From f00cdc28c9fbc347ec4d35c4fcdc9d16ecc84fe9 Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Wed, 20 Jul 2022 06:11:14 +0200
Subject: [PATCH] M17 library code cleanup

---
 modemm17/Fsk4Demod.h      | 2 +-
 modemm17/LinkSetupFrame.h | 8 ++++----
 modemm17/SlidingDFT.h     | 2 +-
 modemm17/SymbolEvm.h      | 8 ++++----
 modemm17/Util.h           | 4 +---
 modemm17/Viterbi.h        | 4 ++--
 6 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/modemm17/Fsk4Demod.h b/modemm17/Fsk4Demod.h
index 38fa5df53..88d21fdef 100644
--- a/modemm17/Fsk4Demod.h
+++ b/modemm17/Fsk4Demod.h
@@ -97,7 +97,7 @@ struct Fsk4Demod
         dt = ideal_dt - (phase_estimate * (lock ? lock_gain : unlock_gain));
         t += dt;
 
-        std::tuple<int, float> evm_result = symbol_evm(samples[1]);
+        symbol_evm(samples[1]);
         int symbol;
         float evm;
         std::tie(symbol, evm) = symbol_evm(samples[1]);
diff --git a/modemm17/LinkSetupFrame.h b/modemm17/LinkSetupFrame.h
index 6efa046cf..816ce1c9e 100644
--- a/modemm17/LinkSetupFrame.h
+++ b/modemm17/LinkSetupFrame.h
@@ -135,12 +135,12 @@ struct LinkSetupFrame
         bool north = lat_int >= 0;
         bool east = lon_int >= 0;
 
-        result[2] = (int) abs(lat_int);
-        lat_dec = abs(lat_frac) * 65536.0f;
+        result[2] = (int) std::abs(lat_int);
+        lat_dec = std::abs(lat_frac) * 65536.0f;
         result[3] = lat_dec >> 8;
         result[4] = lat_dec & 0xFF;
-        result[5] = (int) abs(lon_int);
-        lon_dec = abs(lon_frac) * 65536.0f;
+        result[5] = (int) std::abs(lon_int);
+        lon_dec = std::abs(lon_frac) * 65536.0f;
         result[6] = lon_dec >> 8;
         result[7] = lon_dec & 0xFF;
         result[8] = (north ? 0 : 1) | ((east ? 0 : 1)<<1) | (1<<2);
diff --git a/modemm17/SlidingDFT.h b/modemm17/SlidingDFT.h
index f1d3abd74..d02b6839e 100644
--- a/modemm17/SlidingDFT.h
+++ b/modemm17/SlidingDFT.h
@@ -27,7 +27,7 @@ class SlidingDFT
     static constexpr float kth = float(Frequency) / float(SampleRate);
 
     // We'd like this to be static constexpr, but std::exp is not a constexpr.
-    const ComplexType coeff_;
+    ComplexType coeff_;
     std::array<float, N> samples_;
     ComplexType result_{0,0};
     size_t index_ = 0;
diff --git a/modemm17/SymbolEvm.h b/modemm17/SymbolEvm.h
index d092db2ea..4737a1d4f 100644
--- a/modemm17/SymbolEvm.h
+++ b/modemm17/SymbolEvm.h
@@ -16,7 +16,7 @@ namespace modemm17
 template <size_t N>
 struct SymbolEvm
 {
-    using filter_type = BaseIirFilter<float, N>;
+    using filter_type = BaseIirFilter<N>;
     using symbol_t = int;
     using result_type = std::tuple<symbol_t, float>;
 
@@ -42,7 +42,7 @@ struct SymbolEvm
         symbol_t symbol;
         float evm;
 
-        sample = std::min(3.0, std::max(-3.0, sample));
+        sample = std::min(3.0f, std::max(-3.0f, sample));
 
         if (sample > 2)
         {
@@ -65,7 +65,7 @@ struct SymbolEvm
             evm = (sample + 3) * 0.333333;
         }
 
-        if (erasure_limit_ and (abs(evm) > *erasure_limit_)) symbol = 0;
+        if (erasure_limit_ and (std::abs(evm) > erasure_limit_)) symbol = 0;
 
         evm_ = filter_(evm);
 
@@ -79,7 +79,7 @@ SymbolEvm<N> makeSymbolEvm(
     float erasure_limit = 0.0f
 )
 {
-    return std::move(SymbolEvm<float, N>(std::move(filter), erasure_limit));
+    return std::move(SymbolEvm<N>(std::move(filter), erasure_limit));
 }
 
 } // modemm17
diff --git a/modemm17/Util.h b/modemm17/Util.h
index cdd159464..76b755bf7 100644
--- a/modemm17/Util.h
+++ b/modemm17/Util.h
@@ -146,9 +146,7 @@ auto llr(float sample)
 template <size_t M, typename T, size_t N, typename U, size_t IN>
 auto depunctured(std::array<T, N> puncture_matrix, std::array<U, IN> in)
 {
-    if (M % N != 0) {
-        return;
-    }
+    static_assert(M % N == 0, "M must be an integer multiple of N");
 
     std::array<U, M> result;
     size_t index = 0;
diff --git a/modemm17/Viterbi.h b/modemm17/Viterbi.h
index dd269fcad..8c7b23fa4 100644
--- a/modemm17/Viterbi.h
+++ b/modemm17/Viterbi.h
@@ -94,7 +94,7 @@ constexpr auto makeCost(Trellis_ trellis)
 template <typename Trellis_, size_t LLR_ = 2>
 struct Viterbi
 {
-    static_assert(LLR_ < 7);    // Need to be < 7 to avoid overflow errors.
+    static_assert(LLR_ < 7, "Need to be < 7 to avoid overflow errors");
 
     static constexpr size_t K = Trellis_::K;
     static constexpr size_t k = Trellis_::k;
@@ -162,7 +162,7 @@ struct Viterbi
     template <size_t IN, size_t OUT>
     size_t decode(std::array<int8_t, IN> const& in, std::array<uint8_t, OUT>& out)
     {
-        static_assert(sizeof(history_) >= IN / 2);
+        static_assert(sizeof(history_) >= IN / 2, "Invalid size");
 
         constexpr auto MAX_METRIC = std::numeric_limits<typename metrics_t::value_type>::max() / 2;