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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_sub_f32.c
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9 *
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10 * Description: Floating-point vector subtraction.
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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 * @defgroup BasicSub Vector Subtraction
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49 *
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50 * Element-by-element subtraction of two vectors.
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51 *
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52 * <pre>
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53 * pDst[n] = pSrcA[n] - pSrcB[n], 0 <= n < blockSize.
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54 * </pre>
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55 *
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56 * There are separate functions for floating-point, Q7, Q15, and Q31 data types.
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57 */
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58
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59 /**
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60 * @addtogroup BasicSub
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61 * @{
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62 */
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63
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64
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65 /**
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66 * @brief Floating-point vector subtraction.
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67 * @param[in] *pSrcA points to the first input vector
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68 * @param[in] *pSrcB points to the second input vector
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69 * @param[out] *pDst points to the output vector
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70 * @param[in] blockSize number of samples in each vector
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71 * @return none.
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72 */
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73
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74 void arm_sub_f32(
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75 float32_t * pSrcA,
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76 float32_t * pSrcB,
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77 float32_t * pDst,
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78 uint32_t blockSize)
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79 {
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80 uint32_t blkCnt; /* loop counter */
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81
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82 #ifndef ARM_MATH_CM0_FAMILY
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83
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84 /* Run the below code for Cortex-M4 and Cortex-M3 */
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85 float32_t inA1, inA2, inA3, inA4; /* temporary variables */
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86 float32_t inB1, inB2, inB3, inB4; /* temporary variables */
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87
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88 /*loop Unrolling */
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89 blkCnt = blockSize >> 2u;
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90
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91 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
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92 ** a second loop below computes the remaining 1 to 3 samples. */
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93 while(blkCnt > 0u)
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94 {
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95 /* C = A - B */
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96 /* Subtract and then store the results in the destination buffer. */
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97 /* Read 4 input samples from sourceA and sourceB */
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98 inA1 = *pSrcA;
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99 inB1 = *pSrcB;
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100 inA2 = *(pSrcA + 1);
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101 inB2 = *(pSrcB + 1);
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102 inA3 = *(pSrcA + 2);
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103 inB3 = *(pSrcB + 2);
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104 inA4 = *(pSrcA + 3);
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105 inB4 = *(pSrcB + 3);
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106
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107 /* dst = srcA - srcB */
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108 /* subtract and store the result */
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109 *pDst = inA1 - inB1;
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110 *(pDst + 1) = inA2 - inB2;
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111 *(pDst + 2) = inA3 - inB3;
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112 *(pDst + 3) = inA4 - inB4;
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113
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114
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115 /* Update pointers to process next sampels */
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116 pSrcA += 4u;
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117 pSrcB += 4u;
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118 pDst += 4u;
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119
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120 /* Decrement the loop counter */
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121 blkCnt--;
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122 }
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123
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124 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
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125 ** No loop unrolling is used. */
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126 blkCnt = blockSize % 0x4u;
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127
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128 #else
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129
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130 /* Run the below code for Cortex-M0 */
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131
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132 /* Initialize blkCnt with number of samples */
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133 blkCnt = blockSize;
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134
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135 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
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136
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137 while(blkCnt > 0u)
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138 {
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139 /* C = A - B */
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140 /* Subtract and then store the results in the destination buffer. */
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141 *pDst++ = (*pSrcA++) - (*pSrcB++);
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142
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143 /* Decrement the loop counter */
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144 blkCnt--;
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145 }
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146 }
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147
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148 /**
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149 * @} end of BasicSub group
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150 */
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