Import of the watch repository from Pebble

third_party/ARM/Source/FastMathFunctions/arm_cos_q31.c

@@ -0,0 +1,96 @@
+/* ----------------------------------------------------------------------
+* Copyright (C) 2010-2014 ARM Limited. All rights reserved.
+*
+* $Date:        07. September 2015
+* $Revision:    V.1.4.5 a
+*
+* Project:      CMSIS DSP Library
+* Title:        arm_cos_q31.c
+*
+* Description: Fast cosine calculation for Q31 values.
+*
+* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
+*
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions
+* are met:
+*   - Redistributions of source code must retain the above copyright
+*     notice, this list of conditions and the following disclaimer.
+*   - Redistributions in binary form must reproduce the above copyright
+*     notice, this list of conditions and the following disclaimer in
+*     the documentation and/or other materials provided with the
+*     distribution.
+*   - Neither the name of ARM LIMITED nor the names of its contributors
+*     may be used to endorse or promote products derived from this
+*     software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+* POSSIBILITY OF SUCH DAMAGE.
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+#include "arm_common_tables.h"
+
+/**
+ * @ingroup groupFastMath
+ */
+
+ /**
+ * @addtogroup cos
+ * @{
+ */
+
+/**
+ * @brief Fast approximation to the trigonometric cosine function for Q31 data.
+ * @param[in] x Scaled input value in radians.
+ * @return  cos(x).
+ *
+ * The Q31 input value is in the range [0 +0.9999] and is mapped to a radian
+ * value in the range [0 2*pi).
+ */
+
+q31_t arm_cos_q31(
+  q31_t x)
+{
+  q31_t cosVal;                                  /* Temporary variables for input, output */
+  int32_t index;                                 /* Index variables */
+  q31_t a, b;                                    /* Four nearest output values */
+  q31_t fract;                                   /* Temporary values for fractional values */
+
+  /* add 0.25 (pi/2) to read sine table */
+  x = (uint32_t)x + 0x20000000;
+  if(x < 0)
+  {   /* convert negative numbers to corresponding positive ones */
+      x = (uint32_t)x + 0x80000000;
+  }
+
+  /* Calculate the nearest index */
+  index = (uint32_t)x >> FAST_MATH_Q31_SHIFT;
+
+  /* Calculation of fractional value */
+  fract = (x - (index << FAST_MATH_Q31_SHIFT)) << 9;
+
+  /* Read two nearest values of input value from the sin table */
+  a = sinTable_q31[index];
+  b = sinTable_q31[index+1];
+
+  /* Linear interpolation process */
+  cosVal = (q63_t)(0x80000000-fract)*a >> 32;
+  cosVal = (q31_t)((((q63_t)cosVal << 32) + ((q63_t)fract*b)) >> 32);
+
+  return cosVal << 1;
+}
+
+/**
+ * @} end of cos group
+ */