diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/media/test-drivers/vidtv/vidtv_ts.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/drivers/media/test-drivers/vidtv/vidtv_ts.c b/drivers/media/test-drivers/vidtv/vidtv_ts.c new file mode 100644 index 000000000..ca4bb9c40 --- /dev/null +++ b/drivers/media/test-drivers/vidtv/vidtv_ts.c @@ -0,0 +1,136 @@ +// 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; +} |