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// SPDX-License-Identifier: GPL-2.0
/*
* The Virtual DVB test driver serves as a reference DVB driver and helps
* validate the existing APIs in the media subsystem. It can also aid
* developers working on userspace applications.
*
* Copyright (C) 2020 Daniel W. S. Almeida
*/
#define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__
#include <linux/math64.h>
#include <linux/printk.h>
#include <linux/ratelimit.h>
#include <linux/types.h>
#include "vidtv_common.h"
#include "vidtv_ts.h"
static u32 vidtv_ts_write_pcr_bits(u8 *to, u32 to_offset, u64 pcr)
{
/* Exact same from ffmpeg. PCR is a counter driven by a 27Mhz clock */
u64 div;
u64 rem;
u8 *buf = to + to_offset;
u64 pcr_low;
u64 pcr_high;
div = div64_u64_rem(pcr, 300, &rem);
pcr_low = rem; /* pcr_low = pcr % 300 */
pcr_high = div; /* pcr_high = pcr / 300 */
*buf++ = pcr_high >> 25;
*buf++ = pcr_high >> 17;
*buf++ = pcr_high >> 9;
*buf++ = pcr_high >> 1;
*buf++ = pcr_high << 7 | pcr_low >> 8 | 0x7e;
*buf++ = pcr_low;
return 6;
}
void vidtv_ts_inc_cc(u8 *continuity_counter)
{
++*continuity_counter;
if (*continuity_counter > TS_CC_MAX_VAL)
*continuity_counter = 0;
}
u32 vidtv_ts_null_write_into(struct null_packet_write_args args)
{
u32 nbytes = 0;
struct vidtv_mpeg_ts ts_header = {};
ts_header.sync_byte = TS_SYNC_BYTE;
ts_header.bitfield = cpu_to_be16(TS_NULL_PACKET_PID);
ts_header.payload = 1;
ts_header.continuity_counter = *args.continuity_counter;
/* copy TS header */
nbytes += vidtv_memcpy(args.dest_buf,
args.dest_offset + nbytes,
args.buf_sz,
&ts_header,
sizeof(ts_header));
vidtv_ts_inc_cc(args.continuity_counter);
/* fill the rest with empty data */
nbytes += vidtv_memset(args.dest_buf,
args.dest_offset + nbytes,
args.buf_sz,
TS_FILL_BYTE,
TS_PACKET_LEN - nbytes);
/* we should have written exactly _one_ 188byte packet */
if (nbytes != TS_PACKET_LEN)
pr_warn_ratelimited("Expected exactly %d bytes, got %d\n",
TS_PACKET_LEN,
nbytes);
return nbytes;
}
u32 vidtv_ts_pcr_write_into(struct pcr_write_args args)
{
u32 nbytes = 0;
struct vidtv_mpeg_ts ts_header = {};
struct vidtv_mpeg_ts_adaption ts_adap = {};
ts_header.sync_byte = TS_SYNC_BYTE;
ts_header.bitfield = cpu_to_be16(args.pid);
ts_header.scrambling = 0;
/* cc is not incremented, but it is needed. see 13818-1 clause 2.4.3.3 */
ts_header.continuity_counter = *args.continuity_counter;
ts_header.payload = 0;
ts_header.adaptation_field = 1;
/* 13818-1 clause 2.4.3.5 */
ts_adap.length = 183;
ts_adap.PCR = 1;
/* copy TS header */
nbytes += vidtv_memcpy(args.dest_buf,
args.dest_offset + nbytes,
args.buf_sz,
&ts_header,
sizeof(ts_header));
/* write the adap after the TS header */
nbytes += vidtv_memcpy(args.dest_buf,
args.dest_offset + nbytes,
args.buf_sz,
&ts_adap,
sizeof(ts_adap));
/* write the PCR optional */
nbytes += vidtv_ts_write_pcr_bits(args.dest_buf,
args.dest_offset + nbytes,
args.pcr);
nbytes += vidtv_memset(args.dest_buf,
args.dest_offset + nbytes,
args.buf_sz,
TS_FILL_BYTE,
TS_PACKET_LEN - nbytes);
/* we should have written exactly _one_ 188byte packet */
if (nbytes != TS_PACKET_LEN)
pr_warn_ratelimited("Expected exactly %d bytes, got %d\n",
TS_PACKET_LEN,
nbytes);
return nbytes;
}
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