/* go-int-array-to-string.c -- convert an array of ints to a string in Go.

   Copyright 2009 The Go Authors. All rights reserved.
   Use of this source code is governed by a BSD-style
   license that can be found in the LICENSE file.  */

#include "go-assert.h"
#include "go-string.h"
#include "runtime.h"
#include "malloc.h"

struct __go_string
__go_int_array_to_string (const void* p, size_t len)
{
  const int *ints;
  size_t slen;
  size_t i;
  unsigned char *retdata;
  struct __go_string ret;
  unsigned char *s;

  ints = (const int *) p;

  slen = 0;
  for (i = 0; i < len; ++i)
    {
      int v;

      v = ints[i];

      if (v > 0x10ffff)
	v = 0xfffd;

      if (v <= 0x7f)
	slen += 1;
      else if (v <= 0x7ff)
	slen += 2;
      else if (v <= 0xffff)
	slen += 3;
      else
	slen += 4;
    }

  retdata = runtime_mallocgc (slen, FlagNoPointers, 1, 0);
  ret.__data = retdata;
  ret.__length = slen;

  s = retdata;
  for (i = 0; i < len; ++i)
    {
      int v;

      v = ints[i];

      /* If V is out of range for UTF-8, substitute the replacement
	 character.  */
      if (v > 0x10ffff)
	v = 0xfffd;

      if (v <= 0x7f)
	*s++ = v;
      else if (v <= 0x7ff)
	{
	  *s++ = 0xc0 | ((v >> 6) & 0x1f);
	  *s++ = 0x80 | (v & 0x3f);
	}
      else if (v <= 0xffff)
	{
	  *s++ = 0xe0 | ((v >> 12) & 0xf);
	  *s++ = 0x80 | ((v >> 6) & 0x3f);
	  *s++ = 0x80 | (v & 0x3f);
	}
      else
	{
	  *s++ = 0xf0 | ((v >> 18) & 0x7);
	  *s++ = 0x80 | ((v >> 12) & 0x3f);
	  *s++ = 0x80 | ((v >> 6) & 0x3f);
	  *s++ = 0x80 | (v & 0x3f);
	}
    }

  __go_assert ((size_t) (s - retdata) == slen);

  return ret;
}