From 3fcf463f9ef42aa0da0da4f9d0aed2e7aeda28bb Mon Sep 17 00:00:00 2001
From: Sebastian Gesemann <unknown>
Date: Mon, 3 Oct 2011 12:03:37 +0200
Subject: import dsd2pcm_src.zip

[this is the code from dsd2pcm_src.zip, published on a forum by
Sebastian Gesemann.  Upon request, he has given permission to
redistribute and modify his code, without referring to a specific
license. - mk]
---
 src/dsd2pcm/noiseshape.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 src/dsd2pcm/noiseshape.c

(limited to 'src/dsd2pcm/noiseshape.c')

diff --git a/src/dsd2pcm/noiseshape.c b/src/dsd2pcm/noiseshape.c
new file mode 100644
index 000000000..ecd2f251d
--- /dev/null
+++ b/src/dsd2pcm/noiseshape.c
@@ -0,0 +1,83 @@
+#include <stdlib.h>
+#include <string.h>
+
+#include "noiseshape.h"
+
+extern int noise_shape_init(
+	noise_shape_ctx *ctx,
+	int sos_count,
+	const float *coeffs)
+{
+	int i;
+	ctx->sos_count = sos_count;
+	ctx->bbaa = coeffs;
+	ctx->t1 = (float*) malloc(sizeof(float)*sos_count);
+	if (!ctx->t1) goto escape1;
+	ctx->t2 = (float*) malloc(sizeof(float)*sos_count);
+	if (!ctx->t2) goto escape2;
+	for (i=0; i<sos_count; ++i) {
+		ctx->t1[i] = 0.f;
+		ctx->t2[i] = 0.f;
+	}
+	return 0;
+escape2:
+	free(ctx->t1);
+escape1:
+	return -1;
+}
+
+extern void noise_shape_destroy(
+	noise_shape_ctx *ctx)
+{
+	free(ctx->t1);
+	free(ctx->t2);
+}
+
+extern int noise_shape_clone(
+	const noise_shape_ctx *from,
+	noise_shape_ctx *to)
+{
+	to->sos_count = from->sos_count;
+	to->bbaa = from->bbaa;
+	to->t1 = (float*) malloc(sizeof(float)*to->sos_count);
+	if (!to->t1) goto error1;
+	to->t2 = (float*) malloc(sizeof(float)*to->sos_count);
+	if (!to->t2) goto error2;
+	memcpy(to->t1,from->t1,sizeof(float)*to->sos_count);
+	memcpy(to->t2,from->t2,sizeof(float)*to->sos_count);
+	return 0;
+error2:
+	free(to->t1);
+error1:
+	return -1;
+}
+
+extern float noise_shape_get(noise_shape_ctx *ctx)
+{
+	int i;
+	float acc;
+	const float *c;
+	acc = 0.0;
+	c = ctx->bbaa;
+	for (i=0; i<ctx->sos_count; ++i) {
+		float t1i = ctx->t1[i];
+		float t2i = ctx->t2[i];
+		ctx->t2[i] = acc -= t1i * c[2] + t2i * c[3];
+		acc += t1i * c[0] + t2i * c[1];
+		c += 4;
+	}
+	return acc;
+}
+
+extern void noise_shape_update(noise_shape_ctx *ctx, float qerror)
+{
+	float *p;
+	int i;
+	for (i=0; i<ctx->sos_count; ++i) {
+		ctx->t2[i] += qerror;
+	}
+	p = ctx->t1;
+	ctx->t1 = ctx->t2;
+	ctx->t2 = p;
+}
+
-- 
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