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 #define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__
10
11 #include <linux/printk.h>
12 #include <linux/ratelimit.h>
13 #include <linux/string.h>
14 #include <linux/types.h>
15
16 #include "vidtv_common.h"
17
18 /**
19 * vidtv_memcpy() - wrapper routine to be used by MPEG-TS
20 * generator, in order to avoid going past the
21 * output buffer.
22 * @to: Starting element to where a MPEG-TS packet will
23 * be copied.
24 * @to_offset: Starting position of the @to buffer to be filled.
25 * @to_size: Size of the @to buffer.
26 * @from: Starting element of the buffer to be copied.
27 * @len: Number of elements to be copy from @from buffer
28 * into @to+ @to_offset buffer.
29 *
30 * Note:
31 * Real digital TV demod drivers should not have memcpy
32 * wrappers. We use it here because emulating MPEG-TS
33 * generation at kernelspace requires some extra care.
34 *
35 * Return:
36 * Returns the number of bytes written
37 */
vidtv_memcpy(void * to,size_t to_offset,size_t to_size,const void * from,size_t len)38 u32 vidtv_memcpy(void *to,
39 size_t to_offset,
40 size_t to_size,
41 const void *from,
42 size_t len)
43 {
44 if (unlikely(to_offset + len > to_size)) {
45 pr_err_ratelimited("overflow detected, skipping. Try increasing the buffer size. Needed %zu, had %zu\n",
46 to_offset + len,
47 to_size);
48 return 0;
49 }
50
51 memcpy(to + to_offset, from, len);
52 return len;
53 }
54
55 /**
56 * vidtv_memset() - wrapper routine to be used by MPEG-TS
57 * generator, in order to avoid going past the
58 * output buffer.
59 * @to: Starting element to set
60 * @to_offset: Starting position of the @to buffer to be filled.
61 * @to_size: Size of the @to buffer.
62 * @c: The value to set the memory to.
63 * @len: Number of elements to be copy from @from buffer
64 * into @to+ @to_offset buffer.
65 *
66 * Note:
67 * Real digital TV demod drivers should not have memset
68 * wrappers. We use it here because emulating MPEG-TS
69 * generation at kernelspace requires some extra care.
70 *
71 * Return:
72 * Returns the number of bytes written
73 */
vidtv_memset(void * to,size_t to_offset,size_t to_size,const int c,size_t len)74 u32 vidtv_memset(void *to,
75 size_t to_offset,
76 size_t to_size,
77 const int c,
78 size_t len)
79 {
80 if (unlikely(to_offset + len > to_size)) {
81 pr_err_ratelimited("overflow detected, skipping. Try increasing the buffer size. Needed %zu, had %zu\n",
82 to_offset + len,
83 to_size);
84 return 0;
85 }
86
87 memset(to + to_offset, c, len);
88 return len;
89 }
90