arm_sin_cos_f32.c 5.7 KB

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  1. /* ----------------------------------------------------------------------
  2. * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
  3. *
  4. * $Date: 12. March 2014
  5. * $Revision: V1.4.4
  6. *
  7. * Project: CMSIS DSP Library
  8. * Title: arm_sin_cos_f32.c
  9. *
  10. * Description: Sine and Cosine calculation for floating-point values.
  11. *
  12. * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
  13. *
  14. * Redistribution and use in source and binary forms, with or without
  15. * modification, are permitted provided that the following conditions
  16. * are met:
  17. * - Redistributions of source code must retain the above copyright
  18. * notice, this list of conditions and the following disclaimer.
  19. * - Redistributions in binary form must reproduce the above copyright
  20. * notice, this list of conditions and the following disclaimer in
  21. * the documentation and/or other materials provided with the
  22. * distribution.
  23. * - Neither the name of ARM LIMITED nor the names of its contributors
  24. * may be used to endorse or promote products derived from this
  25. * software without specific prior written permission.
  26. *
  27. * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28. * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29. * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  30. * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  31. * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  32. * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  33. * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  34. * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  35. * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  37. * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  38. * POSSIBILITY OF SUCH DAMAGE.
  39. * -------------------------------------------------------------------- */
  40. #include "arm_math.h"
  41. #include "arm_common_tables.h"
  42. /**
  43. * @ingroup groupController
  44. */
  45. /**
  46. * @defgroup SinCos Sine Cosine
  47. *
  48. * Computes the trigonometric sine and cosine values using a combination of table lookup
  49. * and linear interpolation.
  50. * There are separate functions for Q31 and floating-point data types.
  51. * The input to the floating-point version is in degrees while the
  52. * fixed-point Q31 have a scaled input with the range
  53. * [-1 0.9999] mapping to [-180 +180] degrees.
  54. *
  55. * The floating point function also allows values that are out of the usual range. When this happens, the function will
  56. * take extra time to adjust the input value to the range of [-180 180].
  57. *
  58. * The implementation is based on table lookup using 360 values together with linear interpolation.
  59. * The steps used are:
  60. * -# Calculation of the nearest integer table index.
  61. * -# Compute the fractional portion (fract) of the input.
  62. * -# Fetch the value corresponding to \c index from sine table to \c y0 and also value from \c index+1 to \c y1.
  63. * -# Sine value is computed as <code> *psinVal = y0 + (fract * (y1 - y0))</code>.
  64. * -# Fetch the value corresponding to \c index from cosine table to \c y0 and also value from \c index+1 to \c y1.
  65. * -# Cosine value is computed as <code> *pcosVal = y0 + (fract * (y1 - y0))</code>.
  66. */
  67. /**
  68. * @addtogroup SinCos
  69. * @{
  70. */
  71. /**
  72. * @brief Floating-point sin_cos function.
  73. * @param[in] theta input value in degrees
  74. * @param[out] *pSinVal points to the processed sine output.
  75. * @param[out] *pCosVal points to the processed cos output.
  76. * @return none.
  77. */
  78. void arm_sin_cos_f32(
  79. float32_t theta,
  80. float32_t * pSinVal,
  81. float32_t * pCosVal)
  82. {
  83. float32_t fract, in; /* Temporary variables for input, output */
  84. uint16_t indexS, indexC; /* Index variable */
  85. float32_t f1, f2, d1, d2; /* Two nearest output values */
  86. int32_t n;
  87. float32_t findex, Dn, Df, temp;
  88. /* input x is in degrees */
  89. /* Scale the input, divide input by 360, for cosine add 0.25 (pi/2) to read sine table */
  90. in = theta * 0.00277777777778f;
  91. /* Calculation of floor value of input */
  92. n = (int32_t) in;
  93. /* Make negative values towards -infinity */
  94. if(in < 0.0f)
  95. {
  96. n--;
  97. }
  98. /* Map input value to [0 1] */
  99. in = in - (float32_t) n;
  100. /* Calculation of index of the table */
  101. findex = (float32_t) FAST_MATH_TABLE_SIZE * in;
  102. indexS = ((uint16_t)findex) & 0x1ff;
  103. indexC = (indexS + (FAST_MATH_TABLE_SIZE / 4)) & 0x1ff;
  104. /* fractional value calculation */
  105. fract = findex - (float32_t) indexS;
  106. /* Read two nearest values of input value from the cos & sin tables */
  107. f1 = sinTable_f32[indexC+0];
  108. f2 = sinTable_f32[indexC+1];
  109. d1 = -sinTable_f32[indexS+0];
  110. d2 = -sinTable_f32[indexS+1];
  111. Dn = 0.0122718463030f; // delta between the two points (fixed), in this case 2*pi/FAST_MATH_TABLE_SIZE
  112. Df = f2 - f1; // delta between the values of the functions
  113. temp = Dn*(d1 + d2) - 2*Df;
  114. temp = fract*temp + (3*Df - (d2 + 2*d1)*Dn);
  115. temp = fract*temp + d1*Dn;
  116. /* Calculation of cosine value */
  117. *pCosVal = fract*temp + f1;
  118. /* Read two nearest values of input value from the cos & sin tables */
  119. f1 = sinTable_f32[indexS+0];
  120. f2 = sinTable_f32[indexS+1];
  121. d1 = sinTable_f32[indexC+0];
  122. d2 = sinTable_f32[indexC+1];
  123. Df = f2 - f1; // delta between the values of the functions
  124. temp = Dn*(d1 + d2) - 2*Df;
  125. temp = fract*temp + (3*Df - (d2 + 2*d1)*Dn);
  126. temp = fract*temp + d1*Dn;
  127. /* Calculation of sine value */
  128. *pSinVal = fract*temp + f1;
  129. }
  130. /**
  131. * @} end of SinCos group
  132. */