2];
+    uint32_t phase = 0;
+
+    /* 1. À phase 0, sin(0) = 0 → premier échantillon nul, L == R. */
+    tone_gen_fill_stereo(buf, 8, &phase, 440.0f, 8000.0f, 16000);
+    assert(buf[0] == 0);
+    assert(buf[1] == 0);
+    for (int i = 0; i < 8; i++) assert(buf[i*2] == buf[i*2+1]); /* L == R */
+
+    /* 2. La phase a avancé de 8 échantillons. */
+    assert(phase == 8);
+
+    /* 3. Amplitude bornée par l'amplitude crête demandée (+1 d'arrondi). */
+    uint32_t ph2 = 0;
+    int16_t buf2[64 * 2];
+    tone_gen_fill_stereo(buf2, 64, &ph2, 440.0f, 8000.0f, 16000);
+    for (int i = 0; i < 64; i++) {
+        assert(buf2[i*2] <= 8001 && buf2[i*2] >= -8001);
+    }
+
+    /* 4. Valeur conforme au sinus attendu à un index connu (phase=4, 440Hz/16k). */
+    float expected = 8000.0f * sinf(2.0f * (float)M_PI * 440.0f * 4.0f / 16000.0f);
+    /* buf2[4] correspond à phase==4 (rempli depuis phase 0). */
+    int16_t got = buf2[4 * 2];
+    assert(fabsf((float)got - expected) < 2.0f);
+
+    printf("tone_gen: 4/4 assertions OK\n");
+    return 0;
+}

components/tone_gen/tone_gen.c

@@ -0,0 +1,19 @@
+#include "tone_gen.h"
+#include <math.h>
+
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
+void tone_gen_fill_stereo(int16_t *buf, int n_frames, uint32_t *phase,
+                          float freq_hz, float amplitude, uint32_t sample_rate)
+{
+    for (int i = 0; i < n_frames; i++) {
+        float s = amplitude * sinf(2.0f * (float)M_PI * freq_hz *
+                                   (float)(*phase) / (float)sample_rate);
+        int16_t v = (int16_t)s;
+        buf[i * 2]     = v;  /* L */
+        buf[i * 2 + 1] = v;  /* R */
+        (*phase)++;
+    }
+}