/* Copyright (C) 2025 Aryadev Chavali

 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License Version 2 for
 * details.

 * You may distribute and modify this code under the terms of the GNU General
 * Public License Version 2, which you should have received a copy of along with
 * this program.  If not, please go to <https://www.gnu.org/licenses/>.

 * Created: 2025-04-06
 * Description:
 */

#include <string.h>
#include <tag.h>

lisp_t *tag_int(i64 i)
{
  return TAG((u64)i, INT);
}

lisp_t *tag_cons(void *ptr)
{
  return TAG((u64)ptr, CONS);
}

lisp_t *tag_sym(void *ptr)
{
  return TAG((u64)ptr, SYM);
}

lisp_t *tag_ssym(const char *data, size_t size)
{
  assert(size <= 7);
  u8 buffer[sizeof(u64)];
  memset(buffer, 0, sizeof(buffer));
  // in 8 bits we have:
  //   size - 3 bits (up to 7)
  //   tag - 5 bits
  buffer[0] = size;
  buffer[0] <<= SHIFT_SSYM;
  buffer[0] |= TAG_SSYM;
  memcpy(buffer + 1, data, size);
  u64 word = 0;
  memcpy(&word, buffer, sizeof(u64));
  return (lisp_t *)word;
}

lisp_t *tag_bool(bool b)
{
  return TAG((u64)b, BOOL);
}

lisp_t *tag_vec(void *ptr)
{
  return TAG((u64)ptr, VEC);
}

lisp_t *tag_str(void *ptr)
{
  return TAG((u64)ptr, STR);
}

lisp_t *tag_char(u32 codepoint)
{
  u64 w = codepoint;
  return TAG(w, CHAR);
}

enum Tag tag_get(lisp_t *ptr)
{
  static_assert(NUM_TAGS == 9);
  if (!ptr)
    return TAG_NIL;
  else if (IS_TAG(ptr, INT))
    return TAG_INT;
  else if (IS_TAG(ptr, CHAR))
    return TAG_CHAR;
  else if (IS_TAG(ptr, SYM))
    return TAG_SYM;
  else if (IS_TAG(ptr, SSYM))
    return TAG_SSYM;
  else if (IS_TAG(ptr, BOOL))
    return TAG_BOOL;
  else if (IS_TAG(ptr, VEC))
    return TAG_VEC;
  else if (IS_TAG(ptr, STR))
    return TAG_STR;
  else if (IS_TAG(ptr, CONS))
    return TAG_CONS;
  return 0;
}