finalized bw_comp + fixed missing smooth init + examples

TODO

@@ -75,6 +75,7 @@ code:
 * reset_state_multi allow NULL input?
 * process allow NULL output?
 * #if __cplusplus >= 201103L ? - see https://stackoverflow.com/questions/5047971/how-do-i-check-for-c11-support
+* get current compression level, knee
 
 build system:
 * make makefiles handle paths with spaces etc

examples/fx_comp/src/bw_example_fx_comp.c

@@ -30,7 +30,7 @@ void bw_example_fx_comp_set_sample_rate(bw_example_fx_comp *instance, float samp
 
 void bw_example_fx_comp_reset(bw_example_fx_comp *instance) {
 	bw_comp_reset_coeffs(&instance->comp_coeffs);
-	bw_comp_reset_state(&instance->comp_coeffs, &instance->comp_state);
+	bw_comp_reset_state(&instance->comp_coeffs, &instance->comp_state, 0.f, 0.f);
 }
 
 void bw_example_fx_comp_process(bw_example_fx_comp *instance, const float** x, float** y, int n_samples) {

examples/fx_comp/vst3/Makefile

@@ -4,3 +4,6 @@ NAME := bw_example_fx_comp
 SOURCES = ${SOURCES_COMMON} ${ROOT_DIR}/../src/bw_example_fx_comp.c
 
 include ${ROOT_DIR}/../../common/vst3/vst3.mk
+
+CXXFLAGS += -DRELEASE=1 -DNDEBUG -DBW_NO_DEBUG
+#CXXFLAGS += -DDEVELOPMENT=1 -DBW_DEBUG_DEEP

examples/fxpp_comp/vst3/Makefile

@@ -4,3 +4,6 @@ NAME := bw_example_fxpp_comp
 SOURCES = ${SOURCES_COMMON} ${ROOT_DIR}/../src/bw_example_fxpp_comp.cpp
 
 include ${ROOT_DIR}/../../common/vst3/vst3.mk
+
+CXXFLAGS += -DRELEASE=1 -DNDEBUG -DBW_NO_DEBUG
+#CXXFLAGS += -DDEVELOPMENT=1 -DBW_DEBUG_DEEP

include/bw_comp.h

@@ -45,6 +45,7 @@
  *          <li>Moved C++ code to C header.</li>
  *          <li>Added overloaded C++ <code>process()</code> function taking
  *              C-style arrays as arguments.</li>
+ *          <li>Fixed missing smoothing filter initialization.</li>
  *          <li>Removed usage of reserved identifiers.</li>
  *          <li>Clearly specified parameter validity ranges.</li>
  *          <li>Added debugging code.</li>
@@ -290,6 +291,34 @@ static inline void bw_comp_set_gain_dB(
  *    `value` must be less than or equal to `770.630f`.
  *
  *    Default value: `0.f`.
+ *
+ *    #### bw_comp_coeffs_is_valid()
+ *  ```>>> */
+static inline char bw_comp_coeffs_is_valid(
+	const bw_comp_coeffs * BW_RESTRICT coeffs);
+/*! <<<```
+ *    Tries to determine whether `coeffs` is valid and returns non-`0` if it
+ *    seems to be the case and `0` if it is certainly not. False positives are
+ *    possible, false negatives are not.
+ *
+ *    `coeffs` must at least point to a readable memory block of size greater
+ *    than or equal to that of `bw_comp_coeffs`.
+ *
+ *    #### bw_comp_state_is_valid()
+ *  ```>>> */
+static inline char bw_comp_state_is_valid(
+	const bw_comp_coeffs * BW_RESTRICT coeffs,
+	const bw_comp_state * BW_RESTRICT  state);
+/*! <<<```
+ *    Tries to determine whether `state` is valid and returns non-`0` if it
+ *    seems to be the case and `0` if it is certainly not. False positives are
+ *    possible, false negatives are not.
+ *
+ *    If `coeffs` is not `NULL` extra cross-checks might be performed (`state`
+ *    is supposed to be associated to `coeffs`).
+ *
+ *    `state` must at least point to a readable memory block of size greater
+ *    than or equal to that of `bw_comp_state`.
  *  }}} */
 
 #ifdef __cplusplus
@@ -357,6 +386,7 @@ static inline void bw_comp_init(
 
 	bw_env_follow_init(&coeffs->env_follow_coeffs);
 	bw_gain_init(&coeffs->gain_coeffs);
+	bw_one_pole_init(&coeffs->smooth_coeffs);
 	bw_one_pole_set_tau(&coeffs->smooth_coeffs, 0.05f);
 	coeffs->thresh = 1.f;
 	coeffs->ratio = 1.f;
@@ -414,23 +444,106 @@ static inline float bw_comp_reset_state(
 		bw_comp_state * BW_RESTRICT        state,
 		float                              x_0,
 		float                              x_sc_0) {
-	(void)x_0;
+	BW_ASSERT(coeffs != NULL);
-	bw_env_follow_reset_state(&coeffs->env_follow_coeffs, &state->env_follow_state, x_sc_0);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+	BW_ASSERT(state != NULL);
+	BW_ASSERT(bw_is_finite(x_0));
+
+	const float env = bw_env_follow_reset_state(&coeffs->env_follow_coeffs, &state->env_follow_state, x_sc_0);
+	const float thresh = bw_one_pole_get_y_z1(&coeffs->smooth_thresh_state);
+	float y;
+	if (env > thresh) {
+		float v = thresh * bw_rcpf(env);
+		if (v >= 1.175494350822287e-38f) {
+			v = coeffs->kc * bw_log2f(v);
+			y = v > -126.f ? bw_pow2f(v) * x_0 : thresh;
+		} else
+			y = thresh;
+	} else
+		y = x_0;
+	y = bw_gain_get_gain_cur(&coeffs->gain_coeffs) * y;
+
+#ifdef BW_DEBUG_DEEP
+	state->hash = bw_hash_sdbm("bw_comp_state");
+	state->coeffs_reset_id = coeffs->reset_id;
+#endif
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+	BW_ASSERT_DEEP(bw_comp_state_is_valid(coeffs, state));
+	BW_ASSERT(bw_is_finite(y));
+
+	return y;
 }
 
-static inline void bw_comp_update_coeffs_ctrl(bw_comp_coeffs *BW_RESTRICT coeffs) {
+static inline void bw_comp_reset_state_multi(
+		const bw_comp_coeffs * BW_RESTRICT              coeffs,
+		bw_comp_state * BW_RESTRICT const * BW_RESTRICT state,
+		const float *                                   x_0,
+		const float *                                   x_sc_0,
+		float *                                         y_0,
+		size_t                                          n_channels) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+	BW_ASSERT(state != NULL);
+	BW_ASSERT(x_0 != NULL);
+	BW_ASSERT(x_sc_0 != NULL);
+
+	if (y_0 != NULL)
+		for (size_t i = 0; i < n_channels; i++)
+			y_0[i] = bw_comp_reset_state(coeffs, state[i], x_0[i], x_sc_0[i]);
+	else
+		for (size_t i = 0; i < n_channels; i++)
+			bw_comp_reset_state(coeffs, state[i], x_0[i], x_sc_0[i]);
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+	BW_ASSERT_DEEP(bw_has_only_finite(y_0, n_channels));
+	BW_ASSERT_DEEP(y_0 != NULL ? bw_has_only_finite(y_0, n_channels) : 1);
+}
+
+static inline void bw_comp_update_coeffs_ctrl(
+		bw_comp_coeffs * BW_RESTRICT coeffs) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+
 	bw_env_follow_update_coeffs_ctrl(&coeffs->env_follow_coeffs);
 	bw_gain_update_coeffs_ctrl(&coeffs->gain_coeffs);
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
 }
 
-static inline void bw_comp_update_coeffs_audio(bw_comp_coeffs *BW_RESTRICT coeffs) {
+static inline void bw_comp_update_coeffs_audio(
+		bw_comp_coeffs * BW_RESTRICT coeffs) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+
 	bw_env_follow_update_coeffs_audio(&coeffs->env_follow_coeffs);
 	bw_gain_update_coeffs_audio(&coeffs->gain_coeffs);
 	bw_one_pole_process1(&coeffs->smooth_coeffs, &coeffs->smooth_thresh_state, coeffs->thresh);
 	coeffs->kc = 1.f - bw_one_pole_process1(&coeffs->smooth_coeffs, &coeffs->smooth_ratio_state, coeffs->ratio);
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
 }
 
-static inline float bw_comp_process1(const bw_comp_coeffs *BW_RESTRICT coeffs, bw_comp_state *BW_RESTRICT state, float x, float x_sc) {
+static inline float bw_comp_process1(
+		const bw_comp_coeffs * BW_RESTRICT coeffs,
+		bw_comp_state * BW_RESTRICT        state,
+		float                              x,
+		float                              x_sc) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+	BW_ASSERT(state != NULL);
+	BW_ASSERT_DEEP(bw_comp_state_is_valid(coeffs, state));
+	BW_ASSERT(bw_is_finite(x));
+	BW_ASSERT(bw_is_finite(x_sc));
+
 	const float env = bw_env_follow_process1(&coeffs->env_follow_coeffs, &state->env_follow_state, x_sc);
 	const float thresh = bw_one_pole_get_y_z1(&coeffs->smooth_thresh_state);
 	float y;
@@ -444,52 +557,225 @@ static inline float bw_comp_process1(const bw_comp_coeffs *BW_RESTRICT coeffs, b
 	} else
 		y = x;
 	y = bw_gain_process1(&coeffs->gain_coeffs, y);
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+	BW_ASSERT_DEEP(bw_comp_state_is_valid(coeffs, state));
+	BW_ASSERT(bw_is_finite(y));
+
 	return y;
 }
 
-static inline void bw_comp_process(bw_comp_coeffs *BW_RESTRICT coeffs, bw_comp_state *BW_RESTRICT state, const float *x, const float *x_sc, float *y, size_t n_samples) {
+static inline void bw_comp_process(
+		bw_comp_coeffs * BW_RESTRICT coeffs,
+		bw_comp_state * BW_RESTRICT  state,
+		const float *                x,
+		const float *                x_sc,
+		float *                      y,
+		size_t                       n_samples) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+	BW_ASSERT(state != NULL);
+	BW_ASSERT_DEEP(bw_comp_state_is_valid(coeffs, state));
+	BW_ASSERT(x != NULL);
+	BW_ASSERT_DEEP(bw_has_only_finite(x, n_samples));
+	BW_ASSERT(y != NULL);
+
 	bw_comp_update_coeffs_ctrl(coeffs);
 	for (size_t i = 0; i < n_samples; i++) {
 		bw_comp_update_coeffs_audio(coeffs);
 		y[i] = bw_comp_process1(coeffs, state, x[i], x_sc[i]);
 	}
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+	BW_ASSERT_DEEP(bw_comp_state_is_valid(coeffs, state));
+	BW_ASSERT_DEEP(bw_has_only_finite(y, n_samples));
 }
 
-static inline void bw_comp_process_multi(bw_comp_coeffs *BW_RESTRICT coeffs, bw_comp_state *BW_RESTRICT const *BW_RESTRICT state, const float * const *x, const float * const *x_sc, float * const *y, size_t n_channels, size_t n_samples) {
+static inline void bw_comp_process_multi(
+		bw_comp_coeffs * BW_RESTRICT                    coeffs,
+		bw_comp_state * BW_RESTRICT const * BW_RESTRICT state,
+		const float * const *                           x,
+		const float * const *                           x_sc,
+		float * const *                                 y,
+		size_t                                          n_channels,
+		size_t                                          n_samples) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
+	BW_ASSERT(state != NULL);
+	BW_ASSERT(x != NULL);
+	BW_ASSERT(x_sc != NULL);
+	BW_ASSERT(y != NULL);
+
 	bw_comp_update_coeffs_ctrl(coeffs);
 	for (size_t i = 0; i < n_samples; i++) {
 		bw_comp_update_coeffs_audio(coeffs);
 		for (size_t j = 0; j < n_channels; j++)
 			y[j][i] = bw_comp_process1(coeffs, state[j], x[j][i], x_sc[j][i]);
 	}
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_reset_coeffs);
 }
 
-static inline void bw_comp_set_thresh_lin(bw_comp_coeffs *BW_RESTRICT coeffs, float value) {
+static inline void bw_comp_set_thresh_lin(
+		bw_comp_coeffs * BW_RESTRICT coeffs,
+		float                        value) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
+	BW_ASSERT(bw_is_finite(value));
+	BW_ASSERT(value >= 1e-20f && value <= 1e20f);
+
 	coeffs->thresh = value;
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
 }
 
-static inline void bw_comp_set_thresh_dBFS(bw_comp_coeffs *BW_RESTRICT coeffs, float value) {
+static inline void bw_comp_set_thresh_dBFS(
+		bw_comp_coeffs * BW_RESTRICT coeffs,
+		float                        value) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
+	BW_ASSERT(bw_is_finite(value));
+	BW_ASSERT(value >= -400.f && value <= 400.f);
+
 	coeffs->thresh = bw_dB2linf(value);
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
 }
 
-static inline void bw_comp_set_ratio(bw_comp_coeffs *BW_RESTRICT coeffs, float value) {
+static inline void bw_comp_set_ratio(
+		bw_comp_coeffs * BW_RESTRICT coeffs,
+		float                        value) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
+	BW_ASSERT(bw_is_finite(value));
+	BW_ASSERT(value >= 0.f && value <= 1.f);
+
 	coeffs->ratio = value;
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
 }
 
-static inline void bw_comp_set_attack_tau(bw_comp_coeffs *BW_RESTRICT coeffs, float value) {
+static inline void bw_comp_set_attack_tau(
+		bw_comp_coeffs * BW_RESTRICT coeffs,
+		float                        value) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
+	BW_ASSERT(bw_is_finite(value));
+	BW_ASSERT(value >= 0.f);
+
 	bw_env_follow_set_attack_tau(&coeffs->env_follow_coeffs, value);
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
 }
 
-static inline void bw_comp_set_release_tau(bw_comp_coeffs *BW_RESTRICT coeffs, float value) {
+static inline void bw_comp_set_release_tau(
+		bw_comp_coeffs * BW_RESTRICT coeffs,
+		float                        value) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
+	BW_ASSERT(bw_is_finite(value));
+	BW_ASSERT(value >= 0.f);
+
 	bw_env_follow_set_release_tau(&coeffs->env_follow_coeffs, value);
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
 }
 
-static inline void bw_comp_set_gain_lin(bw_comp_coeffs *BW_RESTRICT coeffs, float value) {
+static inline void bw_comp_set_gain_lin(
+		bw_comp_coeffs * BW_RESTRICT coeffs,
+		float                        value) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
+	BW_ASSERT(bw_is_finite(value));
+
 	bw_gain_set_gain_lin(&coeffs->gain_coeffs, value);
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
 }
 
-static inline void bw_comp_set_gain_dB(bw_comp_coeffs *BW_RESTRICT coeffs, float value) {
+static inline void bw_comp_set_gain_dB(
+		bw_comp_coeffs * BW_RESTRICT coeffs,
+		float                        value) {
+	BW_ASSERT(coeffs != NULL);
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
+	BW_ASSERT(!bw_is_nan(value));
+	BW_ASSERT(value <= 770.630f);
+
 	bw_gain_set_gain_dB(&coeffs->gain_coeffs, value);
+
+	BW_ASSERT_DEEP(bw_comp_coeffs_is_valid(coeffs));
+	BW_ASSERT_DEEP(coeffs->state >= bw_comp_coeffs_state_init);
+}
+
+static inline char bw_comp_coeffs_is_valid(
+		const bw_comp_coeffs * BW_RESTRICT coeffs) {
+	BW_ASSERT(coeffs != NULL);
+
+#ifdef BW_DEBUG_DEEP
+	if (coeffs->hash != bw_hash_sdbm("bw_comp_coeffs"))
+		return 0;
+	if (coeffs->state < bw_comp_coeffs_state_init || coeffs->state > bw_comp_coeffs_state_reset_coeffs)
+		return 0;
+#endif
+
+	if (!bw_is_finite(coeffs->thresh) || coeffs->thresh < 1e-20f || coeffs->thresh > 1e20f)
+		return 0;
+	if (!bw_is_finite(coeffs->ratio) || coeffs->ratio < 0.f || coeffs->ratio > 1.f)
+		return 0;
+
+	if (!bw_one_pole_coeffs_is_valid(&coeffs->smooth_coeffs))
+		return 0;
+
+#ifdef BW_DEBUG_DEEP
+	if (coeffs->state >= bw_comp_coeffs_state_reset_coeffs) {
+		if (!bw_is_finite(coeffs->kc) || coeffs->kc < 0.f || coeffs->kc > 1.f)
+			return 0;
+
+		if (!bw_one_pole_state_is_valid(&coeffs->smooth_coeffs, &coeffs->smooth_thresh_state))
+			return 0;
+		if (!bw_one_pole_state_is_valid(&coeffs->smooth_coeffs, &coeffs->smooth_ratio_state))
+			return 0;
+	}
+#endif
+
+	return bw_env_follow_coeffs_is_valid(&coeffs->env_follow_coeffs)
+		&& bw_gain_coeffs_is_valid(&coeffs->gain_coeffs);
+}
+
+static inline char bw_comp_state_is_valid(
+		const bw_comp_coeffs * BW_RESTRICT coeffs,
+		const bw_comp_state * BW_RESTRICT  state) {
+	BW_ASSERT(state != NULL);
+
+#ifdef BW_DEBUG_DEEP
+	if (state->hash != bw_hash_sdbm("bw_comp_state"))
+		return 0;
+
+	if (coeffs != NULL && coeffs->reset_id != state->coeffs_reset_id)
+		return 0;
+#endif
+
+	(void)coeffs;
+
+	return bw_env_follow_state_is_valid(&coeffs->env_follow_coeffs, &state->env_follow_state);
 }
 
 #ifdef __cplusplus
@@ -509,34 +795,61 @@ class Comp {
 public:
 	Comp();
 
-	void setSampleRate(float sampleRate);
+	void setSampleRate(
+		float sampleRate);
+
 	void reset(
-		float x_0 = 0.f,
+		float               x0 = 0.f,
-		float x_sc_0 = 0.f);
+		float               xSc0 = 0.f,
+		float * BW_RESTRICT y0 = nullptr);
+
 	void reset(
-		const float *x_0,
+		float                                       x0,
-		const float *x_sc_0);
+		float                                       xSc0,
+		std::array<float, N_CHANNELS> * BW_RESTRICT y0);
+
 	void reset(
-		const std::array<float, N_CHANNELS> x_0,
+		const float * x0,
-		const std::array<float, N_CHANNELS> x_sc_0);
+		const float * xSc0,
+		float *       y0 = nullptr);
+
+	void reset(
+		std::array<float, N_CHANNELS>               x0,
+		std::array<float, N_CHANNELS>               xSc0,
+		std::array<float, N_CHANNELS> * BW_RESTRICT y0 = nullptr);
+
 	void process(
 		const float * const * x,
-		const float * const *x_sc,
+		const float * const * xSc,
 		float * const *       y,
 		size_t                nSamples);
+
 	void process(
-		const std::array<const float *, N_CHANNELS> x,
+		std::array<const float *, N_CHANNELS> x,
-		const std::array<const float *, N_CHANNELS> x_sc,
+		std::array<const float *, N_CHANNELS> xSc,
-		const std::array<float *, N_CHANNELS> y,
+		std::array<float *, N_CHANNELS>       y,
 		size_t                                nSamples);
 
-	void setTreshLin(float value);
+	void setTreshLin(
-	void setTreshDBFS(float value);
+		float value);
-	void setRatio(float value);
+
-	void setAttackTau(float value);
+	void setTreshDBFS(
-	void setReleaseTau(float value);
+		float value);
-	void setGainLin(float value);
+
-	void setGainDB(float value);
+	void setRatio(
+		float value);
+
+	void setAttackTau(
+		float value);
+
+	void setReleaseTau(
+		float value);
+
+	void setGainLin(
+		float value);
+
+	void setGainDB(
+		float value);
 /*! <<<...
  *  }
  *  ```
@@ -561,85 +874,107 @@ inline Comp<N_CHANNELS>::Comp() {
 }
 
 template<size_t N_CHANNELS>
-inline void Comp<N_CHANNELS>::setSampleRate(float sampleRate) {
+inline void Comp<N_CHANNELS>::setSampleRate(
+		float sampleRate) {
 	bw_comp_set_sample_rate(&coeffs, sampleRate);
 }
 
 template<size_t N_CHANNELS>
 inline void Comp<N_CHANNELS>::reset(
-		float x_0,
+		float               x0,
-		float x_sc_0) {
+		float               xSc0,
+		float * BW_RESTRICT y0) {
 	bw_comp_reset_coeffs(&coeffs);
+	if (y0 != nullptr)
 		for (size_t i = 0; i < N_CHANNELS; i++)
-		bw_comp_reset_state(&coeffs, states + i, x_0, x_sc_0);
+			y0[i] = bw_comp_reset_state(&coeffs, states + i, x0, xSc0);
+	else
+		for (size_t i = 0; i < N_CHANNELS; i++)
+			bw_comp_reset_state(&coeffs, states + i, x0, xSc0);
 }
 
 template<size_t N_CHANNELS>
 inline void Comp<N_CHANNELS>::reset(
-		const float *x_0,
+		float                                       x0,
-		const float *x_sc_0) {
+		float                                       xSc0,
-	bw_comp_reset_coeffs(&coeffs);
+		std::array<float, N_CHANNELS> * BW_RESTRICT y0) {
-	for (size_t i = 0; i < N_CHANNELS; i++)
+	reset(x0, xSc0, y0 != nullptr ? y0->data() : nullptr);
-		bw_comp_reset_state(&coeffs, states + i, x_0[i], x_sc_0[i]);
 }
 
 template<size_t N_CHANNELS>
 inline void Comp<N_CHANNELS>::reset(
-		const std::array<float, N_CHANNELS> x_0,
+		const float * x0,
-		const std::array<float, N_CHANNELS> x_sc_0) {
+		const float * xSc0,
-	reset(x_0.data(), x_sc_0.data());
+		float *       y0) {
+	bw_comp_reset_coeffs(&coeffs);
+	bw_comp_reset_state_multi(&coeffs, statesP, x0, xSc0, y0, N_CHANNELS);
+}
+
+template<size_t N_CHANNELS>
+inline void Comp<N_CHANNELS>::reset(
+		std::array<float, N_CHANNELS>               x0,
+		std::array<float, N_CHANNELS>               xSc0,
+		std::array<float, N_CHANNELS> * BW_RESTRICT y0) {
+	reset(x0.data(), xSc0.data(), y0 != nullptr ? y0->data() : nullptr);
 }
 
 template<size_t N_CHANNELS>
 inline void Comp<N_CHANNELS>::process(
 		const float * const * x,
-		const float * const *x_sc,
+		const float * const * xSc,
 		float * const *       y,
 		size_t                nSamples) {
-	bw_comp_process_multi(&coeffs, statesP, x, x_sc, y, N_CHANNELS, nSamples);
+	bw_comp_process_multi(&coeffs, statesP, x, xSc, y, N_CHANNELS, nSamples);
 }
 
 template<size_t N_CHANNELS>
 inline void Comp<N_CHANNELS>::process(
-		const std::array<const float *, N_CHANNELS> x,
+		std::array<const float *, N_CHANNELS> x,
-		const std::array<const float *, N_CHANNELS> x_sc,
+		std::array<const float *, N_CHANNELS> xSc,
-		const std::array<float *, N_CHANNELS> y,
+		std::array<float *, N_CHANNELS>       y,
 		size_t                                nSamples) {
-	process(x.data(), x_sc.data(), y.data(), nSamples);
+	process(x.data(), xSc.data(), y.data(), nSamples);
 }
 
 template<size_t N_CHANNELS>
-inline void Comp<N_CHANNELS>::setTreshLin(float value) {
+inline void Comp<N_CHANNELS>::setTreshLin(
+		float value) {
 	bw_comp_set_thresh_lin(&coeffs, value);
 }
 
 template<size_t N_CHANNELS>
-inline void Comp<N_CHANNELS>::setTreshDBFS(float value) {
+inline void Comp<N_CHANNELS>::setTreshDBFS(
+		float value) {
 	bw_comp_set_thresh_dBFS(&coeffs, value);
 }
 
 template<size_t N_CHANNELS>
-inline void Comp<N_CHANNELS>::setRatio(float value) {
+inline void Comp<N_CHANNELS>::setRatio(
+		float value) {
 	bw_comp_set_ratio(&coeffs, value);
 }
 
 template<size_t N_CHANNELS>
-inline void Comp<N_CHANNELS>::setAttackTau(float value) {
+inline void Comp<N_CHANNELS>::setAttackTau(
+		float value) {
 	bw_comp_set_attack_tau(&coeffs, value);
 }
 
 template<size_t N_CHANNELS>
-inline void Comp<N_CHANNELS>::setReleaseTau(float value) {
+inline void Comp<N_CHANNELS>::setReleaseTau(
+		float value) {
 	bw_comp_set_release_tau(&coeffs, value);
 }
 
 template<size_t N_CHANNELS>
-inline void Comp<N_CHANNELS>::setGainLin(float value) {
+inline void Comp<N_CHANNELS>::setGainLin(
+		float value) {
 	bw_comp_set_gain_lin(&coeffs, value);
 }
 
 template<size_t N_CHANNELS>
-inline void Comp<N_CHANNELS>::setGainDB(float value) {
+inline void Comp<N_CHANNELS>::setGainDB(
+		float value) {
 	bw_comp_set_gain_dB(&coeffs, value);
 }