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Diffstat (limited to 'alisp.h')
| -rw-r--r-- | alisp.h | 167 |
1 files changed, 167 insertions, 0 deletions
@@ -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 |