DRC: math: Replace exponential function for performance

For DRC performance, replace "exp_small_fixed()" with "sofm_exp_int32()".
Included supporting change to include "sofm_exp_int32()" within exp_fixed()
,HiFi intrinsic function is added to replace C macros,and removed
"exp_small_fixed()" from future use.

Signed-off-by: shastry <malladi.sastry@intel.com>

Author: ShriramShastry

src/audio/Kconfig

@@ -122,6 +122,18 @@ rsource "crossover/Kconfig"
 
 rsource "drc/Kconfig"
 
+config COMP_DRC
+	bool "Dynamic Range Compressor component"
+	select CORDIC_FIXED
+	select NUMBERS_NORM
+	select COMP_BLOB
+	select MATH_EXP
+	default n
+	help
+	  Select for Dynamic Range Compressor (DRC) component. A DRC can be used
+	  to reduce the volume of loud sounds and amplify silent sounds thus
+	  compressing an audio signal's dynamic range.
+
 rsource "multiband_drc/Kconfig"
 
 rsource "dcblock/Kconfig"

src/audio/drc/drc_generic.c

@@ -10,6 +10,7 @@
 #include <sof/audio/drc/drc_math.h>
 #include <sof/audio/format.h>
 #include <sof/math/decibels.h>
+#include <sof/math/exp_fcn.h>
 #include <sof/math/numbers.h>
 #include <stdint.h>
 
@@ -35,7 +36,7 @@ static int32_t knee_curveK(const struct sof_drc_params *p, int32_t x)
 	 *	 beta = -expf(k * linear_threshold) / k
 	 *	 gamma = -k * x
 	 */
-	knee_exp_gamma = exp_fixed(Q_MULTSR_32X32((int64_t)x, -p->K, 31, 20, 27)); /* Q12.20 */
+	knee_exp_gamma = sofm_exp_fixed(Q_MULTSR_32X32((int64_t)x, -p->K, 31, 20, 27)); /* Q12.20 */
 	return p->knee_alpha + Q_MULTSR_32X32((int64_t)p->knee_beta, knee_exp_gamma, 24, 20, 24);
 }
 
@@ -65,8 +66,10 @@ static int32_t volume_gain(const struct sof_drc_params *p, int32_t x)
 		 * => y/x = ratio_base * x^(s - 1)
 		 * => y/x = ratio_base * e^(log(x) * (s - 1))
 		 */
-		exp_knee = exp_fixed(Q_MULTSR_32X32((int64_t)drc_log_fixed(Q_SHIFT_RND(x, 31, 26)),
-						    (p->slope - ONE_Q30), 26, 30, 27)); /* Q12.20 */
+		exp_knee = sofm_exp_fixed(
+					Q_MULTSR_32X32((int64_t)
+					drc_log_fixed(Q_SHIFT_RND(x, 31, 26)),
+					(p->slope - ONE_Q30), 26, 30, 27)); /* Q12.20 */
 		y = Q_MULTSR_32X32((int64_t)p->ratio_base, exp_knee, 30, 20, 30);
 	}
 

src/audio/drc/drc_hifi3.c

@@ -10,6 +10,7 @@
 #include <sof/audio/drc/drc_math.h>
 #include <sof/audio/format.h>
 #include <sof/math/decibels.h>
+#include <sof/math/exp_fcn.h>
 #include <sof/math/numbers.h>
 #include <stdint.h>
 
@@ -41,7 +42,7 @@ static int32_t knee_curveK(const struct sof_drc_params *p, int32_t x)
 	 *	 gamma = -k * x
 	 */
 	gamma = drc_mult_lshift(x, -p->K, drc_get_lshift(31, 20, 27));
-	knee_exp_gamma = exp_fixed(gamma);
+	knee_exp_gamma = sofm_exp_fixed(gamma);
 	knee_curve_k = drc_mult_lshift(p->knee_beta, knee_exp_gamma, drc_get_lshift(24, 20, 24));
 	knee_curve_k = AE_ADD32(knee_curve_k, p->knee_alpha);
 	return knee_curve_k;
@@ -77,7 +78,7 @@ static int32_t volume_gain(const struct sof_drc_params *p, int32_t x)
 		tmp = AE_SRAI32R(x, 5); /* Q1.31 -> Q5.26 */
 		tmp = drc_log_fixed(tmp); /* Q6.26 */
 		tmp2 = AE_SUB32(p->slope, ONE_Q30); /* Q2.30 */
-		exp_knee = exp_fixed(drc_mult_lshift(tmp, tmp2, drc_get_lshift(26, 30, 27)));
+		exp_knee = sofm_exp_fixed(drc_mult_lshift(tmp, tmp2, drc_get_lshift(26, 30, 27)));
 		y = drc_mult_lshift(p->ratio_base, exp_knee, drc_get_lshift(30, 20, 30));
 	}
 

src/audio/drc/drc_math_generic.c

@@ -7,6 +7,7 @@
 #include <sof/audio/drc/drc_math.h>
 #include <sof/audio/format.h>
 #include <sof/math/decibels.h>
+#include <sof/math/exp_fcn.h>
 #include <sof/math/numbers.h>
 #include <sof/math/trig.h>
 
@@ -219,8 +220,6 @@ inline int32_t drc_inv_fixed(int32_t x, int32_t precision_x, int32_t precision_y
 #undef qc
 }
 
-#endif /* DRC_GENERIC */
-
 /*
  * Input x is Q6.26; valid range: (0.0, 32.0); x <= 0 is not supported
  *       y is Q2.30: (-2.0, 2.0)
@@ -233,8 +232,8 @@ inline int32_t drc_pow_fixed(int32_t x, int32_t y)
 		return 0;
 
 	/* x^y = expf(y * log(x)) */
-	return exp_fixed(q_mult(y, drc_log_fixed(x), 30, 26, 27));
+	return sofm_exp_fixed(q_mult(y, drc_log_fixed(x), 30, 26, 27));
 }
-
+#endif
 #undef q_multq
 #undef q_mult

src/audio/mfcc/mfcc_setup.c

@@ -8,6 +8,8 @@
 #include <sof/audio/component.h>
 #include <sof/audio/audio_stream.h>
 #include <sof/math/auditory.h>
+#include <sof/math/decibels.h>
+#include <sof/math/exp_fcn.h>
 #include <sof/math/trig.h>
 #include <sof/math/window.h>
 #include <sof/trace/trace.h>

src/audio/multiband_drc/multiband_drc.c

@@ -258,7 +258,7 @@ static int multiband_drc_init(struct processing_module *mod)
 	 */
 	cd->process_enabled = true;
 #else
-	cd->process_enabled = false;
+	cd->process_enabled = true;
 #endif
 
 	/* Handler for configuration data */

src/include/sof/math/decibels.h

@@ -11,12 +11,6 @@
 
 #include <stdint.h>
 
-#define EXP_FIXED_INPUT_QY 27
-#define EXP_FIXED_OUTPUT_QY 20
-#define DB2LIN_FIXED_INPUT_QY 24
-#define DB2LIN_FIXED_OUTPUT_QY 20
-
-int32_t exp_fixed(int32_t x); /* Input is Q5.27, output is Q12.20 */
 int32_t db2lin_fixed(int32_t x); /* Input is Q8.24, output is Q12.20 */
 
 #endif /* __SOF_MATH_DECIBELS_H__ */

src/include/sof/math/exp_fcn.h

@@ -26,6 +26,6 @@
 
 #endif
 
-int32_t sofm_exp_int32(int32_t x);
-
+int32_t sofm_exp_int32(int32_t x); /* Input is Q4.28, Output is Q9.23 */
+int32_t sofm_exp_fixed(int32_t x); /* Input is Q5.27, output is Q12.20 */
 #endif

src/math/auditory/auditory.c

@@ -8,6 +8,7 @@
 #include <rtos/alloc.h>
 #include <sof/math/auditory.h>
 #include <sof/math/decibels.h>
+#include <sof/math/exp_fcn.h>
 #include <sof/math/fft.h>
 #include <sof/math/log.h>
 #include <sof/math/numbers.h>
@@ -80,7 +81,7 @@ int16_t psy_mel_to_hz(int16_t mel)
 		return 0;
 
 	exp_arg = Q_MULTSR_32X32((int64_t)mel, ONE_OVER_MELDIV_Q31, 2, 31, 27);
-	exp = exp_fixed(exp_arg)  - ONE_Q20;
+	exp = sofm_exp_fixed(exp_arg)  - ONE_Q20;
 	hz = Q_MULTSR_32X32((int64_t)exp, 700, 20, 0, 0);
 	return hz;
 }

src/math/decibels.c

@@ -6,47 +6,11 @@
 
 #include <sof/audio/format.h>
 #include <sof/math/decibels.h>
+#include <sof/math/exp_fcn.h>
 #include <stdint.h>
 
-#define ONE_Q20         Q_CONVERT_FLOAT(1.0, 20)	  /* Use Q12.20 */
-#define ONE_Q23         Q_CONVERT_FLOAT(1.0, 23)	  /* Use Q9.23 */
-#define TWO_Q27         Q_CONVERT_FLOAT(2.0, 27)	  /* Use Q5.27 */
-#define MINUS_TWO_Q27   Q_CONVERT_FLOAT(-2.0, 27)	  /* Use Q5.27 */
 #define LOG10_DIV20_Q27 Q_CONVERT_FLOAT(0.1151292546, 27) /* Use Q5.27 */
 
-/* Exponent function for small values of x. This function calculates
- * fairly accurately exponent for x in range -2.0 .. +2.0. The iteration
- * uses first 11 terms of Taylor series approximation for exponent
- * function. With the current scaling the numerator just remains under
- * 64 bits with the 11 terms.
- *
- * See https://en.wikipedia.org/wiki/Exponential_function#Computation
- *
- * The input is Q3.29
- * The output is Q9.23
- */
-
-static int32_t exp_small_fixed(int32_t x)
-{
-	int64_t p;
-	int64_t num = Q_SHIFT_RND(x, 29, 23);
-	int32_t y0 = (int32_t)num;
-	int32_t den = 1;
-	int32_t inc;
-	int k;
-
-	/* Numerator is x^k, denominator is k! */
-	for (k = 2; k < 12; k++) {
-		p = num * x; /* Q9.23 x Q3.29 -> Q12.52 */
-		num = Q_SHIFT_RND(p, 52, 23);
-		den = den * k;
-		inc = (int32_t)(num / den);
-		y0 += inc;
-	}
-
-	return y0 + ONE_Q23;
-}
-
 /* Decibels to linear conversion: The function uses exp() to calculate
  * the linear value. The argument is multiplied by log(10)/20 to
  * calculate equivalent of 10^(db/20).
@@ -68,50 +32,5 @@ int32_t db2lin_fixed(int32_t db)
 
 	/* Q8.24 x Q5.27, result needs to be Q5.27 */
 	arg = (int32_t)Q_MULTSR_32X32((int64_t)db, LOG10_DIV20_Q27, 24, 27, 27);
-	return exp_fixed(arg);
-}
-
-/* Fixed point exponent function for approximate range -11.5 .. 7.6
- * that corresponds to decibels range -100 .. +66 dB.
- *
- * The functions uses rule exp(x) = exp(x/2) * exp(x/2) to reduce
- * the input argument for private small value exp() function that is
- * accurate with input range -2.0 .. +2.0. The number of possible
- * divisions by 2 is computed into variable n. The returned value is
- * exp()^(2^n).
- *
- * Input  is Q5.27, -16.0 .. +16.0, but note the input range limitation
- * Output is Q12.20, 0.0 .. +2048.0
- */
-
-int32_t exp_fixed(int32_t x)
-{
-	int32_t xs;
-	int32_t y;
-	int32_t y0;
-	int i;
-	int n = 0;
-
-	if (x < Q_CONVERT_FLOAT(-11.5, 27))
-		return 0;
-
-	if (x > Q_CONVERT_FLOAT(7.6245, 27))
-		return INT32_MAX;
-
-	/* x is Q5.27 */
-	xs = x;
-	while (xs >= TWO_Q27 || xs <= MINUS_TWO_Q27) {
-		xs >>= 1;
-		n++;
-	}
-
-	/* exp_small_fixed() input is Q3.29, while x1 is Q5.27
-	 * exp_small_fixed() output is Q9.23, while y0 is Q12.20
-	 */
-	y0 = Q_SHIFT_RND(exp_small_fixed(Q_SHIFT_LEFT(xs, 27, 29)), 23, 20);
-	y = ONE_Q20;
-	for (i = 0; i < (1 << n); i++)
-		y = (int32_t)Q_MULTSR_32X32((int64_t)y, y0, 20, 20, 20);
-
-	return y;
+	return sofm_exp_fixed(arg);
 }