From 7ac2a80b1143fac9190bbe62811ecc32403bfb98 Mon Sep 17 00:00:00 2001 From: Aryadev Chavali Date: Tue, 19 Aug 2025 23:06:37 +0100 Subject: Pointer tagging! Copied from oats, just the basics required for tagging integers or symbols. --- tag.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 tag.c (limited to 'tag.c') diff --git a/tag.c b/tag.c new file mode 100644 index 0000000..7688d63 --- /dev/null +++ b/tag.c @@ -0,0 +1,42 @@ +/* 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 . + + * Created: 2025-08-19 + * Description: Pointer tagging + */ + +#include + +#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); +} + +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); +} -- cgit v1.2.3-13-gbd6f