From 5b32118626b8bdbcadfb5c6a715e12dfc36e069f Mon Sep 17 00:00:00 2001
From: Dan Paulat <dpaulat@gmail.com>
Date: Sat, 9 Apr 2022 21:03:49 -0500
Subject: [PATCH] Raster Data Packet RLE decoding to levels

---
 .../scwx/wsr88d/rpg/raster_data_packet.hpp    |  2 ++
 .../scwx/wsr88d/rpg/raster_data_packet.cpp    | 30 ++++++++++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/wxdata/include/scwx/wsr88d/rpg/raster_data_packet.hpp b/wxdata/include/scwx/wsr88d/rpg/raster_data_packet.hpp
index db1e0726..b24f87b0 100644
--- a/wxdata/include/scwx/wsr88d/rpg/raster_data_packet.hpp
+++ b/wxdata/include/scwx/wsr88d/rpg/raster_data_packet.hpp
@@ -37,6 +37,8 @@ public:
    uint16_t number_of_rows() const;
    uint16_t packaging_descriptor() const;
 
+   const std::vector<uint8_t>& level(uint16_t r) const;
+
    size_t data_size() const override;
 
    bool Parse(std::istream& is) override;
diff --git a/wxdata/source/scwx/wsr88d/rpg/raster_data_packet.cpp b/wxdata/source/scwx/wsr88d/rpg/raster_data_packet.cpp
index fb0bf908..3915ed7b 100644
--- a/wxdata/source/scwx/wsr88d/rpg/raster_data_packet.cpp
+++ b/wxdata/source/scwx/wsr88d/rpg/raster_data_packet.cpp
@@ -22,8 +22,9 @@ public:
    {
       uint16_t             numberOfBytes_;
       std::vector<uint8_t> data_;
+      std::vector<uint8_t> level_;
 
-      Row() : numberOfBytes_ {0}, data_ {} {}
+      Row() : numberOfBytes_ {0}, data_ {}, level_ {} {}
    };
 
    explicit RasterDataPacketImpl() :
@@ -120,6 +121,11 @@ uint16_t RasterDataPacket::packaging_descriptor() const
    return p->packagingDescriptor_;
 }
 
+const std::vector<uint8_t>& RasterDataPacket::level(uint16_t r) const
+{
+   return p->row_[r].level_;
+}
+
 size_t RasterDataPacket::data_size() const
 {
    return p->dataSize_;
@@ -212,6 +218,28 @@ bool RasterDataPacket::Parse(std::istream& is)
          {
             row.data_.pop_back();
          }
+
+         // Unpack the levels from the Run Length Encoded data
+         uint16_t binCount =
+            std::accumulate(row.data_.cbegin(),
+                            row.data_.cend(),
+                            0,
+                            [](const uint16_t& a, const uint8_t& b) -> uint16_t
+                            { return a + (b >> 4); });
+
+         row.level_.resize(binCount);
+
+         uint16_t b = 0;
+         for (auto it = row.data_.cbegin(); it != row.data_.cend(); it++)
+         {
+            uint8_t run   = *it >> 4;
+            uint8_t level = *it & 0x0f;
+
+            for (int i = 0; i < run && b < binCount; i++)
+            {
+               row.level_[b++] = level;
+            }
+         }
       }
    }