1 /* ----------------------------------------------------------------------------
2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
4 * $Date: 17. January 2013
7 * Project: CMSIS DSP Library
8 * Title: arm_q31_to_q7.c
10 * Description: Converts the elements of the Q31 vector to Q7 vector.
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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15 * modification, are permitted provided that the following conditions
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27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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39 * ---------------------------------------------------------------------------- */
44 * @ingroup groupSupport
48 * @addtogroup q31_to_x
53 * @brief Converts the elements of the Q31 vector to Q7 vector.
54 * @param[in] *pSrc points to the Q31 input vector
55 * @param[out] *pDst points to the Q7 output vector
56 * @param[in] blockSize length of the input vector
61 * The equation used for the conversion process is:
64 * pDst[n] = (q7_t) pSrc[n] >> 24; 0 <= n < blockSize.
75 q31_t *pIn = pSrc; /* Src pointer */
76 uint32_t blkCnt; /* loop counter */
78 #ifndef ARM_MATH_CM0_FAMILY
80 /* Run the below code for Cortex-M4 and Cortex-M3 */
81 q31_t in1, in2, in3, in4;
82 q7_t out1, out2, out3, out4;
85 blkCnt = blockSize >> 2u;
87 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
88 ** a second loop below computes the remaining 1 to 3 samples. */
91 /* C = (q7_t) A >> 24 */
92 /* convert from q31 to q7 and then store the results in the destination buffer */
98 out1 = (q7_t) (in1 >> 24);
99 out2 = (q7_t) (in2 >> 24);
100 out3 = (q7_t) (in3 >> 24);
101 out4 = (q7_t) (in4 >> 24);
103 *__SIMD32(pDst)++ = __PACKq7(out1, out2, out3, out4);
105 /* Decrement the loop counter */
109 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
110 ** No loop unrolling is used. */
111 blkCnt = blockSize % 0x4u;
115 /* Run the below code for Cortex-M0 */
117 /* Loop over blockSize number of values */
120 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
124 /* C = (q7_t) A >> 24 */
125 /* convert from q31 to q7 and then store the results in the destination buffer */
126 *pDst++ = (q7_t) (*pIn++ >> 24);
128 /* Decrement the loop counter */
135 * @} end of q31_to_x group