1 // SPDX-License-Identifier: BSD-3-Clause/
2 //
3 // Copyright(c) 2021 Intel Corporation. All rights reserved.
4 //
5 // Author: Shriram Shastry <malladi.sastry@linux.intel.com>
6 //
7 //
8
9 #include <sof/math/log.h>
10 #include <sof/audio/format.h>
11 /**
12 * Base-10 logarithm log10(x)
13 *
14 * loge = (u) computes the base-10 logarithm of
15 * u using lookup table.
16 * input u must be scalar/real number and positive
17 *
18 * +------------------+-----------------+--------+--------+
19 * | inpfxp |log10(returntype)| inpfxp | loge |
20 * +----+-----+-------+----+----+-------+--------+--------+
21 * |WLen| FLen|Signbit|WLen|FLen|Signbit| Qformat| Qformat|
22 * +----+-----+-------+----+----+-------+--------+--------+
23 * | 32 | 0 | 0 | 32 | 28 | 0 | 32.0 | 4.28 |
24 * +------------------+-----------------+--------+--------+
25 * Arguments : uint32_t numerator [1 to 4294967295, Q32.0]
26 * Return Type : uint32_t UQ4.28 [0 to 9.6329499409]
27 */
log10_int32(uint32_t numerator)28 uint32_t log10_int32(uint32_t numerator)
29 {
30 return((uint32_t)Q_SHIFT_RND((int64_t)base2_logarithm(numerator) *
31 ONE_OVER_LOG2_10, 63, 32));
32 }
33
