1 /*
2 * Copyright 2003-2021 The Music Player Daemon Project
3 * http://www.musicpd.org
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20 #include "Pack.hxx"
21 #include "util/ByteOrder.hxx"
22
23 static void
pack_sample(uint8_t * dest,const int32_t * src0)24 pack_sample(uint8_t *dest, const int32_t *src0) noexcept
25 {
26 const auto *src = (const uint8_t *)src0;
27
28 if (IsBigEndian())
29 ++src;
30
31 *dest++ = *src++;
32 *dest++ = *src++;
33 *dest++ = *src++;
34 }
35
36 void
pcm_pack_24(uint8_t * dest,const int32_t * src,const int32_t * src_end)37 pcm_pack_24(uint8_t *dest, const int32_t *src, const int32_t *src_end) noexcept
38 {
39 /* duplicate loop to help the compiler's optimizer (constant
40 parameter to the pack_sample() inline function) */
41
42 while (src < src_end) {
43 pack_sample(dest, src++);
44 dest += 3;
45 }
46 }
47
48 /**
49 * Construct a signed 24 bit integer from three bytes into a int32_t.
50 */
51 static constexpr int32_t
ConstructS24(uint8_t low,uint8_t mid,uint8_t high)52 ConstructS24(uint8_t low, uint8_t mid, uint8_t high) noexcept
53 {
54 return int32_t(low) | (int32_t(mid) << 8) | (int32_t(high) << 16) |
55 /* extend the sign bit */
56 (high & 0x80 ? ~int32_t(0xffffff) : 0);
57 }
58
59 /**
60 * Read a packed signed little-endian 24 bit integer.
61 */
62 gcc_pure
63 static int32_t
ReadS24LE(const uint8_t * src)64 ReadS24LE(const uint8_t *src) noexcept
65 {
66 return ConstructS24(src[0], src[1], src[2]);
67 }
68
69 /**
70 * Read a packed signed big-endian 24 bit integer.
71 */
72 gcc_pure
73 static int32_t
ReadS24BE(const uint8_t * src)74 ReadS24BE(const uint8_t *src) noexcept
75 {
76 return ConstructS24(src[2], src[1], src[0]);
77 }
78
79 /**
80 * Read a packed signed native-endian 24 bit integer.
81 */
82 gcc_pure
83 static int32_t
ReadS24(const uint8_t * src)84 ReadS24(const uint8_t *src) noexcept
85 {
86 return IsBigEndian() ? ReadS24BE(src) : ReadS24LE(src);
87 }
88
89 void
pcm_unpack_24(int32_t * dest,const uint8_t * src,const uint8_t * src_end)90 pcm_unpack_24(int32_t *dest,
91 const uint8_t *src, const uint8_t *src_end) noexcept
92 {
93 while (src < src_end) {
94 *dest++ = ReadS24(src);
95 src += 3;
96 }
97 }
98
99 void
pcm_unpack_24be(int32_t * dest,const uint8_t * src,const uint8_t * src_end)100 pcm_unpack_24be(int32_t *dest,
101 const uint8_t *src, const uint8_t *src_end) noexcept
102 {
103 while (src < src_end) {
104 *dest++ = ReadS24BE(src);
105 src += 3;
106 }
107 }
108