1 /* ----------------------------------------------------------------------
2 * Project: CMSIS DSP Library
3 * Title: arm_cos_q15.c
4 * Description: Fast cosine calculation for Q15 values
5 *
6 * $Date: 23 April 2021
7 * $Revision: V1.9.0
8 *
9 * Target Processor: Cortex-M and Cortex-A cores
10 * -------------------------------------------------------------------- */
11 /*
12 * Copyright (C) 2010-2021 ARM Limited or its affiliates. All rights reserved.
13 *
14 * SPDX-License-Identifier: Apache-2.0
15 *
16 * Licensed under the Apache License, Version 2.0 (the License); you may
17 * not use this file except in compliance with the License.
18 * You may obtain a copy of the License at
19 *
20 * www.apache.org/licenses/LICENSE-2.0
21 *
22 * Unless required by applicable law or agreed to in writing, software
23 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
24 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
25 * See the License for the specific language governing permissions and
26 * limitations under the License.
27 */
28
29 #include "dsp/fast_math_functions.h"
30 #include "arm_common_tables.h"
31
32 #include <stdlib.h>
33
34 /**
35 @ingroup groupFastMath
36 */
37
38 /**
39 @defgroup divide Fixed point division
40
41 */
42
43 /**
44 @addtogroup divide
45 @{
46 */
47
48 /**
49 @brief Fixed point division
50 @param[in] numerator Numerator
51 @param[in] denominator Denominator
52 @param[out] quotient Quotient value normalized between -1.0 and 1.0
53 @param[out] shift Shift left value to get the unnormalized quotient
54 @return error status
55
56 When dividing by 0, an error ARM_MATH_NANINF is returned. And the quotient is forced
57 to the saturated negative or positive value.
58 */
59
arm_divide_q15(q15_t numerator,q15_t denominator,q15_t * quotient,int16_t * shift)60 arm_status arm_divide_q15(q15_t numerator,
61 q15_t denominator,
62 q15_t *quotient,
63 int16_t *shift)
64 {
65 int16_t sign=0;
66 q31_t temp;
67 int16_t shiftForNormalizing;
68
69 *shift = 0;
70
71 sign = (numerator>>15) ^ (denominator>>15);
72
73 if (denominator == 0)
74 {
75 if (sign)
76 {
77 *quotient = 0x8000;
78 }
79 else
80 {
81 *quotient = 0x7FFF;
82 }
83 return(ARM_MATH_NANINF);
84 }
85
86 numerator = abs(numerator);
87 denominator = abs(denominator);
88
89 temp = ((q31_t)numerator << 15) / ((q31_t)denominator);
90
91 shiftForNormalizing= 17 - __CLZ(temp);
92 if (shiftForNormalizing > 0)
93 {
94 *shift = shiftForNormalizing;
95 temp = temp >> shiftForNormalizing;
96 }
97
98 if (sign)
99 {
100 temp = -temp;
101 }
102
103 *quotient=temp;
104
105 return(ARM_MATH_SUCCESS);
106 }
107
108 /**
109 @} end of divide group
110 */
111
