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Diffstat (limited to 'digital/avr/modules/math/fixed/fixed_cosin_f824.c')
-rw-r--r--digital/avr/modules/math/fixed/fixed_cosin_f824.c81
1 files changed, 81 insertions, 0 deletions
diff --git a/digital/avr/modules/math/fixed/fixed_cosin_f824.c b/digital/avr/modules/math/fixed/fixed_cosin_f824.c
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+++ b/digital/avr/modules/math/fixed/fixed_cosin_f824.c
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+/* fixed_cosin_f824.c */
+/* avr.math.fixed - Fixed point math module. {{{
+ *
+ * Copyright (C) 2005 Nicolas Schodet
+ *
+ * Robot APB Team/Efrei 2006.
+ * Web: http://assos.efrei.fr/robot/
+ * Email: robot AT efrei DOT fr
+ *
+ * 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.
+ *
+ * }}} */
+#include "common.h"
+#include "fixed.h"
+
+/** Compute cosinus for angles between [0,pi/2]. */
+static int32_t
+fixed_cos_dli (int32_t a)
+{
+ static const int32_t f[] = {
+ (1L << 24) * -26.42625678337439745096,
+ (1L << 24) * 60.24464137187666035919,
+ (1L << 24) * -85.45681720669372773226,
+ (1L << 24) * 64.93939402266829148905,
+ (1L << 24) * -19.73920880217871723738,
+ (1L << 24) * 1
+ };
+ int32_t r;
+ int32_t a2;
+ uint8_t i;
+ a2 = fixed_mul_f824 (a, a);
+ r = f[0];
+ for (i = 1; i < sizeof (f) / sizeof (f[0]); i++)
+ r = fixed_mul_f824 (r, a2) + f[i];
+ return r;
+}
+
+/** Compute cosinus, angle f8.24, result f8.24. */
+int32_t
+fixed_cos_f824 (int32_t a)
+{
+ a &= (1L << 24) - 1;
+ uint8_t z = ((uint32_t) a >> 16) & 0xc0;
+ if (z == 0)
+ return fixed_cos_dli (a);
+ else if (z == 1 << 6)
+ return -fixed_cos_dli ((1L << 23) - a);
+ else if (z == 2 << 6)
+ return -fixed_cos_dli (a & 0xff7fffff);
+ else
+ return fixed_cos_dli ((1L << 24) - a);
+}
+
+/** Compute sinus, angle f8.24, result f8.24. */
+int32_t
+fixed_sin_f824 (int32_t a)
+{
+ a &= (1L << 24) - 1;
+ uint8_t z = ((uint32_t) a >> 16) & 0xc0;
+ if (z == 0)
+ return fixed_cos_dli ((1L << 22) - a);
+ else if (z == 1 << 6)
+ return fixed_cos_dli (a - (1L << 22));
+ else if (z == 2 << 6)
+ return -fixed_cos_dli ((1L << 23) + (1L << 22) - a);
+ else
+ return -fixed_cos_dli (a - (1L << 23) - (1L << 22));
+}
+