From e0e5623b46fdaa0988faa76af506d5bc1035ee42 Mon Sep 17 00:00:00 2001
From: Roland Reichwein <mail@reichwein.it>
Date: Sun, 26 Dec 2021 16:58:04 +0100
Subject: Optimization fixes

---
 include/unicode.h | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/include/unicode.h b/include/unicode.h
index 3d6477c..395f172 100644
--- a/include/unicode.h
+++ b/include/unicode.h
@@ -31,6 +31,13 @@ namespace unicode {
  template<typename T>
  static inline bool is_valid_unicode(const T& value) noexcept
  {
+  if constexpr(sizeof(T) == 1)
+   return true;
+  else if constexpr(sizeof(T) == 2)
+   //return value <= 0xD7FF || value >= 0xE000;
+   return (value & 0xF800) != 0xD800;
+  else
+   //return (value & 0xFFFFF800) != 0x0000D800 && (value >> 16) <= 0x10;
    return value <= 0xD7FF || (value >= 0xE000 && value <= 0x10FFFF);
  }
 
@@ -161,7 +168,7 @@ namespace unicode::detail {
   {
    char16_t unit0 {static_cast<char16_t>(get_code_unit<0>())};
 
-   if (unit0 <= 0xD7FF || unit0 >= 0xE000) { // 1 unit (BMP Basic Multilingual Plane)
+   if (is_valid_unicode(unit0)) { // 1 unit (BMP Basic Multilingual Plane)
     std::advance(iterator, 1);
     return unit0;
    } else {
@@ -547,10 +554,16 @@ namespace unicode {
 
  // std::distance doesn't work here: it is based on "output" distance of iterators
  template<class Iterator>
- size_t input_distance(const Iterator& it1, const Iterator& it2)
+ inline size_t input_distance(const Iterator& it1, const Iterator& it2)
  {
   return it2 - it1;
  }
+ 
+ template<class Iterator>
+ inline size_t input_distance_bytes(const Iterator& it1, const Iterator& it2)
+ {
+  return input_distance(it1, it2) * sizeof(typename Iterator::value_type);
+ }
 
  // Optimizations following:
  static const size_t accu_size {sizeof(size_t)};
@@ -637,7 +650,8 @@ namespace unicode {
               static_cast<typename output_string_type::value_type>(addr[1])});
    }
   }
- };
+
+ }; // class ArchitectureOptimizer
 
  // From and To are facets
  template<typename From, typename To, std::enable_if_t<std::is_empty<From>::value, bool> = true>
@@ -653,16 +667,17 @@ namespace unicode {
    auto end{From::end(s)};
    auto back_inserter{To::back_inserter(result)};
    auto addr{reinterpret_cast<const typename arch_optimizer::accu_type*>(&s.data()[s.size() - input_distance(begin, end)])};
-   while (input_distance(begin, end) >= accu_size) {
+   while (input_distance_bytes(begin, end) >= accu_size) {
     if (((uintptr_t)(void*)addr & arch_optimizer::addr_mask) == 0) {
-     while (input_distance(begin, end) >= accu_size) {
+     while (input_distance_bytes(begin, end) >= accu_size) {
       typename arch_optimizer::accu_type data{*addr};
       if ((data & arch_optimizer::ascii_mask) == arch_optimizer::ascii_value) {
-       arch_optimizer::template append<typename From::value_type, typename To::string_type>(reinterpret_cast<const typename From::value_type*>(addr), result);
+       arch_optimizer::template append(reinterpret_cast<const typename From::value_type*>(addr), result);
        begin += accu_size / sizeof(typename From::value_type);
        ++addr;
       } else {
-       // just advance one code unit for now
+       // just advance one code unit for now and break to trigger unoptimized
+       // version until next accu boundary
        back_inserter = *begin;
        ++begin;
        break;
-- 
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