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1 /* ----------------------------------------------------------------------
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2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
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3 *
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4 * $Date: 19. March 2015
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5 * $Revision: V.1.4.5
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6 *
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7 * Project: CMSIS DSP Library
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8 * Title: arm_abs_q7.c
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9 *
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10 * Description: Q7 vector absolute value.
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11 *
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12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
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13 *
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14 * Redistribution and use in source and binary forms, with or without
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15 * modification, are permitted provided that the following conditions
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16 * are met:
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17 * - Redistributions of source code must retain the above copyright
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18 * notice, this list of conditions and the following disclaimer.
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19 * - Redistributions in binary form must reproduce the above copyright
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20 * notice, this list of conditions and the following disclaimer in
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21 * the documentation and/or other materials provided with the
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22 * distribution.
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23 * - Neither the name of ARM LIMITED nor the names of its contributors
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24 * may be used to endorse or promote products derived from this
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25 * software without specific prior written permission.
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26 *
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27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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38 * POSSIBILITY OF SUCH DAMAGE.
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39 * -------------------------------------------------------------------- */
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40
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41 #include "arm_math.h"
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42
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43 /**
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44 * @ingroup groupMath
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45 */
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46
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47 /**
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48 * @addtogroup BasicAbs
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49 * @{
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50 */
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51
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52 /**
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53 * @brief Q7 vector absolute value.
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54 * @param[in] *pSrc points to the input buffer
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55 * @param[out] *pDst points to the output buffer
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56 * @param[in] blockSize number of samples in each vector
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57 * @return none.
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58 *
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59 * \par Conditions for optimum performance
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60 * Input and output buffers should be aligned by 32-bit
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61 *
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62 *
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63 * <b>Scaling and Overflow Behavior:</b>
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64 * \par
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65 * The function uses saturating arithmetic.
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66 * The Q7 value -1 (0x80) will be saturated to the maximum allowable positive value 0x7F.
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67 */
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68
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69 void arm_abs_q7(
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70 q7_t * pSrc,
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71 q7_t * pDst,
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72 uint32_t blockSize)
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73 {
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74 uint32_t blkCnt; /* loop counter */
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75 q7_t in; /* Input value1 */
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76
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77 #ifndef ARM_MATH_CM0_FAMILY
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78
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79 /* Run the below code for Cortex-M4 and Cortex-M3 */
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80 q31_t in1, in2, in3, in4; /* temporary input variables */
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81 q31_t out1, out2, out3, out4; /* temporary output variables */
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82
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83 /*loop Unrolling */
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84 blkCnt = blockSize >> 2u;
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85
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86 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
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87 ** a second loop below computes the remaining 1 to 3 samples. */
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88 while(blkCnt > 0u)
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89 {
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90 /* C = |A| */
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91 /* Read inputs */
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92 in1 = (q31_t) * pSrc;
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93 in2 = (q31_t) * (pSrc + 1);
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94 in3 = (q31_t) * (pSrc + 2);
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95
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96 /* find absolute value */
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97 out1 = (in1 > 0) ? in1 : (q31_t)__QSUB8(0, in1);
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98
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99 /* read input */
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100 in4 = (q31_t) * (pSrc + 3);
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101
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102 /* find absolute value */
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103 out2 = (in2 > 0) ? in2 : (q31_t)__QSUB8(0, in2);
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104
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105 /* store result to destination */
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106 *pDst = (q7_t) out1;
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107
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108 /* find absolute value */
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109 out3 = (in3 > 0) ? in3 : (q31_t)__QSUB8(0, in3);
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110
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111 /* find absolute value */
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112 out4 = (in4 > 0) ? in4 : (q31_t)__QSUB8(0, in4);
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113
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114 /* store result to destination */
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115 *(pDst + 1) = (q7_t) out2;
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116
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117 /* store result to destination */
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118 *(pDst + 2) = (q7_t) out3;
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119
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120 /* store result to destination */
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121 *(pDst + 3) = (q7_t) out4;
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122
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123 /* update pointers to process next samples */
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124 pSrc += 4u;
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125 pDst += 4u;
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126
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127 /* Decrement the loop counter */
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128 blkCnt--;
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129 }
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130
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131 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
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132 ** No loop unrolling is used. */
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133 blkCnt = blockSize % 0x4u;
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134 #else
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135
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136 /* Run the below code for Cortex-M0 */
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137 blkCnt = blockSize;
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138
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139 #endif /* #define ARM_MATH_CM0_FAMILY */
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140
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141 while(blkCnt > 0u)
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142 {
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143 /* C = |A| */
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144 /* Read the input */
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145 in = *pSrc++;
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146
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147 /* Store the Absolute result in the destination buffer */
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148 *pDst++ = (in > 0) ? in : ((in == (q7_t) 0x80) ? 0x7f : -in);
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149
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150 /* Decrement the loop counter */
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151 blkCnt--;
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152 }
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153 }
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154
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155 /**
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156 * @} end of BasicAbs group
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157 */
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