1/*
2 * vivid-vbi-gen.c - vbi generator support functions.
3 *
4 * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
5 *
6 * This program is free software; you may redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; version 2 of the License.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
11 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
12 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
13 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
14 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
15 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
16 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
17 * SOFTWARE.
18 */
19
20#include <linux/errno.h>
21#include <linux/kernel.h>
22#include <linux/ktime.h>
23#include <linux/string.h>
24#include <linux/videodev2.h>
25
26#include "vivid-vbi-gen.h"
27
28static void wss_insert(u8 *wss, u32 val, unsigned size)
29{
30	while (size--)
31		*wss++ = (val & (1 << size)) ? 0xc0 : 0x10;
32}
33
34static void vivid_vbi_gen_wss_raw(const struct v4l2_sliced_vbi_data *data,
35		u8 *buf, unsigned sampling_rate)
36{
37	const unsigned rate = 5000000;	/* WSS has a 5 MHz transmission rate */
38	u8 wss[29 + 24 + 24 + 24 + 18 + 18] = { 0 };
39	const unsigned zero = 0x07;
40	const unsigned one = 0x38;
41	unsigned bit = 0;
42	u16 wss_data;
43	int i;
44
45	wss_insert(wss + bit, 0x1f1c71c7, 29); bit += 29;
46	wss_insert(wss + bit, 0x1e3c1f, 24); bit += 24;
47
48	wss_data = (data->data[1] << 8) | data->data[0];
49	for (i = 0; i <= 13; i++, bit += 6)
50		wss_insert(wss + bit, (wss_data & (1 << i)) ? one : zero, 6);
51
52	for (i = 0, bit = 0; bit < sizeof(wss); bit++) {
53		unsigned n = ((bit + 1) * sampling_rate) / rate;
54
55		while (i < n)
56			buf[i++] = wss[bit];
57	}
58}
59
60static void vivid_vbi_gen_teletext_raw(const struct v4l2_sliced_vbi_data *data,
61		u8 *buf, unsigned sampling_rate)
62{
63	const unsigned rate = 6937500 / 10;	/* Teletext has a 6.9375 MHz transmission rate */
64	u8 teletext[45] = { 0x55, 0x55, 0x27 };
65	unsigned bit = 0;
66	int i;
67
68	memcpy(teletext + 3, data->data, sizeof(teletext) - 3);
69	/* prevents 32 bit overflow */
70	sampling_rate /= 10;
71
72	for (i = 0, bit = 0; bit < sizeof(teletext) * 8; bit++) {
73		unsigned n = ((bit + 1) * sampling_rate) / rate;
74		u8 val = (teletext[bit / 8] & (1 << (bit & 7))) ? 0xc0 : 0x10;
75
76		while (i < n)
77			buf[i++] = val;
78	}
79}
80
81static void cc_insert(u8 *cc, u8 ch)
82{
83	unsigned tot = 0;
84	unsigned i;
85
86	for (i = 0; i < 7; i++) {
87		cc[2 * i] = cc[2 * i + 1] = (ch & (1 << i)) ? 1 : 0;
88		tot += cc[2 * i];
89	}
90	cc[14] = cc[15] = !(tot & 1);
91}
92
93#define CC_PREAMBLE_BITS (14 + 4 + 2)
94
95static void vivid_vbi_gen_cc_raw(const struct v4l2_sliced_vbi_data *data,
96		u8 *buf, unsigned sampling_rate)
97{
98	const unsigned rate = 1000000;	/* CC has a 1 MHz transmission rate */
99
100	u8 cc[CC_PREAMBLE_BITS + 2 * 16] = {
101		/* Clock run-in: 7 cycles */
102		0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1,
103		/* 2 cycles of 0 */
104		0, 0, 0, 0,
105		/* Start bit of 1 (each bit is two cycles) */
106		1, 1
107	};
108	unsigned bit, i;
109
110	cc_insert(cc + CC_PREAMBLE_BITS, data->data[0]);
111	cc_insert(cc + CC_PREAMBLE_BITS + 16, data->data[1]);
112
113	for (i = 0, bit = 0; bit < sizeof(cc); bit++) {
114		unsigned n = ((bit + 1) * sampling_rate) / rate;
115
116		while (i < n)
117			buf[i++] = cc[bit] ? 0xc0 : 0x10;
118	}
119}
120
121void vivid_vbi_gen_raw(const struct vivid_vbi_gen_data *vbi,
122		const struct v4l2_vbi_format *vbi_fmt, u8 *buf)
123{
124	unsigned idx;
125
126	for (idx = 0; idx < 25; idx++) {
127		const struct v4l2_sliced_vbi_data *data = vbi->data + idx;
128		unsigned start_2nd_field;
129		unsigned line = data->line;
130		u8 *linebuf = buf;
131
132		start_2nd_field = (data->id & V4L2_SLICED_VBI_525) ? 263 : 313;
133		if (data->field)
134			line += start_2nd_field;
135		line -= vbi_fmt->start[data->field];
136
137		if (vbi_fmt->flags & V4L2_VBI_INTERLACED)
138			linebuf += (line * 2 + data->field) *
139				vbi_fmt->samples_per_line;
140		else
141			linebuf += (line + data->field * vbi_fmt->count[0]) *
142				vbi_fmt->samples_per_line;
143		if (data->id == V4L2_SLICED_CAPTION_525)
144			vivid_vbi_gen_cc_raw(data, linebuf, vbi_fmt->sampling_rate);
145		else if (data->id == V4L2_SLICED_WSS_625)
146			vivid_vbi_gen_wss_raw(data, linebuf, vbi_fmt->sampling_rate);
147		else if (data->id == V4L2_SLICED_TELETEXT_B)
148			vivid_vbi_gen_teletext_raw(data, linebuf, vbi_fmt->sampling_rate);
149	}
150}
151
152static const u8 vivid_cc_sequence1[30] = {
153	0x14, 0x20,	/* Resume Caption Loading */
154	'H',  'e',
155	'l',  'l',
156	'o',  ' ',
157	'w',  'o',
158	'r',  'l',
159	'd',  '!',
160	0x14, 0x2f,	/* End of Caption */
161};
162
163static const u8 vivid_cc_sequence2[30] = {
164	0x14, 0x20,	/* Resume Caption Loading */
165	'C',  'l',
166	'o',  's',
167	'e',  'd',
168	' ',  'c',
169	'a',  'p',
170	't',  'i',
171	'o',  'n',
172	's',  ' ',
173	't',  'e',
174	's',  't',
175	0x14, 0x2f,	/* End of Caption */
176};
177
178static u8 calc_parity(u8 val)
179{
180	unsigned i;
181	unsigned tot = 0;
182
183	for (i = 0; i < 7; i++)
184		tot += (val & (1 << i)) ? 1 : 0;
185	return val | ((tot & 1) ? 0 : 0x80);
186}
187
188static void vivid_vbi_gen_set_time_of_day(u8 *packet)
189{
190	struct tm tm;
191	u8 checksum, i;
192
193	time_to_tm(get_seconds(), 0, &tm);
194	packet[0] = calc_parity(0x07);
195	packet[1] = calc_parity(0x01);
196	packet[2] = calc_parity(0x40 | tm.tm_min);
197	packet[3] = calc_parity(0x40 | tm.tm_hour);
198	packet[4] = calc_parity(0x40 | tm.tm_mday);
199	if (tm.tm_mday == 1 && tm.tm_mon == 2 &&
200	    sys_tz.tz_minuteswest > tm.tm_min + tm.tm_hour * 60)
201		packet[4] = calc_parity(0x60 | tm.tm_mday);
202	packet[5] = calc_parity(0x40 | (1 + tm.tm_mon));
203	packet[6] = calc_parity(0x40 | (1 + tm.tm_wday));
204	packet[7] = calc_parity(0x40 | ((tm.tm_year - 90) & 0x3f));
205	packet[8] = calc_parity(0x0f);
206	for (checksum = i = 0; i <= 8; i++)
207		checksum += packet[i] & 0x7f;
208	packet[9] = calc_parity(0x100 - checksum);
209	checksum = 0;
210	packet[10] = calc_parity(0x07);
211	packet[11] = calc_parity(0x04);
212	if (sys_tz.tz_minuteswest >= 0)
213		packet[12] = calc_parity(0x40 | ((sys_tz.tz_minuteswest / 60) & 0x1f));
214	else
215		packet[12] = calc_parity(0x40 | ((24 + sys_tz.tz_minuteswest / 60) & 0x1f));
216	packet[13] = calc_parity(0);
217	packet[14] = calc_parity(0x0f);
218	for (checksum = 0, i = 10; i <= 14; i++)
219		checksum += packet[i] & 0x7f;
220	packet[15] = calc_parity(0x100 - checksum);
221}
222
223static const u8 hamming[16] = {
224	0x15, 0x02, 0x49, 0x5e, 0x64, 0x73, 0x38, 0x2f,
225	0xd0, 0xc7, 0x8c, 0x9b, 0xa1, 0xb6, 0xfd, 0xea
226};
227
228static void vivid_vbi_gen_teletext(u8 *packet, unsigned line, unsigned frame)
229{
230	unsigned offset = 2;
231	unsigned i;
232
233	packet[0] = hamming[1 + ((line & 1) << 3)];
234	packet[1] = hamming[line >> 1];
235	memset(packet + 2, 0x20, 40);
236	if (line == 0) {
237		/* subcode */
238		packet[2] = hamming[frame % 10];
239		packet[3] = hamming[frame / 10];
240		packet[4] = hamming[0];
241		packet[5] = hamming[0];
242		packet[6] = hamming[0];
243		packet[7] = hamming[0];
244		packet[8] = hamming[0];
245		packet[9] = hamming[1];
246		offset = 10;
247	}
248	packet += offset;
249	memcpy(packet, "Page: 100 Row: 10", 17);
250	packet[7] = '0' + frame / 10;
251	packet[8] = '0' + frame % 10;
252	packet[15] = '0' + line / 10;
253	packet[16] = '0' + line % 10;
254	for (i = 0; i < 42 - offset; i++)
255		packet[i] = calc_parity(packet[i]);
256}
257
258void vivid_vbi_gen_sliced(struct vivid_vbi_gen_data *vbi,
259		bool is_60hz, unsigned seqnr)
260{
261	struct v4l2_sliced_vbi_data *data0 = vbi->data;
262	struct v4l2_sliced_vbi_data *data1 = vbi->data + 1;
263	unsigned frame = seqnr % 60;
264
265	memset(vbi->data, 0, sizeof(vbi->data));
266
267	if (!is_60hz) {
268		unsigned i;
269
270		for (i = 0; i <= 11; i++) {
271			data0->id = V4L2_SLICED_TELETEXT_B;
272			data0->line = 7 + i;
273			vivid_vbi_gen_teletext(data0->data, i, frame);
274			data0++;
275		}
276		data0->id = V4L2_SLICED_WSS_625;
277		data0->line = 23;
278		/* 4x3 video aspect ratio */
279		data0->data[0] = 0x08;
280		data0++;
281		for (i = 0; i <= 11; i++) {
282			data0->id = V4L2_SLICED_TELETEXT_B;
283			data0->field = 1;
284			data0->line = 7 + i;
285			vivid_vbi_gen_teletext(data0->data, 12 + i, frame);
286			data0++;
287		}
288		return;
289	}
290
291	data0->id = V4L2_SLICED_CAPTION_525;
292	data0->line = 21;
293	data1->id = V4L2_SLICED_CAPTION_525;
294	data1->field = 1;
295	data1->line = 21;
296
297	if (frame < 15) {
298		data0->data[0] = calc_parity(vivid_cc_sequence1[2 * frame]);
299		data0->data[1] = calc_parity(vivid_cc_sequence1[2 * frame + 1]);
300	} else if (frame >= 30 && frame < 45) {
301		frame -= 30;
302		data0->data[0] = calc_parity(vivid_cc_sequence2[2 * frame]);
303		data0->data[1] = calc_parity(vivid_cc_sequence2[2 * frame + 1]);
304	} else {
305		data0->data[0] = calc_parity(0);
306		data0->data[1] = calc_parity(0);
307	}
308
309	frame = seqnr % (30 * 60);
310	switch (frame) {
311	case 0:
312		vivid_vbi_gen_set_time_of_day(vbi->time_of_day_packet);
313		/* fall through */
314	case 1 ... 7:
315		data1->data[0] = vbi->time_of_day_packet[frame * 2];
316		data1->data[1] = vbi->time_of_day_packet[frame * 2 + 1];
317		break;
318	default:
319		data1->data[0] = calc_parity(0);
320		data1->data[1] = calc_parity(0);
321		break;
322	}
323}
324