/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-â
âvi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :viâ
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â Copyright 2020 Justine Alexandra Roberts Tunney                              â
â                                                                              â
â Permission to use, copy, modify, and/or distribute this software for         â
â any purpose with or without fee is hereby granted, provided that the         â
â above copyright notice and this permission notice appear in all copies.      â
â                                                                              â
â THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                â
â WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                â
â WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             â
â AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         â
â DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        â
â PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               â
â TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             â
â PERFORMANCE OF THIS SOFTWARE.                                                â
ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ*/
#include "libc/str/str.h"
#ifndef __aarch64__

// TODO(jart): ASAN support here is important.

typedef char xmm_u __attribute__((__vector_size__(16), __aligned__(1)));
typedef char xmm_t __attribute__((__vector_size__(16), __aligned__(16)));

#ifdef __x86_64__
static inline noasan size_t stpcpy_sse2(char *d, const char *s, size_t i) {
  xmm_t v, z = {0};
  for (;;) {
    v = *(xmm_t *)(s + i);
    if (!__builtin_ia32_pmovmskb128(v == z)) {
      *(xmm_u *)(d + i) = v;
      i += 16;
    } else {
      break;
    }
  }
  return i;
}
#endif

/**
 * Copies bytes from ð  to ð until a NUL is encountered.
 *
 * @param ð is destination memory
 * @param ð  is a NUL-terminated string
 * @note ð and ð  can't overlap
 * @return pointer to nul byte
 * @asyncsignalsafe
 */
char *stpcpy(char *d, const char *s) {
  size_t i = 0;
#ifdef __x86_64__
  for (; (uintptr_t)(s + i) & 15; ++i) {
    if (!(d[i] = s[i])) {
      return d + i;
    }
  }
  i = stpcpy_sse2(d, s, i);
#endif
  for (;;) {
    if (!(d[i] = s[i])) {
      return d + i;
    }
    ++i;
  }
}

#endif /* __aarch64__ */
