From fc4547b412e28164af1bf8981234c6af959ccc0b Mon Sep 17 00:00:00 2001
From: Joel Klinghed <the_jk@spawned.biz>
Date: Tue, 13 Jun 2023 10:07:16 +0200
Subject: WIP

---
 utf/src/utf32.cc | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 utf/src/utf32.cc

(limited to 'utf/src/utf32.cc')

diff --git a/utf/src/utf32.cc b/utf/src/utf32.cc
new file mode 100644
index 0000000..cfa29b6
--- /dev/null
+++ b/utf/src/utf32.cc
@@ -0,0 +1,43 @@
+#include "utf32.hh"
+
+#include "utf_error.hh"
+
+namespace utf {
+
+namespace {
+
+inline bool valid_codepoint(uint32_t c) {
+  return (c < 0xd800) || (c > 0xdfff && c <= 0x10ffff);
+}
+
+}  // namespace
+
+uint32_t read32be(std::string_view data, std::size_t& offset) {
+  if (offset > data.size() || data.size() - offset < 4)
+    return NEED_MORE;
+  uint32_t c = static_cast<uint32_t>(data[offset]) << 24
+               | static_cast<uint32_t>(data[offset + 1] & 0xff) << 16
+               | static_cast<uint32_t>(data[offset + 2] & 0xff) << 8
+               | static_cast<uint32_t>(data[offset + 3] & 0xff);
+  if (valid_codepoint(c)) {
+    offset += 4;
+    return c;
+  }
+  return INVALID;
+}
+
+uint32_t read32le(std::string_view data, std::size_t& offset) {
+  if (offset > data.size() || data.size() - offset < 4)
+    return NEED_MORE;
+  uint32_t c = static_cast<uint32_t>(data[offset + 3]) << 24
+               | static_cast<uint32_t>(data[offset + 2] & 0xff) << 16
+               | static_cast<uint32_t>(data[offset + 1] & 0xff) << 8
+               | static_cast<uint32_t>(data[offset] & 0xff);
+  if (valid_codepoint(c)) {
+    offset += 4;
+    return c;
+  }
+  return INVALID;
+}
+
+}  // namespace utf
-- 
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