Aryadev Chavali
7ac2a80b11
Copied from oats, just the basics required for tagging integers or symbols.
43 lines
999 B
C
43 lines
999 B
C
/* Copyright (C) 2025 Aryadev Chavali
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the Unlicense for details.
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* You may distribute and modify this code under the terms of the Unlicense,
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* which you should have received a copy of along with this program. If not,
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* please go to <https://unlicense.org/>.
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* Created: 2025-08-19
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* Description: Pointer tagging
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*/
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#include <assert.h>
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#include "./base.h"
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lisp_t *tag_int(i64 i)
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{
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return TAG((u64)i, INT);
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}
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lisp_t *tag_sym(char *str)
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{
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return TAG((u64)str, SYM);
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}
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i64 as_int(lisp_t *obj)
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{
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assert(IS_TAG(obj, INT));
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u64 p_obj = (u64)obj;
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return UNTAG(p_obj, INT) | // Delete the tag
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(NTH_BYTE(p_obj, 7) & 0x80) << 56 // duplicate the MSB (preserve sign)
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;
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}
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char *as_sym(lisp_t *obj)
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{
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assert(IS_TAG(obj, SYM));
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return (char *)UNTAG(obj, SYM);
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}
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