lib: establish Zircon libc++ and KTL foundation

1 files changed, 62 insertions, 0 deletions

diff --git a/lib/ktl/include/cwchar b/lib/ktl/include/cwchar
new file mode 100644
index 0000000..4f24c73
--- /dev/null
+++ b/lib/ktl/include/cwchar
@@ -0,0 +1,62 @@
+// Copyright 2020 The Fuchsia Authors
+//
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT
+
+#ifndef ZIRCON_KERNEL_LIB_KTL_INCLUDE_CWCHAR
+#define ZIRCON_KERNEL_LIB_KTL_INCLUDE_CWCHAR
+
+// The kernel doesn't want this file but some libc++ headers we need
+// wind up including it and they need these declarations.
+
+#include <wchar.h>
+
+#include <__config>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+using ::wmemcpy;
+using ::wmemmove;
+using ::wmemset;
+
+// These are called by libc++ header code.  The first two should never actually
+// be called by anything that really gets instantiated in kernel code since
+// wchar_t is never used.  However, __constexpr_wmemchr is used by places like
+// std::find not just for wchar_t per se but for any trivial type of the same
+// size, e.g. uint32_t.  So its code must be correct.  The other two are filled
+// out just in case of an unexpected use.
+
+constexpr size_t __constexpr_wcslen(const wchar_t* str) {
+  size_t len = 0;
+  while (*str++ != L'\0') {
+    ++len;
+  }
+  return len;
+}
+
+constexpr int __constexpr_wmemcmp(const wchar_t* lhs, const wchar_t* rhs, size_t count) {
+  while (count-- > 0) {
+    if (*lhs != *rhs) {
+      return static_cast<int>(*lhs - *rhs);
+    }
+    ++lhs;
+    ++rhs;
+  }
+  return 0;
+}
+
+template <class Tp, class Up>
+constexpr Tp* __constexpr_wmemchr(Tp* str, Up wc, size_t count) {
+  while (count-- > 0) {
+    if (*str == wc) {
+      return str;
+    }
+    ++str;
+  }
+  return nullptr;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif  // ZIRCON_KERNEL_LIB_KTL_INCLUDE_CWCHAR