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arm_float_to_q15.c 6.1KB

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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_float_to_q15.c
  9. *
  10. * Description: Converts the elements of the floating-point vector to Q15 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. * @addtogroup float_to_x
  46. * @{
  47. */
  48. /**
  49. * @brief Converts the elements of the floating-point vector to Q15 vector.
  50. * @param[in] *pSrc points to the floating-point input vector
  51. * @param[out] *pDst points to the Q15 output vector
  52. * @param[in] blockSize length of the input vector
  53. * @return none.
  54. *
  55. * \par Description:
  56. * \par
  57. * The equation used for the conversion process is:
  58. * <pre>
  59. * pDst[n] = (q15_t)(pSrc[n] * 32768); 0 <= n < blockSize.
  60. * </pre>
  61. * \par Scaling and Overflow Behavior:
  62. * \par
  63. * The function uses saturating arithmetic.
  64. * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
  65. * \note
  66. * In order to apply rounding, the library should be rebuilt with the ROUNDING macro
  67. * defined in the preprocessor section of project options.
  68. *
  69. */
  70. void arm_float_to_q15(
  71. float32_t * pSrc,
  72. q15_t * pDst,
  73. uint32_t blockSize)
  74. {
  75. float32_t *pIn = pSrc; /* Src pointer */
  76. uint32_t blkCnt; /* loop counter */
  77. #ifdef ARM_MATH_ROUNDING
  78. float32_t in;
  79. #endif /* #ifdef ARM_MATH_ROUNDING */
  80. #ifndef ARM_MATH_CM0_FAMILY
  81. /* Run the below code for Cortex-M4 and Cortex-M3 */
  82. /*loop Unrolling */
  83. blkCnt = blockSize >> 2u;
  84. /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
  85. ** a second loop below computes the remaining 1 to 3 samples. */
  86. while(blkCnt > 0u)
  87. {
  88. #ifdef ARM_MATH_ROUNDING
  89. /* C = A * 32768 */
  90. /* convert from float to q15 and then store the results in the destination buffer */
  91. in = *pIn++;
  92. in = (in * 32768.0f);
  93. in += in > 0 ? 0.5 : -0.5;
  94. *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  95. in = *pIn++;
  96. in = (in * 32768.0f);
  97. in += in > 0 ? 0.5 : -0.5;
  98. *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  99. in = *pIn++;
  100. in = (in * 32768.0f);
  101. in += in > 0 ? 0.5 : -0.5;
  102. *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  103. in = *pIn++;
  104. in = (in * 32768.0f);
  105. in += in > 0 ? 0.5 : -0.5;
  106. *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  107. #else
  108. /* C = A * 32768 */
  109. /* convert from float to q15 and then store the results in the destination buffer */
  110. *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  111. *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  112. *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  113. *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  114. #endif /* #ifdef ARM_MATH_ROUNDING */
  115. /* Decrement the loop counter */
  116. blkCnt--;
  117. }
  118. /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
  119. ** No loop unrolling is used. */
  120. blkCnt = blockSize % 0x4u;
  121. while(blkCnt > 0u)
  122. {
  123. #ifdef ARM_MATH_ROUNDING
  124. /* C = A * 32768 */
  125. /* convert from float to q15 and then store the results in the destination buffer */
  126. in = *pIn++;
  127. in = (in * 32768.0f);
  128. in += in > 0 ? 0.5 : -0.5;
  129. *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  130. #else
  131. /* C = A * 32768 */
  132. /* convert from float to q15 and then store the results in the destination buffer */
  133. *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  134. #endif /* #ifdef ARM_MATH_ROUNDING */
  135. /* Decrement the loop counter */
  136. blkCnt--;
  137. }
  138. #else
  139. /* Run the below code for Cortex-M0 */
  140. /* Loop over blockSize number of values */
  141. blkCnt = blockSize;
  142. while(blkCnt > 0u)
  143. {
  144. #ifdef ARM_MATH_ROUNDING
  145. /* C = A * 32768 */
  146. /* convert from float to q15 and then store the results in the destination buffer */
  147. in = *pIn++;
  148. in = (in * 32768.0f);
  149. in += in > 0 ? 0.5f : -0.5f;
  150. *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
  151. #else
  152. /* C = A * 32768 */
  153. /* convert from float to q15 and then store the results in the destination buffer */
  154. *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
  155. #endif /* #ifdef ARM_MATH_ROUNDING */
  156. /* Decrement the loop counter */
  157. blkCnt--;
  158. }
  159. #endif /* #ifndef ARM_MATH_CM0_FAMILY */
  160. }
  161. /**
  162. * @} end of float_to_x group
  163. */