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arm_q15_to_float.c 4.2KB

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  1. /* ----------------------------------------------------------------------------
  2. * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
  3. *
  4. * $Date: 17. January 2013
  5. * $Revision: V1.4.1
  6. *
  7. * Project: CMSIS DSP Library
  8. * Title: arm_q15_to_float.c
  9. *
  10. * Description: Converts the elements of the Q15 vector to floating-point vector.
  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. /**
  42. * @ingroup groupSupport
  43. */
  44. /**
  45. * @defgroup q15_to_x Convert 16-bit Integer value
  46. */
  47. /**
  48. * @addtogroup q15_to_x
  49. * @{
  50. */
  51. /**
  52. * @brief Converts the elements of the Q15 vector to floating-point vector.
  53. * @param[in] *pSrc points to the Q15 input vector
  54. * @param[out] *pDst points to the floating-point output vector
  55. * @param[in] blockSize length of the input vector
  56. * @return none.
  57. *
  58. * \par Description:
  59. *
  60. * The equation used for the conversion process is:
  61. *
  62. * <pre>
  63. * pDst[n] = (float32_t) pSrc[n] / 32768; 0 <= n < blockSize.
  64. * </pre>
  65. *
  66. */
  67. void arm_q15_to_float(
  68. q15_t * pSrc,
  69. float32_t * pDst,
  70. uint32_t blockSize)
  71. {
  72. q15_t *pIn = pSrc; /* Src pointer */
  73. uint32_t blkCnt; /* loop counter */
  74. #ifndef ARM_MATH_CM0_FAMILY
  75. /* Run the below code for Cortex-M4 and Cortex-M3 */
  76. /*loop Unrolling */
  77. blkCnt = blockSize >> 2u;
  78. /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
  79. ** a second loop below computes the remaining 1 to 3 samples. */
  80. while(blkCnt > 0u)
  81. {
  82. /* C = (float32_t) A / 32768 */
  83. /* convert from q15 to float and then store the results in the destination buffer */
  84. *pDst++ = ((float32_t) * pIn++ / 32768.0f);
  85. *pDst++ = ((float32_t) * pIn++ / 32768.0f);
  86. *pDst++ = ((float32_t) * pIn++ / 32768.0f);
  87. *pDst++ = ((float32_t) * pIn++ / 32768.0f);
  88. /* Decrement the loop counter */
  89. blkCnt--;
  90. }
  91. /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  92. ** No loop unrolling is used. */
  93. blkCnt = blockSize % 0x4u;
  94. #else
  95. /* Run the below code for Cortex-M0 */
  96. /* Loop over blockSize number of values */
  97. blkCnt = blockSize;
  98. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  99. while(blkCnt > 0u)
  100. {
  101. /* C = (float32_t) A / 32768 */
  102. /* convert from q15 to float and then store the results in the destination buffer */
  103. *pDst++ = ((float32_t) * pIn++ / 32768.0f);
  104. /* Decrement the loop counter */
  105. blkCnt--;
  106. }
  107. }
  108. /**
  109. * @} end of q15_to_x group
  110. */