Improved trimming (#1458)

* Add threshold UI
* WIP Better trimming
* Rewrite mostly done WIP
* WIP - trim idea
* WIP threshold trimming
* WIP with new design
* Cleanup

firmware/application/iq_trim.cpp

@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) 2023 Kyle Reed
+ *
+ * This file is part of PortaPack.
+ *
+ * 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, 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; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "iq_trim.hpp"
+
+#include <memory>
+#include "string_format.hpp"
+
+namespace fs = std::filesystem;
+
+namespace iq {
+
+/* Trimming helpers based on the sample type (complex8 or complex16). */
+template <typename T>
+uint32_t power(T value) {
+    auto real = value.real();
+    auto imag = value.imag();
+    return (real * real) + (imag * imag);
+}
+
+/* Collects capture file metadata and sample power buckets. */
+template <typename T>
+Optional<CaptureInfo> profile_capture(
+    const std::filesystem::path& path,
+    PowerBuckets& buckets,
+    uint8_t samples_per_bucket) {
+    File f;
+    auto error = f.open(path);
+    if (error)
+        return {};
+
+    CaptureInfo info{
+        .file_size = f.size(),
+        .sample_count = f.size() / sizeof(T),
+        .sample_size = sizeof(T),
+        .max_power = 0};
+
+    auto profile_samples = buckets.size * samples_per_bucket;
+    auto sample_interval = info.sample_count / profile_samples;
+    uint32_t bucket_width = std::max(1ULL, info.sample_count / buckets.size);
+    uint64_t sample_index = 0;
+    T value{};
+
+    while (true) {
+        f.seek(sample_index * info.sample_size);
+        auto result = f.read(&value, info.sample_size);
+        if (!result) return {};  // Read failed.
+
+        if (*result != info.sample_size)
+            break;  // EOF
+
+        auto mag_squared = power(value);
+
+        if (mag_squared > info.max_power)
+            info.max_power = mag_squared;
+
+        auto bucket_index = sample_index / bucket_width;
+        buckets.add(bucket_index, mag_squared);
+        sample_index += sample_interval;
+    }
+
+    return info;
+}
+
+Optional<CaptureInfo> profile_capture(
+    const fs::path& path,
+    PowerBuckets& buckets,
+    uint8_t samples_per_bucket) {
+    auto sample_size = fs::capture_file_sample_size(path);
+
+    switch (sample_size) {
+        case sizeof(complex16_t):
+            return profile_capture<complex16_t>(path, buckets, samples_per_bucket);
+
+        case sizeof(complex8_t):
+            return profile_capture<complex8_t>(path, buckets, samples_per_bucket);
+
+        default:
+            return {};
+    };
+}
+
+TrimRange compute_trim_range(
+    CaptureInfo info,
+    const PowerBuckets& buckets,
+    uint8_t cutoff_percent) {
+    bool has_start = false;
+    uint8_t start_bucket = 0;
+    uint8_t end_bucket = 0;
+
+    uint32_t power_cutoff = cutoff_percent * static_cast<uint64_t>(info.max_power) / 100;
+
+    for (size_t i = 0; i < buckets.size; ++i) {
+        auto power = buckets.p[i].power;
+
+        if (power > power_cutoff) {
+            if (has_start)
+                end_bucket = i;
+            else {
+                start_bucket = i;
+                end_bucket = i;
+                has_start = true;
+            }
+        }
+    }
+
+    // End should be the first bucket after the last with signal.
+    // This makes the math downstream simpler. NB: may be > buckets.size.
+    end_bucket++;
+
+    auto samples_per_bucket = info.sample_count / buckets.size;
+    return {
+        start_bucket * samples_per_bucket,
+        end_bucket * samples_per_bucket,
+        info.sample_size};
+}
+
+bool trim_capture_with_range(
+    const fs::path& path,
+    TrimRange range,
+    const std::function<void(uint8_t)>& on_progress) {
+    constexpr size_t buffer_size = std::filesystem::max_file_block_size;
+    uint8_t buffer[buffer_size];
+    auto temp_path = path + u"-tmp";
+
+    // end_sample is the first sample to _not_ include.
+    auto start_byte = range.start_sample * range.sample_size;
+    auto end_byte = (range.end_sample * range.sample_size);
+    auto length = end_byte - start_byte;
+
+    // 'File' is 556 bytes! Heap alloc to avoid overflowing the stack.
+    auto src = std::make_unique<File>();
+    auto dst = std::make_unique<File>();
+
+    auto error = src->open(path);
+    if (error) return false;
+
+    error = dst->create(temp_path);
+    if (error) return false;
+
+    src->seek(start_byte);
+    auto processed = 0UL;
+    auto next_report = 0UL;
+    auto report_interval = length / 20UL;
+
+    while (true) {
+        auto result = src->read(buffer, buffer_size);
+        if (result.is_error()) return false;
+
+        auto remaining = length - processed;
+        auto to_write = std::min(remaining, *result);
+
+        result = dst->write(buffer, to_write);
+        if (result.is_error()) return false;
+
+        processed += *result;
+
+        if (*result < buffer_size || processed >= length)
+            break;
+
+        if (processed >= next_report) {
+            on_progress(100 * processed / length);
+            next_report += report_interval;
+        }
+    }
+
+    // Close files before renaming/deleting.
+    src.reset();
+    dst.reset();
+
+    // Delete original and overwrite with temp file.
+    delete_file(path);
+    rename_file(temp_path, path);
+    return true;
+}
+
+}  // namespace iq