1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * TW5864 driver - H.264 headers generation functions
4 *
5 * Copyright (C) 2016 Bluecherry, LLC <maintainers@bluecherrydvr.com>
6 */
7
8 #include <linux/log2.h>
9
10 #include "tw5864.h"
11
12 static u8 marker[] = { 0x00, 0x00, 0x00, 0x01 };
13
14 /*
15 * Exponential-Golomb coding functions
16 *
17 * These functions are used for generation of H.264 bitstream headers.
18 *
19 * This code is derived from tw5864 reference driver by manufacturers, which
20 * itself apparently was derived from x264 project.
21 */
22
23 /* Bitstream writing context */
24 struct bs {
25 u8 *buf; /* pointer to buffer beginning */
26 u8 *buf_end; /* pointer to buffer end */
27 u8 *ptr; /* pointer to current byte in buffer */
28 unsigned int bits_left; /* number of available bits in current byte */
29 };
30
bs_init(struct bs * s,void * buf,int size)31 static void bs_init(struct bs *s, void *buf, int size)
32 {
33 s->buf = buf;
34 s->ptr = buf;
35 s->buf_end = s->ptr + size;
36 s->bits_left = 8;
37 }
38
bs_len(struct bs * s)39 static int bs_len(struct bs *s)
40 {
41 return s->ptr - s->buf;
42 }
43
bs_write(struct bs * s,int count,u32 bits)44 static void bs_write(struct bs *s, int count, u32 bits)
45 {
46 if (s->ptr >= s->buf_end - 4)
47 return;
48 while (count > 0) {
49 if (count < 32)
50 bits &= (1 << count) - 1;
51 if (count < s->bits_left) {
52 *s->ptr = (*s->ptr << count) | bits;
53 s->bits_left -= count;
54 break;
55 }
56 *s->ptr = (*s->ptr << s->bits_left) |
57 (bits >> (count - s->bits_left));
58 count -= s->bits_left;
59 s->ptr++;
60 s->bits_left = 8;
61 }
62 }
63
bs_write1(struct bs * s,u32 bit)64 static void bs_write1(struct bs *s, u32 bit)
65 {
66 if (s->ptr < s->buf_end) {
67 *s->ptr <<= 1;
68 *s->ptr |= bit;
69 s->bits_left--;
70 if (s->bits_left == 0) {
71 s->ptr++;
72 s->bits_left = 8;
73 }
74 }
75 }
76
bs_write_ue(struct bs * s,u32 val)77 static void bs_write_ue(struct bs *s, u32 val)
78 {
79 if (val == 0) {
80 bs_write1(s, 1);
81 } else {
82 val++;
83 bs_write(s, 2 * fls(val) - 1, val);
84 }
85 }
86
bs_write_se(struct bs * s,int val)87 static void bs_write_se(struct bs *s, int val)
88 {
89 bs_write_ue(s, val <= 0 ? -val * 2 : val * 2 - 1);
90 }
91
bs_rbsp_trailing(struct bs * s)92 static void bs_rbsp_trailing(struct bs *s)
93 {
94 bs_write1(s, 1);
95 if (s->bits_left != 8)
96 bs_write(s, s->bits_left, 0x00);
97 }
98
99 /* H.264 headers generation functions */
100
tw5864_h264_gen_sps_rbsp(u8 * buf,size_t size,int width,int height)101 static int tw5864_h264_gen_sps_rbsp(u8 *buf, size_t size, int width, int height)
102 {
103 struct bs bs, *s;
104
105 s = &bs;
106 bs_init(s, buf, size);
107 bs_write(s, 8, 0x42); /* profile_idc, baseline */
108 bs_write(s, 1, 1); /* constraint_set0_flag */
109 bs_write(s, 1, 1); /* constraint_set1_flag */
110 bs_write(s, 1, 0); /* constraint_set2_flag */
111 bs_write(s, 5, 0); /* reserved_zero_5bits */
112 bs_write(s, 8, 0x1e); /* level_idc */
113 bs_write_ue(s, 0); /* seq_parameter_set_id */
114 bs_write_ue(s, ilog2(MAX_GOP_SIZE) - 4); /* log2_max_frame_num_minus4 */
115 bs_write_ue(s, 0); /* pic_order_cnt_type */
116 /* log2_max_pic_order_cnt_lsb_minus4 */
117 bs_write_ue(s, ilog2(MAX_GOP_SIZE) - 4);
118 bs_write_ue(s, 1); /* num_ref_frames */
119 bs_write(s, 1, 0); /* gaps_in_frame_num_value_allowed_flag */
120 bs_write_ue(s, width / 16 - 1); /* pic_width_in_mbs_minus1 */
121 bs_write_ue(s, height / 16 - 1); /* pic_height_in_map_units_minus1 */
122 bs_write(s, 1, 1); /* frame_mbs_only_flag */
123 bs_write(s, 1, 0); /* direct_8x8_inference_flag */
124 bs_write(s, 1, 0); /* frame_cropping_flag */
125 bs_write(s, 1, 0); /* vui_parameters_present_flag */
126 bs_rbsp_trailing(s);
127 return bs_len(s);
128 }
129
tw5864_h264_gen_pps_rbsp(u8 * buf,size_t size,int qp)130 static int tw5864_h264_gen_pps_rbsp(u8 *buf, size_t size, int qp)
131 {
132 struct bs bs, *s;
133
134 s = &bs;
135 bs_init(s, buf, size);
136 bs_write_ue(s, 0); /* pic_parameter_set_id */
137 bs_write_ue(s, 0); /* seq_parameter_set_id */
138 bs_write(s, 1, 0); /* entropy_coding_mode_flag */
139 bs_write(s, 1, 0); /* pic_order_present_flag */
140 bs_write_ue(s, 0); /* num_slice_groups_minus1 */
141 bs_write_ue(s, 0); /* i_num_ref_idx_l0_active_minus1 */
142 bs_write_ue(s, 0); /* i_num_ref_idx_l1_active_minus1 */
143 bs_write(s, 1, 0); /* weighted_pred_flag */
144 bs_write(s, 2, 0); /* weighted_bipred_idc */
145 bs_write_se(s, qp - 26); /* pic_init_qp_minus26 */
146 bs_write_se(s, qp - 26); /* pic_init_qs_minus26 */
147 bs_write_se(s, 0); /* chroma_qp_index_offset */
148 bs_write(s, 1, 0); /* deblocking_filter_control_present_flag */
149 bs_write(s, 1, 0); /* constrained_intra_pred_flag */
150 bs_write(s, 1, 0); /* redundant_pic_cnt_present_flag */
151 bs_rbsp_trailing(s);
152 return bs_len(s);
153 }
154
tw5864_h264_gen_slice_head(u8 * buf,size_t size,unsigned int idr_pic_id,unsigned int frame_gop_seqno,int * tail_nb_bits,u8 * tail)155 static int tw5864_h264_gen_slice_head(u8 *buf, size_t size,
156 unsigned int idr_pic_id,
157 unsigned int frame_gop_seqno,
158 int *tail_nb_bits, u8 *tail)
159 {
160 struct bs bs, *s;
161 int is_i_frame = frame_gop_seqno == 0;
162
163 s = &bs;
164 bs_init(s, buf, size);
165 bs_write_ue(s, 0); /* first_mb_in_slice */
166 bs_write_ue(s, is_i_frame ? 2 : 5); /* slice_type - I or P */
167 bs_write_ue(s, 0); /* pic_parameter_set_id */
168 bs_write(s, ilog2(MAX_GOP_SIZE), frame_gop_seqno); /* frame_num */
169 if (is_i_frame)
170 bs_write_ue(s, idr_pic_id);
171
172 /* pic_order_cnt_lsb */
173 bs_write(s, ilog2(MAX_GOP_SIZE), frame_gop_seqno);
174
175 if (is_i_frame) {
176 bs_write1(s, 0); /* no_output_of_prior_pics_flag */
177 bs_write1(s, 0); /* long_term_reference_flag */
178 } else {
179 bs_write1(s, 0); /* num_ref_idx_active_override_flag */
180 bs_write1(s, 0); /* ref_pic_list_reordering_flag_l0 */
181 bs_write1(s, 0); /* adaptive_ref_pic_marking_mode_flag */
182 }
183
184 bs_write_se(s, 0); /* slice_qp_delta */
185
186 if (s->bits_left != 8) {
187 *tail = ((s->ptr[0]) << s->bits_left);
188 *tail_nb_bits = 8 - s->bits_left;
189 } else {
190 *tail = 0;
191 *tail_nb_bits = 0;
192 }
193
194 return bs_len(s);
195 }
196
tw5864_h264_put_stream_header(u8 ** buf,size_t * space_left,int qp,int width,int height)197 void tw5864_h264_put_stream_header(u8 **buf, size_t *space_left, int qp,
198 int width, int height)
199 {
200 int nal_len;
201
202 /* SPS */
203 memcpy(*buf, marker, sizeof(marker));
204 *buf += 4;
205 *space_left -= 4;
206
207 **buf = 0x67; /* SPS NAL header */
208 *buf += 1;
209 *space_left -= 1;
210
211 nal_len = tw5864_h264_gen_sps_rbsp(*buf, *space_left, width, height);
212 *buf += nal_len;
213 *space_left -= nal_len;
214
215 /* PPS */
216 memcpy(*buf, marker, sizeof(marker));
217 *buf += 4;
218 *space_left -= 4;
219
220 **buf = 0x68; /* PPS NAL header */
221 *buf += 1;
222 *space_left -= 1;
223
224 nal_len = tw5864_h264_gen_pps_rbsp(*buf, *space_left, qp);
225 *buf += nal_len;
226 *space_left -= nal_len;
227 }
228
tw5864_h264_put_slice_header(u8 ** buf,size_t * space_left,unsigned int idr_pic_id,unsigned int frame_gop_seqno,int * tail_nb_bits,u8 * tail)229 void tw5864_h264_put_slice_header(u8 **buf, size_t *space_left,
230 unsigned int idr_pic_id,
231 unsigned int frame_gop_seqno,
232 int *tail_nb_bits, u8 *tail)
233 {
234 int nal_len;
235
236 memcpy(*buf, marker, sizeof(marker));
237 *buf += 4;
238 *space_left -= 4;
239
240 /* Frame NAL header */
241 **buf = (frame_gop_seqno == 0) ? 0x25 : 0x21;
242 *buf += 1;
243 *space_left -= 1;
244
245 nal_len = tw5864_h264_gen_slice_head(*buf, *space_left, idr_pic_id,
246 frame_gop_seqno, tail_nb_bits,
247 tail);
248 *buf += nal_len;
249 *space_left -= nal_len;
250 }
251