audio: eq_fir: clarify FIR processing variable names

Replace abbreviated local variable names with descriptive names
across the generic, HiFi2EP, and HiFi3 EQ FIR implementations.
Clarify channel, sample, pointer, filter, and stride handling
without changing processing behavior.

Signed-off-by: Piotr Hoppe <piotr.hoppe@intel.com>

Author: piotrhoppeintel

src/audio/eq_fir/eq_fir_generic.c

@@ -26,33 +26,37 @@ void eq_fir_s16(struct fir_state_32x16 fir[], struct cir_buf_source *source,
 		struct cir_buf_sink *sink, int frames, int channels)
 {
 	struct fir_state_32x16 *filter;
-	int32_t z;
-	const int16_t *x0;
-	int16_t *y0;
-	const int16_t *x = source->ptr;
-	int16_t *y = sink->ptr;
-	int nmax, n, i, j;
+	int32_t filtered_sample;
+	const int16_t *src_channel;
+	int16_t *dst_channel;
+	const int16_t *src = source->ptr;
+	int16_t *dst = sink->ptr;
+	int max_samples;
+	int chunk_samples;
+	int sample_index;
+	int channel;
 	int remaining_samples = frames * channels;
 
 	while (remaining_samples) {
-		nmax = cir_buf_samples_without_wrap_s16(x, source->buf_end);
-		n = MIN(remaining_samples, nmax);
-		nmax = cir_buf_samples_without_wrap_s16(y, sink->buf_end);
-		n = MIN(n, nmax);
-		for (j = 0; j < channels; j++) {
-			x0 = x + j;
-			y0 = y + j;
-			filter = &fir[j];
-			for (i = 0; i < n; i += channels) {
-				z = fir_32x16(filter, *x0 << 16);
-				*y0 = sat_int16(Q_SHIFT_RND(z, 31, 15));
-				x0 += channels;
-				y0 += channels;
+		max_samples = cir_buf_samples_without_wrap_s16(src, source->buf_end);
+		chunk_samples = MIN(remaining_samples, max_samples);
+		max_samples = cir_buf_samples_without_wrap_s16(dst, sink->buf_end);
+		chunk_samples = MIN(chunk_samples, max_samples);
+		for (channel = 0; channel < channels; channel++) {
+			src_channel = src + channel;
+			dst_channel = dst + channel;
+			filter = &fir[channel];
+			for (sample_index = 0; sample_index < chunk_samples;
+				sample_index += channels) {
+				filtered_sample = fir_32x16(filter, *src_channel << 16);
+				*dst_channel = sat_int16(Q_SHIFT_RND(filtered_sample, 31, 15));
+				src_channel += channels;
+				dst_channel += channels;
 			}
 		}
-		remaining_samples -= n;
-		x = source_cir_buf_wrap(x + n, source->buf_start, source->buf_end);
-		y = cir_buf_wrap(y + n, sink->buf_start, sink->buf_end);
+		remaining_samples -= chunk_samples;
+		src = source_cir_buf_wrap(src + chunk_samples, source->buf_start, source->buf_end);
+		dst = cir_buf_wrap(dst + chunk_samples, sink->buf_start, sink->buf_end);
 	}
 }
 #endif /* CONFIG_FORMAT_S16LE */
@@ -62,33 +66,37 @@ void eq_fir_s24(struct fir_state_32x16 fir[], struct cir_buf_source *source,
 		struct cir_buf_sink *sink, int frames, int channels)
 {
 	struct fir_state_32x16 *filter;
-	int32_t z;
-	const int32_t *x0;
-	int32_t *y0;
-	const int32_t *x = source->ptr;
-	int32_t *y = sink->ptr;
-	int nmax, n, i, j;
+	int32_t filtered_sample;
+	const int32_t *src_channel;
+	int32_t *dst_channel;
+	const int32_t *src = source->ptr;
+	int32_t *dst = sink->ptr;
+	int max_samples;
+	int chunk_samples;
+	int sample_index;
+	int channel;
 	int remaining_samples = frames * channels;
 
 	while (remaining_samples) {
-		nmax = cir_buf_samples_without_wrap_s32(x, source->buf_end);
-		n = MIN(remaining_samples, nmax);
-		nmax = cir_buf_samples_without_wrap_s32(y, sink->buf_end);
-		n = MIN(n, nmax);
-		for (j = 0; j < channels; j++) {
-			x0 = x + j;
-			y0 = y + j;
-			filter = &fir[j];
-			for (i = 0; i < n; i += channels) {
-				z = fir_32x16(filter, *x0 << 8);
-				*y0 = sat_int24(Q_SHIFT_RND(z, 31, 23));
-				x0 += channels;
-				y0 += channels;
+		max_samples = cir_buf_samples_without_wrap_s32(src, source->buf_end);
+		chunk_samples = MIN(remaining_samples, max_samples);
+		max_samples = cir_buf_samples_without_wrap_s32(dst, sink->buf_end);
+		chunk_samples = MIN(chunk_samples, max_samples);
+		for (channel = 0; channel < channels; channel++) {
+			src_channel = src + channel;
+			dst_channel = dst + channel;
+			filter = &fir[channel];
+			for (sample_index = 0; sample_index < chunk_samples;
+			     sample_index += channels) {
+				filtered_sample = fir_32x16(filter, *src_channel << 8);
+				*dst_channel = sat_int24(Q_SHIFT_RND(filtered_sample, 31, 23));
+				src_channel += channels;
+				dst_channel += channels;
 			}
 		}
-		remaining_samples -= n;
-		x = source_cir_buf_wrap(x + n, source->buf_start, source->buf_end);
-		y = cir_buf_wrap(y + n, sink->buf_start, sink->buf_end);
+		remaining_samples -= chunk_samples;
+		src = source_cir_buf_wrap(src + chunk_samples, source->buf_start, source->buf_end);
+		dst = cir_buf_wrap(dst + chunk_samples, sink->buf_start, sink->buf_end);
 	}
 }
 #endif /* CONFIG_FORMAT_S24LE */
@@ -98,31 +106,35 @@ void eq_fir_s32(struct fir_state_32x16 fir[], struct cir_buf_source *source,
 		struct cir_buf_sink *sink, int frames, int channels)
 {
 	struct fir_state_32x16 *filter;
-	const int32_t *x0;
-	int32_t *y0;
-	const int32_t *x = source->ptr;
-	int32_t *y = sink->ptr;
-	int nmax, n, i, j;
+	const int32_t *src_channel;
+	int32_t *dst_channel;
+	const int32_t *src = source->ptr;
+	int32_t *dst = sink->ptr;
+	int max_samples;
+	int chunk_samples;
+	int sample_index;
+	int channel;
 	int remaining_samples = frames * channels;
 
 	while (remaining_samples) {
-		nmax = cir_buf_samples_without_wrap_s32(x, source->buf_end);
-		n = MIN(remaining_samples, nmax);
-		nmax = cir_buf_samples_without_wrap_s32(y, sink->buf_end);
-		n = MIN(n, nmax);
-		for (j = 0; j < channels; j++) {
-			x0 = x + j;
-			y0 = y + j;
-			filter = &fir[j];
-			for (i = 0; i < n; i += channels) {
-				*y0 = fir_32x16(filter, *x0);
-				x0 += channels;
-				y0 += channels;
+		max_samples = cir_buf_samples_without_wrap_s32(src, source->buf_end);
+		chunk_samples = MIN(remaining_samples, max_samples);
+		max_samples = cir_buf_samples_without_wrap_s32(dst, sink->buf_end);
+		chunk_samples = MIN(chunk_samples, max_samples);
+		for (channel = 0; channel < channels; channel++) {
+			src_channel = src + channel;
+			dst_channel = dst + channel;
+			filter = &fir[channel];
+			for (sample_index = 0; sample_index < chunk_samples;
+			     sample_index += channels) {
+				*dst_channel = fir_32x16(filter, *src_channel);
+				src_channel += channels;
+				dst_channel += channels;
 			}
 		}
-		remaining_samples -= n;
-		x = source_cir_buf_wrap(x + n, source->buf_start, source->buf_end);
-		y = cir_buf_wrap(y + n, sink->buf_start, sink->buf_end);
+		remaining_samples -= chunk_samples;
+		src = source_cir_buf_wrap(src + chunk_samples, source->buf_start, source->buf_end);
+		dst = cir_buf_wrap(dst + chunk_samples, sink->buf_start, sink->buf_end);
 	}
 }
 #endif /* CONFIG_FORMAT_S32LE */