From 55389813a0f42fdf61f51a227e4dcb25c1bf5a80 Mon Sep 17 00:00:00 2001
From: Tuomo Kriikkula <tuokri@tuta.io>
Date: Fri, 24 Nov 2023 16:01:53 +0200
Subject: [PATCH] Trim trailing zeros and nuls from C++ encoded floats

---
 include/umb/coding.hpp | 10 ++++++++--
 tests/test_coding.cpp  | 18 ++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/include/umb/coding.hpp b/include/umb/coding.hpp
index 2d44050..f2858b3 100644
--- a/include/umb/coding.hpp
+++ b/include/umb/coding.hpp
@@ -31,7 +31,7 @@
 #include <string>
 #include <vector>
 
-#include <boost/lexical_cast.hpp>
+#include <boost/algorithm/string.hpp>
 
 #include "umb/constants.hpp"
 
@@ -506,7 +506,7 @@ encode_float(float f, std::string& out)
 {
     std::string str;
     // TODO: consider this precision. Does it even make sense?
-    constexpr auto pre = 64;
+    const auto pre = f > 0 ? std::numeric_limits<float>::max_digits10 : 32;
     constexpr auto longest_float = std::numeric_limits<float>::digits
                                    - std::numeric_limits<float>::min_exponent;
     constexpr auto max_str = longest_float + 8;
@@ -515,6 +515,12 @@ encode_float(float f, std::string& out)
     const auto [ptr, ec] = std::to_chars(str.data(), str.data() + str.size(), f, fmt, pre);
     if (ec == std::errc())
     {
+        str.erase(str.find('\0'));
+        // If the string has trailing zeros, trim them.
+        if ((str.size() > 1) && (str.find('0') == (str.size() - 1)))
+        {
+            boost::algorithm::trim_right_if(str, boost::algorithm::is_any_of("0"));
+        }
         out = std::move(str);
     }
     else
diff --git a/tests/test_coding.cpp b/tests/test_coding.cpp
index 336446b..5298533 100644
--- a/tests/test_coding.cpp
+++ b/tests/test_coding.cpp
@@ -327,6 +327,24 @@ TEST_CASE("encode decode float fields")
     REQUIRE(jatm1.some_floatVAR() == doctest::Approx(jatm2.some_floatVAR()));
     CHECK(Float(jatm1.some_floatVAR()).AlmostEquals(Float(jatm2.some_floatVAR())));
     CHECK_EQ(jatm1, jatm2);
+
+    jatm1.set_some_floatVAR(-8553588573958e-27);
+    vec = jatm1.to_bytes();
+    ok = jatm2.from_bytes(vec);
+    CHECK(ok);
+
+    REQUIRE(jatm1.some_floatVAR() == doctest::Approx(jatm2.some_floatVAR()));
+    CHECK(Float(jatm1.some_floatVAR()).AlmostEquals(Float(jatm2.some_floatVAR())));
+    CHECK_EQ(jatm1, jatm2);
+
+    jatm1.set_some_floatVAR(-0.0);
+    vec = jatm1.to_bytes();
+    ok = jatm2.from_bytes(vec);
+    CHECK(ok);
+
+    REQUIRE(jatm1.some_floatVAR() == doctest::Approx(jatm2.some_floatVAR()));
+    CHECK(Float(jatm1.some_floatVAR()).AlmostEquals(Float(jatm2.some_floatVAR())));
+    CHECK_EQ(jatm1, jatm2);
 }
 
 TEST_CASE("encode decode float inf/nan fields")