ipc4: mixin: Fix HiFi5 impl of 24-bit mixing

AE_ADD24S() expects input arguments to be Q9.23 values. Therefore,
negative 24-bit values in a 32-bit container should have their sign
extended to the upper 8 bits. Our other implementations of 24-bit mixing
all perform sign extension prior to mixing and do not rely on samples
being already sign-extended.

Signed-off-by: Serhiy Katsyuba <serhiy.katsyuba@intel.com>

src/audio/mixin_mixout/mixin_mixout_hifi5.c

@@ -142,7 +142,11 @@ static void mix_s24(struct cir_buf_ptr *sink, int32_t start_sample, int32_t mixe
 			AE_LA32X2X2_IP(in_sample, in_sample1, inu, in);
 			AE_LA32X2X2_IP(out_sample, out_sample1, outu1, out);
 			out--;
-			out_sample = AE_ADD24S(in_sample, out_sample);
+			/* sign extent in samples as AE_ADD24S expects Q9.23 arguments */
+			in_sample  = AE_SLAI24S(AE_MOVF24X2_FROMINT32X2(in_sample), 0);
+			in_sample1 = AE_SLAI24S(AE_MOVF24X2_FROMINT32X2(in_sample1), 0);
+			/* out samples are already sign extended by other mixin in a loop below */
+			out_sample  = AE_ADD24S(in_sample, out_sample);
 			out_sample1 = AE_ADD24S(in_sample1, out_sample1);
 			AE_SA32X2X2_IP(out_sample, out_sample1, outu2, out);
 		}
@@ -152,6 +156,8 @@ static void mix_s24(struct cir_buf_ptr *sink, int32_t start_sample, int32_t mixe
 		for (i = 0; i < left; i++) {
 			AE_L32_IP(in_sample, (ae_int32 *)in, sizeof(ae_int32));
 			AE_L32_IP(out_sample, (ae_int32 *)out, 0);
+			/* sign extension */
+			in_sample = AE_SLAI24S(AE_MOVF24X2_FROMINT32X2(in_sample), 0);
 			out_sample = AE_ADD24S(in_sample, out_sample);
 			AE_S32_L_IP(out_sample, (ae_int32 *)out, sizeof(ae_int32));
 		}
@@ -171,12 +177,17 @@ static void mix_s24(struct cir_buf_ptr *sink, int32_t start_sample, int32_t mixe
 		left = n & 3;
 		for (i = 0; i < m; i++) {
 			AE_LA32X2X2_IP(in_sample, in_sample1, inu, in);
+			/* sign extension */
+			in_sample  = AE_SLAI24S(AE_MOVF24X2_FROMINT32X2(in_sample), 0);
+			in_sample1 = AE_SLAI24S(AE_MOVF24X2_FROMINT32X2(in_sample1), 0);
 			AE_SA32X2X2_IP(in_sample, in_sample1, outu2, out);
 		}
 		AE_SA128POS_FP(outu2, out);
 		/* process the left samples to avoid memory access overrun */
 		for (i = 0; i < left; i++) {
 			AE_L32_IP(in_sample, (ae_int32 *)in, sizeof(ae_int32));
+			/* sign extension */
+			in_sample = AE_SLAI24S(AE_MOVF24X2_FROMINT32X2(in_sample), 0);
 			AE_S32_L_IP(in_sample, (ae_int32 *)out, sizeof(ae_int32));
 		}
 	}