From ba5c0a4579ece5d53c009a14d00e683e70b982f4 Mon Sep 17 00:00:00 2001
From: Aryadev Chavali <aryadev@aryadevchavali.com>
Date: Fri, 9 May 2025 18:29:52 +0100
Subject: Initial implementation

---
 tag.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 94 insertions(+)
 create mode 100644 tag.c

(limited to 'tag.c')

diff --git a/tag.c b/tag.c
new file mode 100644
index 0000000..5fc03e0
--- /dev/null
+++ b/tag.c
@@ -0,0 +1,94 @@
+/* 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;
+}
-- 
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