1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * The Virtual DVB test driver serves as a reference DVB driver and helps |
4 | * validate the existing APIs in the media subsystem. It can also aid |
5 | * developers working on userspace applications. |
6 | * |
7 | * Copyright (C) 2020 Daniel W. S. Almeida |
8 | */ |
9 | |
10 | #define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__ |
11 | |
12 | #include <linux/math64.h> |
13 | #include <linux/printk.h> |
14 | #include <linux/ratelimit.h> |
15 | #include <linux/types.h> |
16 | |
17 | #include "vidtv_common.h" |
18 | #include "vidtv_ts.h" |
19 | |
20 | static u32 vidtv_ts_write_pcr_bits(u8 *to, u32 to_offset, u64 pcr) |
21 | { |
22 | /* Exact same from ffmpeg. PCR is a counter driven by a 27Mhz clock */ |
23 | u64 div; |
24 | u64 rem; |
25 | u8 *buf = to + to_offset; |
26 | u64 pcr_low; |
27 | u64 pcr_high; |
28 | |
29 | div = div64_u64_rem(dividend: pcr, divisor: 300, remainder: &rem); |
30 | |
31 | pcr_low = rem; /* pcr_low = pcr % 300 */ |
32 | pcr_high = div; /* pcr_high = pcr / 300 */ |
33 | |
34 | *buf++ = pcr_high >> 25; |
35 | *buf++ = pcr_high >> 17; |
36 | *buf++ = pcr_high >> 9; |
37 | *buf++ = pcr_high >> 1; |
38 | *buf++ = pcr_high << 7 | pcr_low >> 8 | 0x7e; |
39 | *buf++ = pcr_low; |
40 | |
41 | return 6; |
42 | } |
43 | |
44 | void vidtv_ts_inc_cc(u8 *continuity_counter) |
45 | { |
46 | ++*continuity_counter; |
47 | if (*continuity_counter > TS_CC_MAX_VAL) |
48 | *continuity_counter = 0; |
49 | } |
50 | |
51 | u32 vidtv_ts_null_write_into(struct null_packet_write_args args) |
52 | { |
53 | u32 nbytes = 0; |
54 | struct vidtv_mpeg_ts = {}; |
55 | |
56 | ts_header.sync_byte = TS_SYNC_BYTE; |
57 | ts_header.bitfield = cpu_to_be16(TS_NULL_PACKET_PID); |
58 | ts_header.payload = 1; |
59 | ts_header.continuity_counter = *args.continuity_counter; |
60 | |
61 | /* copy TS header */ |
62 | nbytes += vidtv_memcpy(to: args.dest_buf, |
63 | to_offset: args.dest_offset + nbytes, |
64 | to_size: args.buf_sz, |
65 | from: &ts_header, |
66 | len: sizeof(ts_header)); |
67 | |
68 | vidtv_ts_inc_cc(continuity_counter: args.continuity_counter); |
69 | |
70 | /* fill the rest with empty data */ |
71 | nbytes += vidtv_memset(to: args.dest_buf, |
72 | to_offset: args.dest_offset + nbytes, |
73 | to_size: args.buf_sz, |
74 | TS_FILL_BYTE, |
75 | TS_PACKET_LEN - nbytes); |
76 | |
77 | /* we should have written exactly _one_ 188byte packet */ |
78 | if (nbytes != TS_PACKET_LEN) |
79 | pr_warn_ratelimited("Expected exactly %d bytes, got %d\n" , |
80 | TS_PACKET_LEN, |
81 | nbytes); |
82 | |
83 | return nbytes; |
84 | } |
85 | |
86 | u32 vidtv_ts_pcr_write_into(struct pcr_write_args args) |
87 | { |
88 | u32 nbytes = 0; |
89 | struct vidtv_mpeg_ts = {}; |
90 | struct vidtv_mpeg_ts_adaption ts_adap = {}; |
91 | |
92 | ts_header.sync_byte = TS_SYNC_BYTE; |
93 | ts_header.bitfield = cpu_to_be16(args.pid); |
94 | ts_header.scrambling = 0; |
95 | /* cc is not incremented, but it is needed. see 13818-1 clause 2.4.3.3 */ |
96 | ts_header.continuity_counter = *args.continuity_counter; |
97 | ts_header.payload = 0; |
98 | ts_header.adaptation_field = 1; |
99 | |
100 | /* 13818-1 clause 2.4.3.5 */ |
101 | ts_adap.length = 183; |
102 | ts_adap.PCR = 1; |
103 | |
104 | /* copy TS header */ |
105 | nbytes += vidtv_memcpy(to: args.dest_buf, |
106 | to_offset: args.dest_offset + nbytes, |
107 | to_size: args.buf_sz, |
108 | from: &ts_header, |
109 | len: sizeof(ts_header)); |
110 | |
111 | /* write the adap after the TS header */ |
112 | nbytes += vidtv_memcpy(to: args.dest_buf, |
113 | to_offset: args.dest_offset + nbytes, |
114 | to_size: args.buf_sz, |
115 | from: &ts_adap, |
116 | len: sizeof(ts_adap)); |
117 | |
118 | /* write the PCR optional */ |
119 | nbytes += vidtv_ts_write_pcr_bits(to: args.dest_buf, |
120 | to_offset: args.dest_offset + nbytes, |
121 | pcr: args.pcr); |
122 | |
123 | nbytes += vidtv_memset(to: args.dest_buf, |
124 | to_offset: args.dest_offset + nbytes, |
125 | to_size: args.buf_sz, |
126 | TS_FILL_BYTE, |
127 | TS_PACKET_LEN - nbytes); |
128 | |
129 | /* we should have written exactly _one_ 188byte packet */ |
130 | if (nbytes != TS_PACKET_LEN) |
131 | pr_warn_ratelimited("Expected exactly %d bytes, got %d\n" , |
132 | TS_PACKET_LEN, |
133 | nbytes); |
134 | |
135 | return nbytes; |
136 | } |
137 | |