From 643896e2c8a2a9088819d3410f94008a83f575c6 Mon Sep 17 00:00:00 2001
From: Aryadev Chavali <aryadev@aryadevchavali.com>
Date: Wed, 20 Aug 2025 21:24:07 +0100
Subject: rename base.h -> alisp.h

Makes more sense when you think about including it as an external
library
---
 alisp.h | 167 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 167 insertions(+)
 create mode 100644 alisp.h

(limited to 'alisp.h')

diff --git a/alisp.h b/alisp.h
new file mode 100644
index 0000000..5b7c9e1
--- /dev/null
+++ b/alisp.h
@@ -0,0 +1,167 @@
+/* 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: All the definitions required for the lisp system
+ */
+
+#ifndef ALISP_H
+#define ALISP_H
+
+#include <stdint.h>
+
+/// The bare fucking minimum
+#define MAX(A, B)      ((A) > (B) ? (A) : (B))
+#define MIN(A, B)      ((A) < (B) ? (A) : (B))
+#define ARRSIZE(A)     (sizeof(A) / sizeof((A)[0]))
+#define NTH_BYTE(X, N) (((X) >> (8 * N)) & ((1 << 8) - 1))
+
+typedef uint8_t u8;
+typedef uint16_t u16;
+typedef uint32_t u32;
+typedef uint64_t u64;
+
+typedef int8_t i8;
+typedef int16_t i16;
+typedef int32_t i32;
+typedef int64_t i64;
+
+/// String Views for my String Needs
+typedef struct
+{
+  u64 size;
+  char *data;
+} sv_t;
+
+#define SV(DATA, SIZE) ((sv_t){.data = (DATA), .size = (SIZE)})
+#define SV_FMT(SV)     (int)(SV).size, (SV).data
+#define PR_SV          "%.*s"
+
+sv_t sv_copy(sv_t old);
+
+/// Dynamic arrays
+
+typedef struct
+{
+  u64 size, capacity;
+  u8 bytes[];
+} vec_t;
+
+#define VEC_GET(P)  (((vec_t *)(P)) - 1)
+#define VEC_SIZE(P) (VEC_GET(P)->size)
+#define VEC_CAP(P)  (VEC_GET(P)->capacity)
+#define VEC_MULT    2
+
+void vec_make(void **ptr, u64 size);
+void vec_free(void **data);
+void vec_ensure_remaining(void **ptr, u64 space);
+void vec_append_byte(void **ptr, u8 byte);
+void vec_append(void **ptr, void *data, u64 size);
+void vec_clone(void **dest, void **src);
+
+/// Symbol table
+typedef struct
+{
+  u64 count;     // How many strings?
+  u64 capacity;  // How many entry buckets?
+  sv_t *entries; // this is actually a vector on the inside lol
+} sym_table_t;
+
+#define SYM_TABLE_INIT_SIZE 1024
+
+u64 djb2(sv_t string);
+void sym_table_init(sym_table_t *table);
+char *sym_table_find(sym_table_t *table, sv_t sv);
+void sym_table_cleanup(sym_table_t *table);
+
+/// Basic defintions for a Lisp
+#define NIL 0
+
+typedef struct Obj lisp_t;
+
+typedef struct
+{
+  lisp_t *car, *cdr;
+} cons_t;
+
+typedef struct
+{
+  // 2 levels of indirection... disgusting
+  void *data;
+} lvec_t;
+
+/// System context - essentially something to help with system management
+typedef struct
+{
+  lisp_t *memory;
+  sym_table_t symtable;
+} sys_t;
+
+void sys_init(sys_t *);
+void sys_register(sys_t *sys, lisp_t *ptr);
+void sys_cleanup(sys_t *);
+
+/// Constructors and destructors
+lisp_t *make_int(i64 i);
+lisp_t *make_vec(sys_t *sys, u64 capacity);
+lisp_t *intern(sys_t *sys, sv_t sv);
+lisp_t *cons(sys_t *sys, lisp_t *car, lisp_t *cdr);
+
+i64 as_int(lisp_t *);
+char *as_sym(lisp_t *);
+cons_t *as_cons(lisp_t *);
+void *as_vec(lisp_t *);
+
+#define CAR(L) (as_cons(L)->car)
+#define CDR(L) (as_cons(L)->cdr)
+
+/// Pointer tagging scheme for lisps
+
+typedef enum Tag
+{
+  TAG_NIL  = 0b00000000, // Start of atomic types
+  TAG_INT  = 0b00000001, // special so we can encode 63 bit integers
+  TAG_SYM  = 0b00000100,
+  TAG_CONS = 0b00000010, // Start of container types
+  TAG_VEC  = 0b00000110,
+  NUM_TAGS = 5,
+} tag_t;
+
+enum Shift
+{
+  SHIFT_INT  = 1,
+  SHIFT_SYM  = 8,
+  SHIFT_CONS = 8,
+  SHIFT_VEC  = 8,
+};
+
+enum Mask
+{
+  MASK_INT  = 0b00000001,
+  MASK_SYM  = 0b11111111,
+  MASK_CONS = 0b11111111,
+  MASK_VEC  = 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)
+
+#define INT_MAX ((1L << 62) - 1)
+#define INT_MIN (-(1L << 62))
+
+tag_t get_tag(lisp_t *lisp);
+
+lisp_t *tag_int(i64 i);
+lisp_t *tag_sym(char *str);
+lisp_t *tag_cons(cons_t *cons);
+lisp_t *tag_vec(lvec_t *lvec);
+
+#endif
-- 
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