Diff: fixed.cpp

Revision:

0:7627c79db971

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/fixed.cpp	Fri Nov 26 12:18:30 2010 +0000
@@ -0,0 +1,79 @@
+/*
+ * libmad - MPEG audio decoder library
+ * Copyright (C) 2000-2004 Underbit Technologies, Inc.
+ *
+ * This program 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 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * $Id: fixed.c,v 1.1 2010/11/23 20:12:57 andy Exp $
+ */
+
+#  include "config.h"
+
+# include "global.h"
+
+# include "fixed.h"
+
+/*
+ * NAME:	fixed->abs()
+ * DESCRIPTION:	return absolute value of a fixed-point number
+ */
+mad_fixed_t mad_f_abs(mad_fixed_t x)
+{
+  return x < 0 ? -x : x;
+}
+
+/*
+ * NAME:	fixed->div()
+ * DESCRIPTION:	perform division using fixed-point math
+ */
+mad_fixed_t mad_f_div(mad_fixed_t x, mad_fixed_t y)
+{
+  mad_fixed_t q, r;
+  unsigned int bits;
+
+  q = mad_f_abs(x / y);
+
+  if (x < 0) {
+    x = -x;
+    y = -y;
+  }
+
+  r = x % y;
+
+  if (y < 0) {
+    x = -x;
+    y = -y;
+  }
+
+  if (q > mad_f_intpart(MAD_F_MAX) &&
+      !(q == -mad_f_intpart(MAD_F_MIN) && r == 0 && (x < 0) != (y < 0)))
+    return 0;
+
+  for (bits = MAD_F_FRACBITS; bits && r; --bits) {
+    q <<= 1, r <<= 1;
+    if (r >= y)
+      r -= y, ++q;
+  }
+
+  /* round */
+  if (2 * r >= y)
+    ++q;
+
+  /* fix sign */
+  if ((x < 0) != (y < 0))
+    q = -q;
+
+  return q << bits;
+}