1 /* ----------------------------------------------------------------------
2 * Copyright (C) 2010-2013 ARM Limited. All rights reserved.
4 * $Date: 17. January 2013
7 * Project: CMSIS DSP Library
10 * Description: Q7 vector absolute value.
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
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39 * -------------------------------------------------------------------- */
48 * @addtogroup BasicAbs
53 * @brief Q7 vector absolute value.
54 * @param[in] *pSrc points to the input buffer
55 * @param[out] *pDst points to the output buffer
56 * @param[in] blockSize number of samples in each vector
59 * \par Conditions for optimum performance
60 * Input and output buffers should be aligned by 32-bit
63 * <b>Scaling and Overflow Behavior:</b>
65 * The function uses saturating arithmetic.
66 * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.
74 uint32_t blkCnt; /* loop counter */
75 q7_t in; /* Input value1 */
77 #ifndef ARM_MATH_CM0_FAMILY
79 /* Run the below code for Cortex-M4 and Cortex-M3 */
80 q31_t in1, in2, in3, in4; /* temporary input variables */
81 q31_t out1, out2, out3, out4; /* temporary output variables */
84 blkCnt = blockSize >> 2u;
86 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
87 ** a second loop below computes the remaining 1 to 3 samples. */
93 in2 = (q31_t) * (pSrc + 1);
94 in3 = (q31_t) * (pSrc + 2);
96 /* find absolute value */
97 out1 = (in1 > 0) ? in1 : (q31_t)__QSUB8(0, in1);
100 in4 = (q31_t) * (pSrc + 3);
102 /* find absolute value */
103 out2 = (in2 > 0) ? in2 : (q31_t)__QSUB8(0, in2);
105 /* store result to destination */
108 /* find absolute value */
109 out3 = (in3 > 0) ? in3 : (q31_t)__QSUB8(0, in3);
111 /* find absolute value */
112 out4 = (in4 > 0) ? in4 : (q31_t)__QSUB8(0, in4);
114 /* store result to destination */
115 *(pDst + 1) = (q7_t) out2;
117 /* store result to destination */
118 *(pDst + 2) = (q7_t) out3;
120 /* store result to destination */
121 *(pDst + 3) = (q7_t) out4;
123 /* update pointers to process next samples */
127 /* Decrement the loop counter */
131 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
132 ** No loop unrolling is used. */
133 blkCnt = blockSize % 0x4u;
136 /* Run the below code for Cortex-M0 */
139 #endif // #define ARM_MATH_CM0_FAMILY
147 /* Store the Absolute result in the destination buffer */
148 *pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in);
150 /* Decrement the loop counter */
156 * @} end of BasicAbs group