logicsegment.cpp

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/*
 * This file is part of the PulseView project.
 *
 * Copyright (C) 2012 Joel Holdsworth <joel@airwebreathe.org.uk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include "config.h" // For HAVE_UNALIGNED_LITTLE_ENDIAN_ACCESS

#include <extdef.h>

#include <cassert>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <cstdint>

#include "logic.hpp"
#include "logicsegment.hpp"

#include <libsigrokcxx/libsigrokcxx.hpp>

using std::lock_guard;
using std::recursive_mutex;
using std::max;
using std::min;
using std::shared_ptr;
using std::vector;

using sigrok::Logic;

namespace pv {
namespace data {

const int LogicSegment::MipMapScalePower = 4;
const int LogicSegment::MipMapScaleFactor = 1 << MipMapScalePower;
const float LogicSegment::LogMipMapScaleFactor = logf(MipMapScaleFactor);
const uint64_t LogicSegment::MipMapDataUnit = 64 * 1024; // bytes

LogicSegment::LogicSegment(pv::data::Logic& owner, uint32_t segment_id,
    unsigned int unit_size, uint64_t samplerate) :
    Segment(segment_id, samplerate, unit_size),
    owner_(owner),
    last_append_sample_(0),
    last_append_accumulator_(0),
    last_append_extra_(0)
{
    memset(mip_map_, 0, sizeof(mip_map_));
}

LogicSegment::~LogicSegment()
{
    lock_guard<recursive_mutex> lock(mutex_);

    for (MipMapLevel &l : mip_map_)
        free(l.data);
}

shared_ptr<const LogicSegment> LogicSegment::get_shared_ptr() const
{
    shared_ptr<const Segment> ptr = nullptr;

    try {
        ptr = shared_from_this();
    } catch (std::exception& e) {
        /* Do nothing, ptr remains a null pointer */
    }

    return ptr ? std::dynamic_pointer_cast<const LogicSegment>(ptr) : nullptr;
}

template <class T>
void LogicSegment::downsampleTmain(const T*&in, T &acc, T &prev)
{
    // Accumulate one sample at a time
    for (uint64_t i = 0; i < MipMapScaleFactor; i++) {
        T sample = *in++;
        acc |= prev ^ sample;
        prev = sample;
    }
}

template <>
void LogicSegment::downsampleTmain<uint8_t>(const uint8_t*&in, uint8_t &acc, uint8_t &prev)
{
    // Handle 8 bit samples in 32 bit steps
    uint32_t prev32 = prev | prev << 8 | prev << 16 | prev << 24;
    uint32_t acc32 = acc;
    const uint32_t *in32 = (const uint32_t*)in;
    for (uint64_t i = 0; i < MipMapScaleFactor; i += 4) {
        uint32_t sample32 = *in32++;
        acc32 |= prev32 ^ sample32;
        prev32 = sample32;
    }
    // Reduce result back to uint8_t
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
    prev = (prev32 >> 24) & 0xff; // MSB is last
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
    prev = prev32 & 0xff; // LSB is last
#else
#error Endianness unknown
#endif
    acc |= acc32 & 0xff;
    acc |= (acc32 >> 8) & 0xff;
    acc |= (acc32 >> 16) & 0xff;
    acc |= (acc32 >> 24) & 0xff;
    in = (const uint8_t*)in32;
}

template <>
void LogicSegment::downsampleTmain<uint16_t>(const uint16_t*&in, uint16_t &acc, uint16_t &prev)
{
    // Handle 16 bit samples in 32 bit steps
    uint32_t prev32 = prev | prev << 16;
    uint32_t acc32 = acc;
    const uint32_t *in32 = (const uint32_t*)in;
    for (uint64_t i = 0; i < MipMapScaleFactor; i += 2) {
        uint32_t sample32 = *in32++;
        acc32 |= prev32 ^ sample32;
        prev32 = sample32;
    }
    // Reduce result back to uint16_t
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
    prev = (prev32 >> 16) & 0xffff; // MSB is last
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
    prev = prev32 & 0xffff; // LSB is last
#else
#error Endian unknown
#endif
    acc |= acc32 & 0xffff;
    acc |= (acc32 >> 16) & 0xffff;
    in = (const uint16_t*)in32;
}

template <class T>
void LogicSegment::downsampleT(const uint8_t *in_, uint8_t *&out_, uint64_t len)
{
    const T *in = (const T*)in_;
    T *out = (T*)out_;
    T prev = last_append_sample_;
    T acc = last_append_accumulator_;

    // Try to complete the previous downsample
    if (last_append_extra_) {
        while (last_append_extra_ < MipMapScaleFactor && len > 0) {
            T sample = *in++;
            acc |= prev ^ sample;
            prev = sample;
            last_append_extra_++;
            len--;
        }
        if (!len) {
            // Not enough samples available to complete downsample
            last_append_sample_ = prev;
            last_append_accumulator_ = acc;
            return;
        }
        // We have a complete downsample
        *out++ = acc;
        acc = 0;
        last_append_extra_ = 0;
    }

    // Handle complete blocks of MipMapScaleFactor samples
    while (len >= MipMapScaleFactor) {
        downsampleTmain<T>(in, acc, prev);
        len -= MipMapScaleFactor;
        // Output downsample
        *out++ = acc;
        acc = 0;
    }

    // Process remainder, not enough for a complete sample
    while (len > 0) {
        T sample = *in++;
        acc |= prev ^ sample;
        prev = sample;
        last_append_extra_++;
        len--;
    }

    // Update context
    last_append_sample_ = prev;
    last_append_accumulator_ = acc;
    out_ = (uint8_t *)out;
}

void LogicSegment::downsampleGeneric(const uint8_t *in, uint8_t *&out, uint64_t len)
{
    // Downsample using the generic unpack_sample()
    // which can handle any width between 1 and 8 bytes
    uint64_t prev = last_append_sample_;
    uint64_t acc = last_append_accumulator_;

    // Try to complete the previous downsample
    if (last_append_extra_) {
        while (last_append_extra_ < MipMapScaleFactor && len > 0) {
            const uint64_t sample = unpack_sample(in);
            in += unit_size_;
            acc |= prev ^ sample;
            prev = sample;
            last_append_extra_++;
            len--;
        }
        if (!len) {
            // Not enough samples available to complete downsample
            last_append_sample_ = prev;
            last_append_accumulator_ = acc;
            return;
        }
        // We have a complete downsample
        pack_sample(out, acc);
        out += unit_size_;
        acc = 0;
        last_append_extra_ = 0;
    }

    // Handle complete blocks of MipMapScaleFactor samples
    while (len >= MipMapScaleFactor) {
        // Accumulate one sample at a time
        for (uint64_t i = 0; i < MipMapScaleFactor; i++) {
            const uint64_t sample = unpack_sample(in);
            in += unit_size_;
            acc |= prev ^ sample;
            prev = sample;
        }
        len -= MipMapScaleFactor;
        // Output downsample
        pack_sample(out, acc);
        out += unit_size_;
        acc = 0;
    }

    // Process remainder, not enough for a complete sample
    while (len > 0) {
        const uint64_t sample = unpack_sample(in);
        in += unit_size_;
        acc |= prev ^ sample;
        prev = sample;
        last_append_extra_++;
        len--;
    }

    // Update context
    last_append_sample_ = prev;
    last_append_accumulator_ = acc;
}

inline uint64_t LogicSegment::unpack_sample(const uint8_t *ptr) const
{
#ifdef HAVE_UNALIGNED_LITTLE_ENDIAN_ACCESS
    return *(uint64_t*)ptr;
#else
    uint64_t value = 0;
    switch (unit_size_) {
    default:
        value |= ((uint64_t)ptr[7]) << 56;
        /* FALLTHRU */
    case 7:
        value |= ((uint64_t)ptr[6]) << 48;
        /* FALLTHRU */
    case 6:
        value |= ((uint64_t)ptr[5]) << 40;
        /* FALLTHRU */
    case 5:
        value |= ((uint64_t)ptr[4]) << 32;
        /* FALLTHRU */
    case 4:
        value |= ((uint32_t)ptr[3]) << 24;
        /* FALLTHRU */
    case 3:
        value |= ((uint32_t)ptr[2]) << 16;
        /* FALLTHRU */
    case 2:
        value |= ptr[1] << 8;
        /* FALLTHRU */
    case 1:
        value |= ptr[0];
        /* FALLTHRU */
    case 0:
        break;
    }
    return value;
#endif
}

inline void LogicSegment::pack_sample(uint8_t *ptr, uint64_t value)
{
#ifdef HAVE_UNALIGNED_LITTLE_ENDIAN_ACCESS
    *(uint64_t*)ptr = value;
#else
    switch (unit_size_) {
    default:
        ptr[7] = value >> 56;
        /* FALLTHRU */
    case 7:
        ptr[6] = value >> 48;
        /* FALLTHRU */
    case 6:
        ptr[5] = value >> 40;
        /* FALLTHRU */
    case 5:
        ptr[4] = value >> 32;
        /* FALLTHRU */
    case 4:
        ptr[3] = value >> 24;
        /* FALLTHRU */
    case 3:
        ptr[2] = value >> 16;
        /* FALLTHRU */
    case 2:
        ptr[1] = value >> 8;
        /* FALLTHRU */
    case 1:
        ptr[0] = value;
        /* FALLTHRU */
    case 0:
        break;
    }
#endif
}

void LogicSegment::append_payload(shared_ptr<sigrok::Logic> logic)
{
    assert(unit_size_ == logic->unit_size());
    assert((logic->data_length() % unit_size_) == 0);

    append_payload(logic->data_pointer(), logic->data_length());
}

void LogicSegment::append_payload(void *data, uint64_t data_size)
{
    assert(unit_size_ > 0);
    assert((data_size % unit_size_) == 0);

    lock_guard<recursive_mutex> lock(mutex_);

    const uint64_t prev_sample_count = sample_count_;
    const uint64_t sample_count = data_size / unit_size_;

    append_samples(data, sample_count);

    // Generate the first mip-map from the data
    append_payload_to_mipmap();

    if (sample_count > 1)
        owner_.notify_samples_added(SharedPtrToSegment(shared_from_this()),
            prev_sample_count + 1, prev_sample_count + 1 + sample_count);
    else
        owner_.notify_samples_added(SharedPtrToSegment(shared_from_this()),
            prev_sample_count + 1, prev_sample_count + 1);
}

void LogicSegment::append_subsignal_payload(unsigned int index, void *data,
    uint64_t data_size, vector<uint8_t>& destination)
{
    if (index == 0)
        destination.resize(data_size * unit_size_, 0);

    // Set the bits for this sub-signal where needed
    // Note: the bytes in *data must either be 0 or 1, nothing else
    unsigned int index_byte_offs = index / 8;
    uint8_t* output_data = destination.data() + index_byte_offs;
    uint8_t* input_data = (uint8_t*)data;

    for (uint64_t i = 0; i < data_size; i++) {
        assert((i * unit_size_ + index_byte_offs) < destination.size());
        *output_data |= (input_data[i] << index);
        output_data += unit_size_;
    }

    if (index == owner_.num_channels() - 1) {
        // We gathered sample data of all sub-signals, let's append it
        append_payload(destination.data(), destination.size());
        destination.clear();
    }
}

void LogicSegment::get_samples(int64_t start_sample,
    int64_t end_sample, uint8_t* dest) const
{
    assert(start_sample >= 0);
    assert(start_sample <= (int64_t)sample_count_);
    assert(end_sample >= 0);
    assert(end_sample <= (int64_t)sample_count_);
    assert(start_sample <= end_sample);
    assert(dest != nullptr);

    lock_guard<recursive_mutex> lock(mutex_);

    get_raw_samples(start_sample, (end_sample - start_sample), dest);
}

void LogicSegment::get_subsampled_edges(
    vector<EdgePair> &edges,
    uint64_t start, uint64_t end,
    float min_length, int sig_index, bool first_change_only)
{
    uint64_t index = start;
    unsigned int level;
    bool last_sample;
    bool fast_forward;

    assert(start <= end);
    assert(min_length > 0);
    assert(sig_index >= 0);
    assert(sig_index < 64);

    lock_guard<recursive_mutex> lock(mutex_);

    // Make sure we only process as many samples as we have
    if (end > get_sample_count())
        end = get_sample_count();

    const uint64_t block_length = (uint64_t)max(min_length, 1.0f);
    const unsigned int min_level = max((int)floorf(logf(min_length) /
        LogMipMapScaleFactor) - 1, 0);
    const uint64_t sig_mask = 1ULL << sig_index;

    // Store the initial state
    last_sample = (get_unpacked_sample(start) & sig_mask) != 0;
    if (!first_change_only)
        edges.emplace_back(index++, last_sample);

    while (index + block_length <= end) {
        //----- Continue to search -----//
        level = min_level;

        // We cannot fast-forward if there is no mip-map data at
        // the minimum level.
        fast_forward = (mip_map_[level].data != nullptr);

        if (min_length < MipMapScaleFactor) {
            // Search individual samples up to the beginning of
            // the next first level mip map block
            const uint64_t final_index = min(end, pow2_ceil(index, MipMapScalePower));

            for (; index < final_index &&
                    (index & ~((uint64_t)(~0) << MipMapScalePower)) != 0;
                    index++) {

                const bool sample = (get_unpacked_sample(index) & sig_mask) != 0;

                // If there was a change we cannot fast forward
                if (sample != last_sample) {
                    fast_forward = false;
                    break;
                }
            }
        } else {
            // If resolution is less than a mip map block,
            // round up to the beginning of the mip-map block
            // for this level of detail
            const int min_level_scale_power = (level + 1) * MipMapScalePower;
            index = pow2_ceil(index, min_level_scale_power);
            if (index >= end)
                break;

            // We can fast forward only if there was no change
            const bool sample = (get_unpacked_sample(index) & sig_mask) != 0;
            if (last_sample != sample)
                fast_forward = false;
        }

        if (fast_forward) {

            // Fast forward: This involves zooming out to higher
            // levels of the mip map searching for changes, then
            // zooming in on them to find the point where the edge
            // begins.

            // Slide right and zoom out at the beginnings of mip-map
            // blocks until we encounter a change
            while (true) {
                const int level_scale_power = (level + 1) * MipMapScalePower;
                const uint64_t offset = index >> level_scale_power;

                // Check if we reached the last block at this
                // level, or if there was a change in this block
                if (offset >= mip_map_[level].length ||
                    (get_subsample(level, offset) & sig_mask))
                    break;

                if ((offset & ~((uint64_t)(~0) << MipMapScalePower)) == 0) {
                    // If we are now at the beginning of a
                    // higher level mip-map block ascend one
                    // level
                    if ((level + 1 >= ScaleStepCount) || (!mip_map_[level + 1].data))
                        break;

                    level++;
                } else {
                    // Slide right to the beginning of the
                    // next mip map block
                    index = pow2_ceil(index + 1, level_scale_power);
                }
            }

            // Zoom in, and slide right until we encounter a change,
            // and repeat until we reach min_level
            while (true) {
                assert(mip_map_[level].data);

                const int level_scale_power = (level + 1) * MipMapScalePower;
                const uint64_t offset = index >> level_scale_power;

                // Check if we reached the last block at this
                // level, or if there was a change in this block
                if (offset >= mip_map_[level].length ||
                        (get_subsample(level, offset) & sig_mask)) {
                    // Zoom in unless we reached the minimum
                    // zoom
                    if (level == min_level)
                        break;

                    level--;
                } else {
                    // Slide right to the beginning of the
                    // next mip map block
                    index = pow2_ceil(index + 1, level_scale_power);
                }
            }

            // If individual samples within the limit of resolution,
            // do a linear search for the next transition within the
            // block
            if (min_length < MipMapScaleFactor) {
                for (; index < end; index++) {
                    const bool sample = (get_unpacked_sample(index) & sig_mask) != 0;
                    if (sample != last_sample)
                        break;
                }
            }
        }

        //----- Store the edge -----//

        // Take the last sample of the quanization block
        const int64_t final_index = index + block_length;
        if (index + block_length > end)
            break;

        // Store the final state
        const bool final_sample = (get_unpacked_sample(final_index - 1) & sig_mask) != 0;
        edges.emplace_back(index, final_sample);

        index = final_index;
        last_sample = final_sample;

        if (first_change_only)
            break;
    }

    // Add the final state
    if (!first_change_only) {
        const bool end_sample = get_unpacked_sample(end) & sig_mask;
        if (last_sample != end_sample)
            edges.emplace_back(end, end_sample);
        edges.emplace_back(end + 1, end_sample);
    }
}

void LogicSegment::get_surrounding_edges(vector<EdgePair> &dest,
    uint64_t origin_sample, float min_length, int sig_index)
{
    if (origin_sample >= sample_count_)
        return;

    // Put the edges vector on the heap, it can become quite big until we can
    // use a get_subsampled_edges() implementation that searches backwards
    vector<EdgePair>* edges = new vector<EdgePair>;

    // Get all edges to the left of origin_sample
    get_subsampled_edges(*edges, 0, origin_sample, min_length, sig_index, false);

    // If we don't specify "first only", the first and last edge are the states
    // at samples 0 and origin_sample. If only those exist, there are no edges
    if (edges->size() == 2) {
        delete edges;
        return;
    }

    // Dismiss the entry for origin_sample so that back() gives us the
    // real last entry
    edges->pop_back();
    dest.push_back(edges->back());
    edges->clear();

    // Get first edge to the right of origin_sample
    get_subsampled_edges(*edges, origin_sample, sample_count_, min_length, sig_index, true);

    // "first only" is specified, so nothing needs to be dismissed
    if (edges->size() == 0) {
        delete edges;
        return;
    }

    dest.push_back(edges->front());

    delete edges;
}

void LogicSegment::reallocate_mipmap_level(MipMapLevel &m)
{
    lock_guard<recursive_mutex> lock(mutex_);

    const uint64_t new_data_length = ((m.length + MipMapDataUnit - 1) /
        MipMapDataUnit) * MipMapDataUnit;

    if (new_data_length > m.data_length) {
        m.data_length = new_data_length;

        // Padding is added to allow for the uint64_t write word
        m.data = realloc(m.data, new_data_length * unit_size_ +
            sizeof(uint64_t));
    }
}

void LogicSegment::append_payload_to_mipmap()
{
    MipMapLevel &m0 = mip_map_[0];
    uint64_t prev_length;
    uint8_t *dest_ptr;
    SegmentDataIterator* it;
    uint64_t accumulator;
    unsigned int diff_counter;

    // Expand the data buffer to fit the new samples
    prev_length = m0.length;
    m0.length = sample_count_ / MipMapScaleFactor;

    // Break off if there are no new samples to compute
    if (m0.length == prev_length)
        return;

    reallocate_mipmap_level(m0);

    dest_ptr = (uint8_t*)m0.data + prev_length * unit_size_;

    // Iterate through the samples to populate the first level mipmap
    const uint64_t start_sample = prev_length * MipMapScaleFactor;
    const uint64_t end_sample = m0.length * MipMapScaleFactor;
    uint64_t len_sample = end_sample - start_sample;
    it = begin_sample_iteration(start_sample);
    while (len_sample > 0) {
        // Number of samples available in this chunk
        uint64_t count = get_iterator_valid_length(it);
        // Reduce if less than asked for
        count = std::min(count, len_sample);
        uint8_t *src_ptr = get_iterator_value(it);
        // Submit these contiguous samples to downsampling in bulk
        if (unit_size_ == 1)
            downsampleT<uint8_t>(src_ptr, dest_ptr, count);
        else if (unit_size_ == 2)
            downsampleT<uint16_t>(src_ptr, dest_ptr, count);
        else if (unit_size_ == 4)
            downsampleT<uint32_t>(src_ptr, dest_ptr, count);
        else if (unit_size_ == 8)
            downsampleT<uint64_t>(src_ptr, dest_ptr, count);
        else
            downsampleGeneric(src_ptr, dest_ptr, count);
        len_sample -= count;
        // Advance iterator, should move to start of next chunk
        continue_sample_iteration(it, count);
    }
    end_sample_iteration(it);

    // Compute higher level mipmaps
    for (unsigned int level = 1; level < ScaleStepCount; level++) {
        MipMapLevel &m = mip_map_[level];
        const MipMapLevel &ml = mip_map_[level - 1];

        // Expand the data buffer to fit the new samples
        prev_length = m.length;
        m.length = ml.length / MipMapScaleFactor;

        // Break off if there are no more samples to be computed
        if (m.length == prev_length)
            break;

        reallocate_mipmap_level(m);

        // Subsample the lower level
        const uint8_t* src_ptr = (uint8_t*)ml.data +
            unit_size_ * prev_length * MipMapScaleFactor;
        const uint8_t *const end_dest_ptr =
            (uint8_t*)m.data + unit_size_ * m.length;

        for (dest_ptr = (uint8_t*)m.data +
                unit_size_ * prev_length;
                dest_ptr < end_dest_ptr;
                dest_ptr += unit_size_) {
            accumulator = 0;
            diff_counter = MipMapScaleFactor;
            while (diff_counter-- > 0) {
                accumulator |= unpack_sample(src_ptr);
                src_ptr += unit_size_;
            }

            pack_sample(dest_ptr, accumulator);
        }
    }
}

uint64_t LogicSegment::get_unpacked_sample(uint64_t index) const
{
    assert(index < sample_count_);

    assert(unit_size_ <= 8);  // 8 * 8 = 64 channels
    uint8_t data[8];

    get_raw_samples(index, 1, data);

    return unpack_sample(data);
}

uint64_t LogicSegment::get_subsample(int level, uint64_t offset) const
{
    assert(level >= 0);
    assert(mip_map_[level].data);
    return unpack_sample((uint8_t*)mip_map_[level].data +
        unit_size_ * offset);
}

uint64_t LogicSegment::pow2_ceil(uint64_t x, unsigned int power)
{
    const uint64_t p = UINT64_C(1) << power;
    return (x + p - 1) / p * p;
}

} // namespace data
} // namespace pv