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1// SPDX-License-Identifier: GPL-2.02/*3 * The Virtual DVB test driver serves as a reference DVB driver and helps4 * validate the existing APIs in the media subsystem. It can also aid5 * developers working on userspace applications.6 *7 * Copyright (C) 2020 Daniel W. S. Almeida8 */9 10#define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__11 12#include <linux/math64.h>13#include <linux/printk.h>14#include <linux/ratelimit.h>15#include <linux/types.h>16 17#include "vidtv_common.h"18#include "vidtv_ts.h"19 20static u32 vidtv_ts_write_pcr_bits(u8 *to, u32 to_offset, u64 pcr)21{22 /* Exact same from ffmpeg. PCR is a counter driven by a 27Mhz clock */23 u64 div;24 u64 rem;25 u8 *buf = to + to_offset;26 u64 pcr_low;27 u64 pcr_high;28 29 div = div64_u64_rem(pcr, 300, &rem);30 31 pcr_low = rem; /* pcr_low = pcr % 300 */32 pcr_high = div; /* pcr_high = pcr / 300 */33 34 *buf++ = pcr_high >> 25;35 *buf++ = pcr_high >> 17;36 *buf++ = pcr_high >> 9;37 *buf++ = pcr_high >> 1;38 *buf++ = pcr_high << 7 | pcr_low >> 8 | 0x7e;39 *buf++ = pcr_low;40 41 return 6;42}43 44void vidtv_ts_inc_cc(u8 *continuity_counter)45{46 ++*continuity_counter;47 if (*continuity_counter > TS_CC_MAX_VAL)48 *continuity_counter = 0;49}50 51u32 vidtv_ts_null_write_into(struct null_packet_write_args args)52{53 u32 nbytes = 0;54 struct vidtv_mpeg_ts ts_header = {};55 56 ts_header.sync_byte = TS_SYNC_BYTE;57 ts_header.bitfield = cpu_to_be16(TS_NULL_PACKET_PID);58 ts_header.payload = 1;59 ts_header.continuity_counter = *args.continuity_counter;60 61 /* copy TS header */62 nbytes += vidtv_memcpy(args.dest_buf,63 args.dest_offset + nbytes,64 args.buf_sz,65 &ts_header,66 sizeof(ts_header));67 68 vidtv_ts_inc_cc(args.continuity_counter);69 70 /* fill the rest with empty data */71 nbytes += vidtv_memset(args.dest_buf,72 args.dest_offset + nbytes,73 args.buf_sz,74 TS_FILL_BYTE,75 TS_PACKET_LEN - nbytes);76 77 /* we should have written exactly _one_ 188byte packet */78 if (nbytes != TS_PACKET_LEN)79 pr_warn_ratelimited("Expected exactly %d bytes, got %d\n",80 TS_PACKET_LEN,81 nbytes);82 83 return nbytes;84}85 86u32 vidtv_ts_pcr_write_into(struct pcr_write_args args)87{88 u32 nbytes = 0;89 struct vidtv_mpeg_ts ts_header = {};90 struct vidtv_mpeg_ts_adaption ts_adap = {};91 92 ts_header.sync_byte = TS_SYNC_BYTE;93 ts_header.bitfield = cpu_to_be16(args.pid);94 ts_header.scrambling = 0;95 /* cc is not incremented, but it is needed. see 13818-1 clause 2.4.3.3 */96 ts_header.continuity_counter = *args.continuity_counter;97 ts_header.payload = 0;98 ts_header.adaptation_field = 1;99 100 /* 13818-1 clause 2.4.3.5 */101 ts_adap.length = 183;102 ts_adap.PCR = 1;103 104 /* copy TS header */105 nbytes += vidtv_memcpy(args.dest_buf,106 args.dest_offset + nbytes,107 args.buf_sz,108 &ts_header,109 sizeof(ts_header));110 111 /* write the adap after the TS header */112 nbytes += vidtv_memcpy(args.dest_buf,113 args.dest_offset + nbytes,114 args.buf_sz,115 &ts_adap,116 sizeof(ts_adap));117 118 /* write the PCR optional */119 nbytes += vidtv_ts_write_pcr_bits(args.dest_buf,120 args.dest_offset + nbytes,121 args.pcr);122 123 nbytes += vidtv_memset(args.dest_buf,124 args.dest_offset + nbytes,125 args.buf_sz,126 TS_FILL_BYTE,127 TS_PACKET_LEN - nbytes);128 129 /* we should have written exactly _one_ 188byte packet */130 if (nbytes != TS_PACKET_LEN)131 pr_warn_ratelimited("Expected exactly %d bytes, got %d\n",132 TS_PACKET_LEN,133 nbytes);134 135 return nbytes;136}137