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