From b236757ac4ae678d7f762e1d7cabb18ca22486fc Mon Sep 17 00:00:00 2001
From: Paul Brossier <piem@piem.org>
Date: Wed, 8 Aug 2018 17:03:35 +0200
Subject: [PATCH] src/spectral/dct_plain.c: add plain dct

---
 src/spectral/dct_plain.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 src/spectral/dct_plain.c

diff --git a/src/spectral/dct_plain.c b/src/spectral/dct_plain.c
new file mode 100644
index 00000000..0756f5cd
--- /dev/null
+++ b/src/spectral/dct_plain.c
@@ -0,0 +1,93 @@
+/*
+  Copyright (C) 2018 Paul Brossier <piem@aubio.org>
+
+  This file is part of aubio.
+
+  aubio is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  aubio is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with aubio.  If not, see <http://www.gnu.org/licenses/>.
+
+*/
+
+#include "aubio_priv.h"
+#include "fvec.h"
+#include "fmat.h"
+#include "spectral/dct.h"
+
+typedef struct _aubio_dct_plain_t aubio_dct_plain_t;
+
+struct _aubio_dct_plain_t {
+  uint_t size;
+  fmat_t *dct_coeffs;       /** DCT type II orthonormal transform, size * size */
+  fmat_t *idct_coeffs;      /** DCT type III orthonormal transform, size * size */
+};
+
+aubio_dct_plain_t * new_aubio_dct_plain (uint_t size) {
+  aubio_dct_plain_t * s = AUBIO_NEW(aubio_dct_plain_t);
+  uint_t i, j;
+  smpl_t scaling;
+  if (aubio_is_power_of_two (size) == 1 && size > 16) {
+    AUBIO_WRN("dct_plain: using plain dct but size %d is a power of two", size);
+  }
+
+  s->size = size;
+
+  s->dct_coeffs = new_fmat (size, size);
+  s->idct_coeffs = new_fmat (size, size);
+
+  /* compute DCT type-II transformation matrix
+     dct_coeffs[j][i] = cos ( j * (i+.5) * PI / n_filters )
+  */
+  scaling = SQRT (2. / size);
+  for (i = 0; i < size; i++) {
+    for (j = 1; j < size; j++) {
+      s->dct_coeffs->data[j][i] =
+          scaling * COS (j * (i + 0.5) * PI / size );
+    }
+    s->dct_coeffs->data[0][i] = 1. / SQRT (size);
+  }
+
+  /* compute DCT type-III transformation matrix
+     idct_coeffs[j][i] = cos ( i * (j+.5) * PI / n_filters )
+  */
+  scaling = SQRT (2. / size);
+  for (j = 0; j < size; j++) {
+    for (i = 1; i < size; i++) {
+      s->idct_coeffs->data[j][i] =
+          scaling * COS (i * (j + 0.5) * PI / size );
+    }
+    s->idct_coeffs->data[j][0] = 1. / SQRT (size);
+  }
+  return s;
+}
+
+void del_aubio_dct_plain (aubio_dct_plain_t *s) {
+  del_fmat(s->dct_coeffs);
+  del_fmat(s->idct_coeffs);
+  AUBIO_FREE(s);
+}
+
+void aubio_dct_plain_do(aubio_dct_plain_t *s, const fvec_t *input, fvec_t *output) {
+  if (input->length != output->length || input->length != s->size) {
+    AUBIO_WRN("dct_plain: using input length %d, but output length = %d and size = %d",
+        input->length, output->length, s->size);
+  }
+  fmat_vecmul(s->dct_coeffs, input, output);
+}
+
+void aubio_dct_plain_rdo(aubio_dct_plain_t *s, const fvec_t *input, fvec_t *output) {
+  if (input->length != output->length || input->length != s->size) {
+    AUBIO_WRN("dct_plain: using input length %d, but output length = %d and size = %d",
+        input->length, output->length, s->size);
+  }
+  fmat_vecmul(s->idct_coeffs, input, output);
+}
-- 
2.11.0