1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
|
/* ----------------------------------------------------------------------
* Project: CMSIS DSP Library
* Title: arm_linear_interp_q31.c
* Description: Q31 linear interpolation
*
* $Date: 23 April 2021
* $Revision: V1.9.0
*
* Target Processor: Cortex-M and Cortex-A cores
* -------------------------------------------------------------------- */
/*
* Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "dsp/interpolation_functions.h"
/**
@ingroup groupInterpolation
*/
/**
* @addtogroup BilinearInterpolate
* @{
*/
/**
* @brief Q31 bilinear interpolation.
* @param[in,out] S points to an instance of the interpolation structure.
* @param[in] X interpolation coordinate in 12.20 format.
* @param[in] Y interpolation coordinate in 12.20 format.
* @return out interpolated value.
*/
q31_t arm_bilinear_interp_q31(
arm_bilinear_interp_instance_q31 * S,
q31_t X,
q31_t Y)
{
q31_t out; /* Temporary output */
q31_t acc = 0; /* output */
q31_t xfract, yfract; /* X, Y fractional parts */
q31_t x1, x2, y1, y2; /* Nearest output values */
int32_t rI, cI; /* Row and column indices */
q31_t *pYData = S->pData; /* pointer to output table values */
uint32_t nCols = S->numCols; /* num of rows */
/* Input is in 12.20 format */
/* 12 bits for the table index */
/* Index value calculation */
rI = ((X & (q31_t)0xFFF00000) >> 20);
/* Input is in 12.20 format */
/* 12 bits for the table index */
/* Index value calculation */
cI = ((Y & (q31_t)0xFFF00000) >> 20);
/* Care taken for table outside boundary */
/* Returns zero output when values are outside table boundary */
if (rI < 0 || rI > (S->numCols - 2) || cI < 0 || cI > (S->numRows - 2))
{
return (0);
}
/* 20 bits for the fractional part */
/* shift left xfract by 11 to keep 1.31 format */
xfract = (X & 0x000FFFFF) << 11U;
/* Read two nearest output values from the index */
x1 = pYData[(rI) + (int32_t)nCols * (cI) ];
x2 = pYData[(rI) + (int32_t)nCols * (cI) + 1];
/* 20 bits for the fractional part */
/* shift left yfract by 11 to keep 1.31 format */
yfract = (Y & 0x000FFFFF) << 11U;
/* Read two nearest output values from the index */
y1 = pYData[(rI) + (int32_t)nCols * (cI + 1) ];
y2 = pYData[(rI) + (int32_t)nCols * (cI + 1) + 1];
/* Calculation of x1 * (1-xfract ) * (1-yfract) and acc is in 3.29(q29) format */
out = ((q31_t) (((q63_t) x1 * (0x7FFFFFFF - xfract)) >> 32));
acc = ((q31_t) (((q63_t) out * (0x7FFFFFFF - yfract)) >> 32));
/* x2 * (xfract) * (1-yfract) in 3.29(q29) and adding to acc */
out = ((q31_t) ((q63_t) x2 * (0x7FFFFFFF - yfract) >> 32));
acc += ((q31_t) ((q63_t) out * (xfract) >> 32));
/* y1 * (1 - xfract) * (yfract) in 3.29(q29) and adding to acc */
out = ((q31_t) ((q63_t) y1 * (0x7FFFFFFF - xfract) >> 32));
acc += ((q31_t) ((q63_t) out * (yfract) >> 32));
/* y2 * (xfract) * (yfract) in 3.29(q29) and adding to acc */
out = ((q31_t) ((q63_t) y2 * (xfract) >> 32));
acc += ((q31_t) ((q63_t) out * (yfract) >> 32));
/* Convert acc to 1.31(q31) format */
return ((q31_t)(acc << 2));
}
/**
* @} end of BilinearInterpolate group
*/
|
