1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Copyright (C) 2019-2020 Pengutronix, Michael Tretter <kernel@pengutronix.de>
4  */
5 
6 #ifndef __NAL_RBSP_H__
7 #define __NAL_RBSP_H__
8 
9 #include <linux/kernel.h>
10 #include <linux/types.h>
11 
12 struct rbsp;
13 
14 struct nal_rbsp_ops {
15 	int (*rbsp_bit)(struct rbsp *rbsp, int *val);
16 	int (*rbsp_bits)(struct rbsp *rbsp, int n, unsigned int *val);
17 	int (*rbsp_uev)(struct rbsp *rbsp, unsigned int *val);
18 	int (*rbsp_sev)(struct rbsp *rbsp, int *val);
19 };
20 
21 /**
22  * struct rbsp - State object for handling a raw byte sequence payload
23  * @data: pointer to the data of the rbsp
24  * @size: maximum size of the data of the rbsp
25  * @pos: current bit position inside the rbsp
26  * @num_consecutive_zeros: number of zeros before @pos
27  * @ops: per datatype functions for interacting with the rbsp
28  * @error: an error occurred while handling the rbsp
29  *
30  * This struct is passed around the various parsing functions and tracks the
31  * current position within the raw byte sequence payload.
32  *
33  * The @ops field allows to separate the operation, i.e., reading/writing a
34  * value from/to that rbsp, from the structure of the NAL unit. This allows to
35  * have a single function for iterating the NAL unit, while @ops has function
36  * pointers for handling each type in the rbsp.
37  */
38 struct rbsp {
39 	u8 *data;
40 	size_t size;
41 	unsigned int pos;
42 	unsigned int num_consecutive_zeros;
43 	struct nal_rbsp_ops *ops;
44 	int error;
45 };
46 
47 extern struct nal_rbsp_ops write;
48 extern struct nal_rbsp_ops read;
49 
50 void rbsp_init(struct rbsp *rbsp, void *addr, size_t size,
51 	       struct nal_rbsp_ops *ops);
52 void rbsp_unsupported(struct rbsp *rbsp);
53 
54 void rbsp_bit(struct rbsp *rbsp, int *value);
55 void rbsp_bits(struct rbsp *rbsp, int n, int *value);
56 void rbsp_uev(struct rbsp *rbsp, unsigned int *value);
57 void rbsp_sev(struct rbsp *rbsp, int *value);
58 
59 void rbsp_trailing_bits(struct rbsp *rbsp);
60 
61 #endif /* __NAL_RBSP_H__ */
62