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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#include <extdef.h>

#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <cmath>

#include "logicsegment.hpp"

#include <libsigrokcxx/libsigrokcxx.hpp>

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

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(shared_ptr<Logic> logic, uint64_t samplerate,
                const uint64_t expected_num_samples) :
    Segment(samplerate, logic->unit_size()),
    last_append_sample_(0)
{
    set_capacity(expected_num_samples);

    lock_guard<recursive_mutex> lock(mutex_);
    memset(mip_map_, 0, sizeof(mip_map_));
    append_payload(logic);
}

LogicSegment::~LogicSegment()
{
    lock_guard<recursive_mutex> lock(mutex_);
    for (MipMapLevel &l : mip_map_)
        free(l.data);
}

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
}

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<Logic> logic)
{
    assert(unit_size_ == logic->unit_size());
    assert((logic->data_length() % unit_size_) == 0);

    lock_guard<recursive_mutex> lock(mutex_);

    append_data(logic->data_pointer(),
        logic->data_length() / unit_size_);

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

void LogicSegment::get_samples(uint8_t *const data,
    int64_t start_sample, int64_t end_sample) const
{
    assert(data);
    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);

    lock_guard<recursive_mutex> lock(mutex_);

    const size_t size = (end_sample - start_sample) * unit_size_;
    memcpy(data, (const uint8_t*)data_.data() + start_sample * unit_size_, size);
}

void LogicSegment::reallocate_mipmap_level(MipMapLevel &m)
{
    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;
    const uint8_t *src_ptr;
    uint8_t *dest_ptr;
    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 uint8_t *const end_src_ptr = (uint8_t*)data_.data() +
        m0.length * unit_size_ * MipMapScaleFactor;
    for (src_ptr = (uint8_t*)data_.data() +
            prev_length * unit_size_ * MipMapScaleFactor;
            src_ptr < end_src_ptr;) {
        // Accumulate transitions which have occurred in this sample
        accumulator = 0;
        diff_counter = MipMapScaleFactor;
        while (diff_counter-- > 0) {
            const uint64_t sample = unpack_sample(src_ptr);
            accumulator |= last_append_sample_ ^ sample;
            last_append_sample_ = sample;
            src_ptr += unit_size_;
        }

        pack_sample(dest_ptr, accumulator);
        dest_ptr += unit_size_;
    }

    // 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 computed
        if (m.length == prev_length)
            break;

        reallocate_mipmap_level(m);

        // Subsample the level lower level
        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_sample(uint64_t index) const
{
    assert(index < sample_count_);

    return unpack_sample((uint8_t*)data_.data() + index * unit_size_);
}

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

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

    lock_guard<recursive_mutex> lock(mutex_);

    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_sample(start) & sig_mask) != 0;
    edges.push_back(pair<int64_t, bool>(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
        // 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 & ~(~0 << MipMapScalePower)) != 0;
                    index++) {
                const bool sample =
                    (get_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_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 (1) {
                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 & ~(~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 (1) {
                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_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_sample(final_index - 1) & sig_mask) != 0;
        edges.push_back(pair<int64_t, bool>(index, final_sample));

        index = final_index;
        last_sample = final_sample;
    }

    // Add the final state
    const bool end_sample = get_sample(end) & sig_mask;
    if (last_sample != end_sample)
        edges.push_back(pair<int64_t, bool>(end, end_sample));
    edges.push_back(pair<int64_t, bool>(end + 1, end_sample));
}

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 = 1 << power;
    return (x + p - 1) / p * p;
}

} // namespace data
} // namespace pv