#ifndef COSMOPOLITAN_LIBC_STR_UTF16_H_
#define COSMOPOLITAN_LIBC_STR_UTF16_H_
#include "libc/intrin/likely.h"

#define UTF16_MASK 0xfc00
#define UTF16_MOAR 0xd800 /* 0xD800..0xDBFF */
#define UTF16_CONT 0xdc00 /* 0xDC00..0xDFFF */

COSMOPOLITAN_C_START_

#define IsSurrogate(wc)     ((0xf800 & (wc)) == 0xd800)
#define IsHighSurrogate(wc) ((UTF16_MASK & (wc)) == UTF16_MOAR)
#define IsLowSurrogate(wc)  ((UTF16_MASK & (wc)) == UTF16_CONT)
#define IsUcs2(wc)          (((65535 & (wc)) >> 11) != 27)
#define IsUtf16Cont(wc)     IsLowSurrogate(wc) /* TODO: DELETE */
#define MergeUtf16(hi, lo)  ((((hi) - 0xD800) << 10) + ((lo) - 0xDC00) + 0x10000)
#define EncodeUtf16(wc)                                         \
  (LIKELY((0x0000 <= (wc) && (wc) <= 0xFFFF) ||                 \
          (0xE000 <= (wc) && (wc) <= 0xFFFF))                   \
       ? (wc)                                                   \
   : 0x10000 <= (wc) && (wc) <= 0x10FFFF                        \
       ? (((((wc) - 0x10000) >> 10) + 0xD800) |                 \
          (unsigned)((((wc) - 0x10000) & 1023) + 0xDC00) << 16) \
       : 0xFFFD)

COSMOPOLITAN_C_END_
#endif /* COSMOPOLITAN_LIBC_STR_UTF16_H_ */
