7 files changed, 82 insertions, 37 deletions
diff --git a/libc/src/wchar/CMakeLists.txt b/libc/src/wchar/CMakeLists.txt
index 43f44a9..49f4a1b 100644
--- a/libc/src/wchar/CMakeLists.txt
+++ b/libc/src/wchar/CMakeLists.txt
@@ -137,6 +137,21 @@ add_entrypoint_object(
 )
 
 add_entrypoint_object(
+  mbsinit
+  SRCS
+    mbsinit.cpp
+  HDRS
+    mbsinit.h
+  DEPENDS
+    libc.hdr.types.wchar_t
+    libc.hdr.types.mbstate_t
+    libc.src.__support.common
+    libc.src.__support.macros.config
+    libc.src.__support.wchar.character_converter
+    libc.src.__support.wchar.mbstate
+)
+
+add_entrypoint_object(
   mbrtowc
   SRCS
     mbrtowc.cpp
diff --git a/libc/src/wchar/mbsinit.cpp b/libc/src/wchar/mbsinit.cpp
new file mode 100644
index 0000000..23ba542
--- /dev/null
+++ b/libc/src/wchar/mbsinit.cpp
@@ -0,0 +1,26 @@
+//===-- Implementation of mbsinit -----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/wchar/mbsinit.h"
+
+#include "hdr/types/mbstate_t.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/wchar/character_converter.h"
+#include "src/__support/wchar/mbstate.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, mbsinit, (mbstate_t * ps)) {
+  if (ps == nullptr)
+    return true;
+  internal::CharacterConverter cr(reinterpret_cast<internal::mbstate *>(ps));
+  return cr.isValidState() && cr.isEmpty();
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/wchar/mbsinit.h b/libc/src/wchar/mbsinit.h
new file mode 100644
index 0000000..fa6be0f
--- /dev/null
+++ b/libc/src/wchar/mbsinit.h
@@ -0,0 +1,22 @@
+//===-- Implementation header for mbsinit ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_WCHAR_MBSINIT_H
+#define LLVM_LIBC_SRC_WCHAR_MBSINIT_H
+
+#include "hdr/types/mbstate_t.h"
+#include "hdr/types/size_t.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int mbsinit(mbstate_t *ps);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_WCHAR_MBSINIT_H
diff --git a/libc/src/wchar/wchar_utils.h b/libc/src/wchar/wchar_utils.h
index e0218c7..55a3cee 100644
--- a/libc/src/wchar/wchar_utils.h
+++ b/libc/src/wchar/wchar_utils.h
@@ -17,13 +17,10 @@
 namespace LIBC_NAMESPACE_DECL {
 namespace internal {
 
-// returns true if the character exists in the string
-LIBC_INLINE static bool wcschr(wchar_t c, const wchar_t *str) {
-  for (int n = 0; str[n]; ++n) {
-    if (str[n] == c)
-      return true;
-  }
-  return false;
+LIBC_INLINE static const wchar_t *wcschr(const wchar_t *s, wchar_t c) {
+  for (; *s && *s != c; ++s)
+    ;
+  return (*s == c) ? s : nullptr;
 }
 
 // bool should be true for wcscspn for complimentary span
@@ -32,7 +29,7 @@ LIBC_INLINE static size_t wcsspn(const wchar_t *s1, const wchar_t *s2,
                                  bool not_match_set) {
   size_t i = 0;
   for (; s1[i]; ++i) {
-    bool in_set = wcschr(s1[i], s2);
+    bool in_set = internal::wcschr(s2, s1[i]);
     if (in_set == not_match_set)
       return i;
   }
diff --git a/libc/src/wchar/wcschr.cpp b/libc/src/wchar/wcschr.cpp
index defc2ce..8ac4916 100644
--- a/libc/src/wchar/wcschr.cpp
+++ b/libc/src/wchar/wcschr.cpp
@@ -11,15 +11,14 @@
 #include "hdr/types/wchar_t.h"
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
+#include "wchar_utils.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
 LLVM_LIBC_FUNCTION(const wchar_t *, wcschr, (const wchar_t *s, wchar_t c)) {
-  for (; *s && *s != c; ++s)
-    ;
-  if (*s == c)
-    return s;
-  return nullptr;
+  LIBC_CRASH_ON_NULLPTR(s);
+  return internal::wcschr(s, c);
 }
 
 } // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/wchar/wcspbrk.cpp b/libc/src/wchar/wcspbrk.cpp
index a00ba99..f329b73 100644
--- a/libc/src/wchar/wcspbrk.cpp
+++ b/libc/src/wchar/wcspbrk.cpp
@@ -11,17 +11,10 @@
 #include "hdr/types/wchar_t.h"
 #include "src/__support/common.h"
 #include "src/__support/macros/null_check.h"
+#include "src/wchar/wchar_utils.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
-bool contains_char(const wchar_t *str, wchar_t target) {
-  for (; *str != L'\0'; str++)
-    if (*str == target)
-      return true;
-
-  return false;
-}
-
 LLVM_LIBC_FUNCTION(const wchar_t *, wcspbrk,
                    (const wchar_t *src, const wchar_t *breakset)) {
   LIBC_CRASH_ON_NULLPTR(src);
@@ -29,7 +22,7 @@ LLVM_LIBC_FUNCTION(const wchar_t *, wcspbrk,
 
   // currently O(n * m), can be further optimized to O(n + m) with a hash set
   for (int src_idx = 0; src[src_idx] != 0; src_idx++)
-    if (contains_char(breakset, src[src_idx]))
+    if (internal::wcschr(breakset, src[src_idx]))
       return src + src_idx;
 
   return nullptr;
diff --git a/libc/src/wchar/wcstok.cpp b/libc/src/wchar/wcstok.cpp
index 291efc1..ed4f0aa 100644
--- a/libc/src/wchar/wcstok.cpp
+++ b/libc/src/wchar/wcstok.cpp
@@ -10,18 +10,12 @@
 
 #include "hdr/types/wchar_t.h"
 #include "src/__support/common.h"
+#include "wchar_utils.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
-bool isADelimeter(wchar_t wc, const wchar_t *delimiters) {
-  for (const wchar_t *delim_ptr = delimiters; *delim_ptr != L'\0'; ++delim_ptr)
-    if (wc == *delim_ptr)
-      return true;
-  return false;
-}
-
 LLVM_LIBC_FUNCTION(wchar_t *, wcstok,
-                   (wchar_t *__restrict str, const wchar_t *__restrict delim,
+                   (wchar_t *__restrict str, const wchar_t *__restrict delims,
                     wchar_t **__restrict context)) {
   if (str == nullptr) {
     if (*context == nullptr)
@@ -30,14 +24,13 @@ LLVM_LIBC_FUNCTION(wchar_t *, wcstok,
     str = *context;
   }
 
-  wchar_t *tok_start, *tok_end;
-  for (tok_start = str; *tok_start != L'\0' && isADelimeter(*tok_start, delim);
-       ++tok_start)
-    ;
+  wchar_t *tok_start = str;
+  while (*tok_start != L'\0' && internal::wcschr(delims, *tok_start))
+    ++tok_start;
 
-  for (tok_end = tok_start; *tok_end != L'\0' && !isADelimeter(*tok_end, delim);
-       ++tok_end)
-    ;
+  wchar_t *tok_end = tok_start;
+  while (*tok_end != L'\0' && !internal::wcschr(delims, *tok_end))
+    ++tok_end;
 
   if (*tok_end != L'\0') {
     *tok_end = L'\0';