1 files changed, 77 insertions, 0 deletions
diff --git a/gr-blocks/lib/gen_sine_table.py b/gr-blocks/lib/gen_sine_table.py
new file mode 100755
index 0000000000..d7d11eff11
--- /dev/null
+++ b/gr-blocks/lib/gen_sine_table.py
@@ -0,0 +1,77 @@
+#!/usr/bin/env python
+#
+# 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 3, 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., 51 Franklin Street,
+# Boston, MA 02110-1301, USA.
+#
+
+import math
+import sys
+
+def wrap (x):
+    if x >= 2**31:
+        return x - 2**32
+    return x
+
+def gen_approx_table (f, nentries, min_x, max_x):
+    """return a list of nentries containing tuples of the form:
+    (m, c, abs_error).  min_x and max_x specify the domain
+    of the table.
+    """
+    r = []
+    incx = float (max_x - min_x) / nentries
+    for i in range (nentries):
+        a = (i * incx) + min_x
+        b = ((i + 1) * incx) + min_x
+        m = (f(b)-f(a))/(b-a)
+        c = (3*a+b)*(f(a)-f(b))/(4*(b-a)) + (f((a+b)/2) + f(a))/2
+        abs_error = c+m*a-f(a)
+        r.append ((m, c, abs_error))
+    return r
+
+def scaled_sine (x):
+    return math.sin (x * math.pi / 2**31)
+
+def gen_sine_table ():
+    nbits = 10
+    nentries = 2**nbits
+
+    # min_x = -2**31
+    # max_x =  2**31-1
+    min_x = 0
+    max_x = 2**32-1
+    t = gen_approx_table (scaled_sine, nentries, min_x, max_x)
+
+    max_error = 0
+    for e in t:
+        max_error = max (max_error, abs (e[2]))
+
+    # sys.stdout.write ('static const int WORDBITS = 32;\n')
+    # sys.stdout.write ('static const int NBITS = %d;\n' % (nbits,))
+
+    sys.stdout.write ('  // max_error = %22.15e\n' % (max_error,))
+
+    # sys.stdout.write ('static const double sine_table[%d][2] = {\n'% (nentries,))
+
+    for e in t:
+        sys.stdout.write ('  { %22.15e, %22.15e },\n' % (2 * e[0], e[1]))
+
+    # sys.stdout.write ('};\n')
+
+if __name__ == '__main__':
+    gen_sine_table ()