Audio: Crossover: Change to HiFi5 optimized DF1 IIR type

The direct-form I (DF1) is compatible with direct-form-transposed
(DF2T). The filter type is changed since DF1 is better potential
for optimization for SIMD.

In a HiFi5 platform this change saves with two band crossover
0.8 MCPS, from 10.02 MCPS to 9.26 MCPS. The saving will be higher
in higher order filter banks such as in multiband DRC component.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>

Author: singalsu

src/audio/crossover/crossover.c

@@ -18,7 +18,7 @@
 #include <rtos/alloc.h>
 #include <rtos/init.h>
 #include <sof/lib/uuid.h>
-#include <sof/math/iir_df2t.h>
+#include <sof/math/iir_df1.h>
 #include <sof/list.h>
 #include <sof/platform.h>
 #include <rtos/string.h>
@@ -157,13 +157,13 @@ static int crossover_assign_sinks(struct processing_module *mod,
  * \param[out] lr4 initialized struct
  */
 static int crossover_init_coef_lr4(struct sof_eq_iir_biquad *coef,
-				   struct iir_state_df2t *lr4)
+				   struct iir_state_df1 *lr4)
 {
 	int ret;
 
 	/* Only one set of coefficients is stored in config for both biquads
 	 * in series due to identity. To maintain the structure of
-	 * iir_state_df2t, it requires two copies of coefficients in a row.
+	 * iir_state_df1, it requires two copies of coefficients in a row.
 	 */
 	lr4->coef = rzalloc(SOF_MEM_ZONE_RUNTIME, 0, SOF_MEM_CAPS_RAM,
 			    sizeof(struct sof_eq_iir_biquad) * 2);

src/audio/crossover/crossover.h

@@ -8,7 +8,7 @@
 #define __SOF_AUDIO_CROSSOVER_CROSSOVER_H__
 
 #include <sof/audio/module_adapter/module/module_interface.h>
-#include <sof/math/iir_df2t.h>
+#include <sof/math/iir_df1.h>
 #include <module/crossover/crossover_common.h>
 #include <sof/platform.h>
 #include <stdint.h>
@@ -119,10 +119,10 @@ extern const size_t crossover_split_fncount;
  * \brief Runs input in through the LR4 filter and returns it's output.
  */
 static inline int32_t crossover_generic_process_lr4(int32_t in,
-						    struct iir_state_df2t *lr4)
+						    struct iir_state_df1 *lr4)
 {
 	/* Cascade two biquads with same coefficients in series. */
-	return iir_df2t(lr4, in);
+	return iir_df1(lr4, in);
 }
 
 static inline void crossover_free_config(struct sof_crossover_config **config)

src/audio/crossover/crossover_generic.c

@@ -8,7 +8,7 @@
 #include <sof/audio/module_adapter/module/module_interface.h>
 #include <sof/audio/component.h>
 #include <sof/audio/format.h>
-#include <sof/math/iir_df2t.h>
+#include <sof/math/iir_df1.h>
 #include <stdint.h>
 
 #include "crossover.h"
@@ -21,8 +21,8 @@
  * As a side effect, this function mutates the delay values of both
  * filters.
  */
-static inline void crossover_generic_lr4_split(struct iir_state_df2t *lp,
-					       struct iir_state_df2t *hp,
+static inline void crossover_generic_lr4_split(struct iir_state_df1 *lp,
+					       struct iir_state_df1 *hp,
 					       int32_t x, int32_t *y1,
 					       int32_t *y2)
 {
@@ -39,8 +39,8 @@ static inline void crossover_generic_lr4_split(struct iir_state_df2t *lp,
  * to be out of phase. We need to pass the signal through another set of LR4
  * filters to align back the phase.
  */
-static inline void crossover_generic_lr4_merge(struct iir_state_df2t *lp,
-					       struct iir_state_df2t *hp,
+static inline void crossover_generic_lr4_merge(struct iir_state_df1 *lp,
+					       struct iir_state_df1 *hp,
 					       int32_t x, int32_t *y)
 {
 	int32_t z1, z2;

src/include/module/crossover/crossover_common.h

@@ -8,7 +8,7 @@
 #ifndef __SOF_CROSSOVER_COMMON_H__
 #define __SOF_CROSSOVER_COMMON_H__
 
-#include <sof/math/iir_df2t.h>
+#include <sof/math/iir_df1.h>
 #include <user/eq.h>
 
 /* Number of sinks for a 2 way crossover filter */
@@ -29,8 +29,8 @@
  */
 struct crossover_state {
 	/* Store the state for each LR4 filter. */
-	struct iir_state_df2t lowpass[CROSSOVER_MAX_LR4];
-	struct iir_state_df2t highpass[CROSSOVER_MAX_LR4];
+	struct iir_state_df1 lowpass[CROSSOVER_MAX_LR4];
+	struct iir_state_df1 highpass[CROSSOVER_MAX_LR4];
 };
 
 typedef void (*crossover_split)(int32_t in, int32_t out[],
@@ -46,7 +46,7 @@ int crossover_init_coef_ch(struct sof_eq_iir_biquad *coef,
 /**
  * \brief Reset the state of an LR4 filter.
  */
-static inline void crossover_reset_state_lr4(struct iir_state_df2t *lr4)
+static inline void crossover_reset_state_lr4(struct iir_state_df1 *lr4)
 {
 	rfree(lr4->coef);
 	rfree(lr4->delay);