1 /* ----------------------------------------------------------------------------
2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
4 * $Date: 17. January 2013
7 * Project: CMSIS DSP Library
8 * Title: arm_float_to_q15.c
10 * Description: Converts the elements of the floating-point vector to Q15 vector.
12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
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
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.
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;
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35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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38 * POSSIBILITY OF SUCH DAMAGE.
39 * ---------------------------------------------------------------------------- */
44 * @ingroup groupSupport
48 * @addtogroup float_to_x
53 * @brief Converts the elements of the floating-point vector to Q15 vector.
54 * @param[in] *pSrc points to the floating-point input vector
55 * @param[out] *pDst points to the Q15 output vector
56 * @param[in] blockSize length of the input vector
61 * The equation used for the conversion process is:
63 * pDst[n] = (q15_t)(pSrc[n] * 32768); 0 <= n < blockSize.
65 * \par Scaling and Overflow Behavior:
67 * The function uses saturating arithmetic.
68 * Results outside of the allowable Q15 range [0x8000 0x7FFF] will be saturated.
70 * In order to apply rounding, the library should be rebuilt with the ROUNDING macro
71 * defined in the preprocessor section of project options.
76 void arm_float_to_q15(
81 float32_t *pIn = pSrc; /* Src pointer */
82 uint32_t blkCnt; /* loop counter */
84 #ifdef ARM_MATH_ROUNDING
88 #endif /* #ifdef ARM_MATH_ROUNDING */
90 #ifndef ARM_MATH_CM0_FAMILY
92 /* Run the below code for Cortex-M4 and Cortex-M3 */
95 blkCnt = blockSize >> 2u;
97 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
98 ** a second loop below computes the remaining 1 to 3 samples. */
102 #ifdef ARM_MATH_ROUNDING
104 /* convert from float to q15 and then store the results in the destination buffer */
106 in = (in * 32768.0f);
107 in += in > 0 ? 0.5 : -0.5;
108 *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
111 in = (in * 32768.0f);
112 in += in > 0 ? 0.5 : -0.5;
113 *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
116 in = (in * 32768.0f);
117 in += in > 0 ? 0.5 : -0.5;
118 *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
121 in = (in * 32768.0f);
122 in += in > 0 ? 0.5 : -0.5;
123 *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
128 /* convert from float to q15 and then store the results in the destination buffer */
129 *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
130 *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
131 *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
132 *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
134 #endif /* #ifdef ARM_MATH_ROUNDING */
136 /* Decrement the loop counter */
140 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
141 ** No loop unrolling is used. */
142 blkCnt = blockSize % 0x4u;
147 #ifdef ARM_MATH_ROUNDING
149 /* convert from float to q15 and then store the results in the destination buffer */
151 in = (in * 32768.0f);
152 in += in > 0 ? 0.5 : -0.5;
153 *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
158 /* convert from float to q15 and then store the results in the destination buffer */
159 *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
161 #endif /* #ifdef ARM_MATH_ROUNDING */
163 /* Decrement the loop counter */
170 /* Run the below code for Cortex-M0 */
172 /* Loop over blockSize number of values */
178 #ifdef ARM_MATH_ROUNDING
180 /* convert from float to q15 and then store the results in the destination buffer */
182 in = (in * 32768.0f);
183 in += in > 0 ? 0.5f : -0.5f;
184 *pDst++ = (q15_t) (__SSAT((q31_t) (in), 16));
189 /* convert from float to q15 and then store the results in the destination buffer */
190 *pDst++ = (q15_t) __SSAT((q31_t) (*pIn++ * 32768.0f), 16);
192 #endif /* #ifdef ARM_MATH_ROUNDING */
194 /* Decrement the loop counter */
198 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
203 * @} end of float_to_x group