1 files changed, 82 insertions, 0 deletions
diff --git a/gnuradio-core/src/lib/general/gr_fxpt.h b/gnuradio-core/src/lib/general/gr_fxpt.h
new file mode 100644
index 0000000000..fc8432d64b
--- /dev/null
+++ b/gnuradio-core/src/lib/general/gr_fxpt.h
@@ -0,0 +1,82 @@
+/* -*- c++ -*- */
+/*
+ * Copyright 2004 Free Software Foundation, Inc.
+ * 
+ * This file is part of GNU Radio
+ * 
+ * GNU Radio 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 2, or (at your option)
+ * any later version.
+ * 
+ * GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+#ifndef INCLUDED_GR_FXPT_H
+#define INCLUDED_GR_FXPT_H
+
+#include <gr_types.h>
+
+/*!
+ * \brief fixed point sine and cosine and friends.
+ *
+ *   fixed pt	radians
+ *  ---------	--------
+ *   -2**31       -pi
+ *        0         0
+ *  2**31-1        pi - epsilon
+ *
+ */
+class gr_fxpt
+{
+  static const int WORDBITS = 32;
+  static const int NBITS = 10;
+  static const float s_sine_table[1 << NBITS][2];
+  static const float PI = 3.14159265358979323846;
+  static const float TWO_TO_THE_31 = 2147483648.0;
+public:
+
+  static gr_int32
+  float_to_fixed (float x)
+  {
+    return (gr_int32) ((float) x * TWO_TO_THE_31 / PI);
+  }
+
+  static float
+  fixed_to_float (gr_int32 x)
+  {
+    return x * (PI / TWO_TO_THE_31);
+  }
+
+  /*!
+   * \brief Given a fixed point angle x, return float sine (x)
+   */
+  static float
+  sin (gr_int32 x)
+  {
+    gr_uint32 ux = x;
+    int index = ux >> (WORDBITS - NBITS);
+    return s_sine_table[index][0] * (ux >> 1) + s_sine_table[index][1];
+  }
+
+  /*
+   * \brief Given a fixed point angle x, return float cosine (x)
+   */
+  static float
+  cos (gr_int32 x)
+  {
+    gr_uint32 ux = x + 0x40000000;
+    int index = ux >> (WORDBITS - NBITS);
+    return s_sine_table[index][0] * (ux >> 1) + s_sine_table[index][1];
+  }
+
+};
+
+#endif /* INCLUDED_GR_FXPT_H */