Take 2 at 'Consolidate all fixed point math routines in one library' (FS#10400) by Jeffrey Goode

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21664 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 69 insertions, 0 deletions

diff --git a/apps/fixedpoint.h b/apps/fixedpoint.h
new file mode 100644
index 0000000000..49292f3417
--- /dev/null
+++ b/apps/fixedpoint.h
@@ -0,0 +1,69 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id: fixedpoint.h -1   $
+ *
+ * Copyright (C) 2006 Jens Arnold
+ *
+ * Fixed point library for plugins
+ *
+ * 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 software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+/** APPS - FIXED POINT MATH ROUTINES - USAGE
+ *
+ *  - x and y arguments are fixed point integers
+ *  - fracbits is the number of fractional bits in the argument(s)
+ *  - functions return long fixed point integers with the specified number
+ *    of fractional bits unless otherwise specified
+ *
+ *  Multiply two fixed point numbers:
+ *      fp_mul(x, y, fracbits)
+ *
+ *  Divide two fixed point numbers:
+ *      fp_div(x, y, fracbits)
+ *
+ *  Calculate decibel equivalent of a gain factor:
+ *      fp_decibels(factor, fracbits)
+ *          where fracbits is in the range 12 to 22 (higher is better),
+ *          and factor is a positive fixed point integer.
+ *
+ *  Calculate factor equivalent of a decibel value:
+ *      fp_factor(decibels, fracbits)
+ *          where fracbits is in the range 12 to 22 (lower is better),
+ *          and decibels is a fixed point integer.
+ */
+
+#ifndef _FIXEDPOINT_H_APPS
+#define _FIXEDPOINT_H_APPS
+
+#define fp_mul(x, y, z) (long)((((long long)(x)) * ((long long)(y))) >> (z))
+#define fp_div(x, y, z) (long)((((long long)(x)) << (z)) / ((long long)(y)))
+
+
+/** TAKEN FROM ORIGINAL fixedpoint.h */
+long fp_sincos(unsigned long phase, long *cos);
+
+
+/** MODIFIED FROM replaygain.c */
+#define FP_INF          (0x7fffffff)
+#define FP_NEGINF      -(0x7fffffff)
+
+/* fracbits in range 12 - 22 work well. Higher is better for
+ * calculating dB, lower is better for calculating ratio.
+ */
+/* long fp_decibels(unsigned long factor, unsigned int fracbits); */
+long fp_factor(long decibels, unsigned int fracbits);
+
+#endif