libxwax: Exchange the static delayline with a generic ringbuffer

This ringbuffer is more versatile and can also be used for later filter
implementations.

Author: jclsn

CMakeLists.txt

@@ -5157,7 +5157,7 @@ if(VINYLCONTROL)
       lib/xwax/lut.c
       lib/xwax/lut_mk2.c
       lib/xwax/filters.c
-      lib/xwax/delayline.c
+      lib/xwax/ringbuffer.c
       lib/xwax/pitch_kalman.c
   )
   target_include_directories(mixxx-xwax SYSTEM PUBLIC lib/xwax)

lib/xwax/delayline.c

@@ -0,0 +1,132 @@
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "ringbuffer.h"
+
+/*
+ * Allocates the ringbuffer
+ */
+
+struct ringbuffer *rb_alloc(size_t size, size_t elem_size)
+{
+	if (!size || !elem_size) {
+		errno = EINVAL;
+		perror(__func__);
+		return NULL;
+	}
+
+	struct ringbuffer *rb = malloc(sizeof(struct ringbuffer));
+	if (!rb)
+		goto error;
+
+	rb->size = size;
+	rb->elem_size = elem_size;
+	rb->current = size - 1;
+
+	rb->data = calloc(size, elem_size);
+	if (!rb->data)
+		goto error_data;
+
+	return rb;
+
+error_data:
+		free(rb);
+error:
+		perror(__func__);
+
+		return NULL;
+}
+
+/*
+ * Initializes the ringbuffer
+ */
+
+void rb_destroy(struct ringbuffer *rb)
+{
+	if (!rb)
+		return;
+
+	if (rb->data) {
+		rb_reset(rb);
+		free(rb->data);
+		rb->data = NULL;
+	}
+
+	free(rb);
+	rb = NULL;
+}
+
+/*
+ * Gets the sample at index i in the ringbuffer
+ */
+
+void *rb_at(const struct ringbuffer *rb, ptrdiff_t i)
+{
+	if (!rb || !rb->data || rb->size == 0) {
+		errno = EINVAL;
+		perror(__func__);
+		return NULL;
+	}
+
+	ptrdiff_t index = (rb->current + i) % rb->size;
+	if (index < 0)
+		index += rb->size;
+
+	/* Offset from the start in bytes: index * sizeof(element) */
+
+	return (char *)rb->data + index * rb->elem_size;
+}
+
+/*
+ * Decrements the ringbuffer pointer
+ */
+
+static inline void rb_dec(struct ringbuffer *rb)
+{
+	if (!rb || rb->size == 0) {
+		errno = EINVAL;
+		perror(__func__);
+		return;
+	}
+
+	rb->current--;
+	if (rb->current < 0)
+		rb->current += rb->size;
+}
+
+/*
+ * Pushes a new sample to the ringbuffer
+ */
+
+void rb_push(struct ringbuffer *rb, const void *elem)
+{
+	if (!rb || !rb->data) {
+		errno = EINVAL;
+		perror(__func__);
+		return;
+	}
+
+	rb_dec(rb);
+
+	/* Compute the destination pointer as an offset in bytes from the start of the buffer */
+
+	memcpy((char *)rb->data + rb->current * rb->elem_size, elem, rb->elem_size);
+}
+
+/*
+ * Fills the ringbuffer data with zeros and resets the pointer
+ */
+
+void rb_reset(struct ringbuffer *rb)
+{
+	if (!rb || !rb->data) {
+		errno = EINVAL;
+		perror(__func__);
+		return;
+	}
+
+	rb->current = rb->size - 1;
+	memset(rb->data, 0, rb->size * rb->elem_size);
+}

lib/xwax/delayline.h

@@ -0,0 +1,21 @@
+#ifndef RINGBUFFER_H
+
+#define RINGBUFFER_H
+
+#include <stddef.h>
+
+struct ringbuffer {
+	size_t size;
+	size_t elem_size;
+	void *data;
+	ptrdiff_t current;
+};
+
+struct ringbuffer *rb_alloc(size_t size, size_t elem_size);
+void rb_destroy(struct ringbuffer *rb);
+void rb_reset(struct ringbuffer *rb);
+
+void *rb_at(const struct ringbuffer *rb, ptrdiff_t i);
+void rb_push(struct ringbuffer *rb, const void *elem);
+
+#endif /* end of include guard RINGBUFFER_H */

lib/xwax/ringbuffer.c

@@ -380,7 +380,9 @@ void mk2_subcode_init(struct mk2_subcode *sc)
     sc->avg_slope = INT_MAX/2;
     sc->bit = U128_ZERO;
 
-    delayline_init(&sc->readings);
+    sc->readings = rb_alloc(5, sizeof(int));
+    assert(sc->readings);
+
 
     /* Initialise smoothing filters */
     ema_init(&sc->ema_reading, 0.01);
@@ -397,7 +399,8 @@ static void init_mk2_channel(struct timecoder_channel *ch)
     ch->mk2.rms = INT_MAX/2;
     ch->mk2.rms_deriv = 0;
 
-    delayline_init(&ch->mk2.delayline);
+    ch->mk2.delayline = rb_alloc(5, sizeof(int));
+    assert(ch->mk2.delayline );
 
     ema_init(&ch->mk2.ema_filter, 3e-1);
     derivative_init(&ch->mk2.differentiator);
@@ -495,10 +498,10 @@ void timecoder_clear(struct timecoder *tc)
     assert(tc->mon == NULL);
 
     if (tc->def->flags & TRAKTOR_MK2) {
-        delayline_init(&tc->primary.mk2.delayline);
-        delayline_init(&tc->secondary.mk2.delayline);
-        delayline_init(&tc->upper_bitstream.readings);
-        delayline_init(&tc->lower_bitstream.readings);
+        rb_destroy(tc->primary.mk2.delayline);
+        rb_destroy(tc->secondary.mk2.delayline);
+        rb_destroy(tc->upper_bitstream.readings);
+        rb_destroy(tc->lower_bitstream.readings);
     }
 }
 
@@ -783,7 +786,7 @@ static void process_sample(struct timecoder *tc,
     if (tc->def->flags & TRAKTOR_MK2) {
         if (tc->secondary.swapped)
         {
-            int reading = *delayline_at(&tc->secondary.mk2.delayline, 3);
+            int reading = *(int*)rb_at(tc->secondary.mk2.delayline, 3);
             mk2_process_timecode(tc, reading);
         }
     } else {

lib/xwax/ringbuffer.h

@@ -27,7 +27,7 @@
 #include "lut_mk2.h"
 #include "pitch.h"
 #include "pitch_kalman.h"
-#include "delayline.h"
+#include "ringbuffer.h"
 
 #define TIMECODER_CHANNELS 2
 
@@ -58,7 +58,7 @@ struct timecoder_channel_mk2 {
     int rms, rms_deriv; /* RMS values for the signal and its derivative */
     signed int deriv, deriv_scaled; /* Derivative and its scaled version */
 
-    struct delayline delayline; /* needed for the Traktor MK2 demodulation */
+    struct ringbuffer *delayline; /* needed for the Traktor MK2 demodulation */
     struct ema_filter ema_filter;
     struct differentiator differentiator;
     struct root_mean_square rms_filter, rms_deriv_filter;
@@ -83,7 +83,7 @@ struct mk2_subcode {
     signed int avg_slope;
     bool recent_bit_flip;
 
-    struct delayline readings;
+    struct ringbuffer *readings;
     struct ema_filter ema_reading;
     struct ema_filter ema_slope;
 };