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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 Unlicense for details.
* You may distribute and modify this code under the terms of the Unlicense,
* which you should have received a copy of along with this program. If not,
* please go to <https://unlicense.org/>.
* Created: 2025-08-19
* Description: Pointer tagging
*/
#include <assert.h>
#include <stdlib.h>
#include "./base.h"
lisp_t *tag_int(i64 i)
{
return TAG((u64)i, INT);
}
lisp_t *tag_sym(char *str)
{
return TAG((u64)str, SYM);
}
lisp_t *tag_vec(lvec_t *lvec)
{
return TAG((u64)lvec, VEC);
}
lisp_t *tag_cons(cons_t *cons)
{
return TAG((u64)cons, CONS);
}
tag_t get_tag(lisp_t *lisp)
{
static_assert(NUM_TAGS == 5);
if (!lisp)
return TAG_NIL;
else if (IS_TAG(lisp, INT))
return TAG_INT;
return (u64)lisp & 0xFF;
}
i64 as_int(lisp_t *obj)
{
assert(IS_TAG(obj, INT));
u64 p_obj = (u64)obj;
return UNTAG(p_obj, INT) | // Delete the tag
(NTH_BYTE(p_obj, 7) & 0x80) << 56 // duplicate the MSB (preserve sign)
;
}
char *as_sym(lisp_t *obj)
{
assert(IS_TAG(obj, SYM));
return (char *)UNTAG(obj, SYM);
}
cons_t *as_cons(lisp_t *obj)
{
assert(IS_TAG(obj, CONS));
return (cons_t *)UNTAG(obj, CONS);
}
void *as_vec(lisp_t *obj)
{
assert(IS_TAG(obj, VEC));
lvec_t *vec = (lvec_t *)UNTAG(obj, VEC);
if (vec)
return vec->data;
else
return NULL;
}
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