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/* 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:
*/
#ifndef TAG_H
#define TAG_H
#include "./base.h"
#include <stdbool.h>
#include <stdlib.h>
// Opaque structure to make tagged pointers a separate type from general
// pointers
typedef struct Obj lisp_t;
enum Tag
{
TAG_NIL = 0b00000000, // Atomic types
TAG_INT = 0b00000001, // special so we can encode 63 bit integers
TAG_SYM = 0b00000100,
TAG_SSYM = 0b00001000,
TAG_CHAR = 0b00001100,
TAG_BOOL = 0b00010000,
// TAG_FLOAT = 0b00010100,
TAG_CONS = 0b00000010, // Container types
TAG_VEC = 0b00000110,
TAG_STR = 0b00001010,
NUM_TAGS = 9,
};
enum Shift
{
SHIFT_INT = 1,
SHIFT_SSYM = 5,
SHIFT_CHAR = 8,
SHIFT_SYM = 8,
SHIFT_BOOL = 8,
SHIFT_FLOAT = 8,
SHIFT_CONS = 8,
SHIFT_VEC = 8,
SHIFT_STR = 8,
};
enum Mask
{
MASK_INT = 0b00000001,
MASK_SSYM = 0b00011111,
MASK_SYM = 0b11111111,
MASK_CHAR = 0b11111111,
MASK_BOOL = 0b11111111,
MASK_FLOAT = 0b11111111,
MASK_CONS = 0b11111111,
MASK_VEC = 0b11111111,
MASK_STR = 0b11111111,
};
#define TAG(PTR, TYPE) ((lisp_t *)(((PTR) << SHIFT_##TYPE) | TAG_##TYPE))
#define IS_TAG(PTR, TYPE) (((u64)(PTR) & MASK_##TYPE) == TAG_##TYPE)
#define UNTAG(PTR, TYPE) (((u64)PTR) >> SHIFT_##TYPE)
enum Tag tag_get(lisp_t *ptr);
lisp_t *tag_int(i64 i);
lisp_t *tag_char(u32 codepoint);
lisp_t *tag_sym(void *ptr);
lisp_t *tag_ssym(const char *data, size_t size);
lisp_t *tag_bool(bool b);
lisp_t *tag_vec(void *ptr);
lisp_t *tag_str(void *ptr);
lisp_t *tag_cons(void *ptr);
#define INT_MAX ((1L << 62) - 1)
#define INT_MIN (-(1L << 62))
#endif
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