leansdr::derandomizer Struct Reference

#include <dvb.h>

Inheritance diagram for leansdr::derandomizer:

Collaboration diagram for leansdr::derandomizer:

Public Member Functions
	derandomizer (scheduler *sch, pipebuf< tspacket > &_in, pipebuf< tspacket > &_out)
void	precompute_pattern ()
void	run ()
Public Member Functions inherited from leansdr::runnable
	runnable (scheduler *_sch, const char *name)
Public Member Functions inherited from leansdr::runnable_common
	runnable_common (const char *_name)
virtual	~runnable_common ()
virtual void	shutdown ()

Private Attributes
u8	pattern [188 *8]
u8 *	pattern_end
u8 *	pos
pipereader< tspacket >	in
pipewriter< tspacket >	out

Additional Inherited Members
Public Attributes inherited from leansdr::runnable_common
const char *	name
Protected Attributes inherited from leansdr::runnable
scheduler *	sch

Detailed Description

Definition at line 1371 of file dvb.h.

Constructor & Destructor Documentation

derandomizer()

leansdr::derandomizer::derandomizer ( scheduler *  sch, pipebuf< tspacket > &  _in, pipebuf< tspacket > &  _out  )

inline

Definition at line 1373 of file dvb.h.

                                          : runnable(sch, "derandomizer"),
                                            in(_in),
                                            out(_out)
    {
        precompute_pattern();
        pos = pattern;
        pattern_end = pattern + sizeof(pattern) / sizeof(pattern[0]);
    }

Member Function Documentation

precompute_pattern()

void leansdr::derandomizer::precompute_pattern ( )

inline

Definition at line 1384 of file dvb.h.

References i, and leansdr::deconvol_sync< Tbyte, BYTE_ERASED >::sync_t::out.

    {
        // EN 300 421, section 4.4.1 Transport multiplex adaptation
        pattern[0] = 0xff;          // Restore the inverted sync byte
        unsigned short st = 000251; // 0b 000 000 010 101 001 (Fig 2 reversed)

        for (int i = 1; i < 188 * 8; ++i)
        {
            u8 out = 0;

            for (int n = 8; n--;)
            {
                int bit = ((st >> 13) ^ (st >> 14)) & 1; // Taps
                out = (out << 1) | bit;                  // MSB first
                st = (st << 1) | bit;                    // Feedback
            }

            pattern[i] = (i % 188) ? out : 0; // Inhibit on sync bytes
        }
    }

run()

void leansdr::derandomizer::run ( )

inlinevirtual

Reimplemented from leansdr::runnable_common.

Definition at line 1405 of file dvb.h.

References leansdr::scheduler::debug, leansdr::deconvol_sync< Tbyte, BYTE_ERASED >::sync_t::in, leansdr::deconvol_sync< Tbyte, BYTE_ERASED >::sync_t::out, and leansdr::runnable::sch.

    {
        while (in.readable() >= 1 && out.writable() >= 1)
        {
            u8 *pin = in.rd()->data, *pend = pin + SIZE_TSPACKET;
            u8 *pout = out.wr()->data;

            if (pin[0] == MPEG_SYNC_INV || pin[0] == (MPEG_SYNC_INV ^ MPEG_SYNC_CORRUPTED))
            {
                if (pos != pattern)
                {
                    if (sch->debug)
                        fprintf(stderr, "derandomizer: resynchronizing\n");
                    pos = pattern;
                }
            }

            for (; pin < pend; ++pin, ++pout, ++pos)
            {
                *pout = *pin ^ *pos;
            }

            if (pos == pattern_end)
                pos = pattern;

            in.read(1);

            u8 sync = out.wr()->data[0];

            if (sync == MPEG_SYNC)
            {
                out.written(1);
            }
            else
            {
                if (sync != (MPEG_SYNC ^ MPEG_SYNC_CORRUPTED))
                    if (sch->debug)
                        fprintf(stderr, "(%02x)", sync);

                out.wr()->data[1] |= 0x80; // Set the Transport Error Indicator bit
                // We could output corrupted packets here, in case the
                // MPEG decoder can use them somehow.
                //out.written(1);
            }
        }
    }

Member Data Documentation

in

pipereader<tspacket> leansdr::derandomizer::in

private

Definition at line 1454 of file dvb.h.

out

pipewriter<tspacket> leansdr::derandomizer::out

private

Definition at line 1455 of file dvb.h.

pattern

u8 leansdr::derandomizer::pattern[188 *8]

private

Definition at line 1453 of file dvb.h.

pattern_end

u8 * leansdr::derandomizer::pattern_end

private

Definition at line 1453 of file dvb.h.

pos

u8 * leansdr::derandomizer::pos

private

Definition at line 1453 of file dvb.h.

---

The documentation for this struct was generated from the following file:

• plugins/channelrx/demoddatv/leansdr/dvb.h