internal.h
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internal.h
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	#ifndef ANT_INTERNAL_H
	#define ANT_INTERNAL_H

	#include "ant.h"
	#include "gc.h"

	#include <assert.h>
	#include <string.h>

	typedef struct sv_vm sv_vm_t;
	typedef struct sv_func sv_func_t;

	// An IEEE 754 double-precision float is a 64-bit value with bits laid out like:
	//
	// 1 Sign bit
	// \| 11 Exponent bits
	// \| \| 52 Mantissa (i.e. fraction) bits
	// \| \| \|
	// S[Exponent-][Mantissa------------------------------------------]
	//
	// A NaN is any value where all exponent bits are set and the mantissa is
	// non-zero. That means there are a lot of bit patterns that all represent
	// NaN. NaN tagging takes advantage of this by repurposing those unused
	// patterns to encode non-numeric values.
	//
	// We define a NANBOX_PREFIX as the upper 12 bits all set (0xFFF0...):
	//
	// 1111 1111 1111 0000 0000 0000 ... 0000
	// [sign+exp all 1s ] [mantissa all 0s ]
	//
	// This corresponds to -Infinity in IEEE 754. Any 64-bit value strictly
	// greater than this prefix is a tagged (non-numeric) value. Any value less
	// than or equal to it is an unmodified double — so numeric math is free.
	//
	// For tagged values, we carve the remaining 52 mantissa bits into two fields:
	//
	// 1111 1111 1111 TTTTT DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD
	// [-- prefix ---][type][--------------- 47-bit data --------------------]
	//
	// The 5-bit type tag (bits 51–47) encodes up to 31 distinct types: objects,
	// strings, booleans, undefined, null, functions, closures, errors, etc.
	// The 47-bit data field holds either a heap offset (for heap-resident types
	// like objects and strings) or an immediate value (e.g. 1 for true, 0 for
	// false).
	//
	// Encoding and decoding are simple:
	//
	// mkval(type, data) = PREFIX \| (type << 47) \| (data & 0x7FFFFFFFFFFF)
	// vtype(v) = is_tagged(v) ? (v >> 47) & 0x1F : T_NUM
	// vdata(v) = v & 0x7FFFFFFFFFFF
	// is_tagged(v) = v > PREFIX

	#define NANBOX_TYPE_MASK 0x1F
	#define NANBOX_TYPE_SHIFT 0x2F
	#define NANBOX_HEAP_OFFSET 0x8
	#define NANBOX_PREFIX 0xFFF0000000000000ULL
	#define NANBOX_DATA_MASK 0x00007FFFFFFFFFFFULL

	#define JS_ERR_NO_STACK (1 << 8)
	#define JS_TYPE_FLAG(t) (1u << (t))

	#define MAX_STRINGIFY_DEPTH 64
	#define MAX_PROTO_CHAIN_DEPTH 256
	#define MAX_MULTIREF_OBJS 128
	#define MAX_DENSE_INITIAL_CAP 8

	#define PROTO_WALK_F_OBJECT_ONLY (1u << 0)
	#define PROTO_WALK_F_LOOKUP (1u << 1)

	#define T_EMPTY (NANBOX_PREFIX \| ((jsval_t)T_SENTINEL << NANBOX_TYPE_SHIFT) \| 0xDEADULL)
	#define T_SPECIAL_OBJECT_MASK (JS_TYPE_FLAG(T_OBJ) \| JS_TYPE_FLAG(T_ARR))
	#define T_NEEDS_PROTO_FALLBACK (JS_TYPE_FLAG(T_FUNC) \| JS_TYPE_FLAG(T_ARR) \| JS_TYPE_FLAG(T_PROMISE))
	#define T_OBJECT_MASK (JS_TYPE_FLAG(T_OBJ) \| JS_TYPE_FLAG(T_ARR) \| JS_TYPE_FLAG(T_FUNC) \| JS_TYPE_FLAG(T_PROMISE))
	#define T_NON_NUMERIC_MASK (JS_TYPE_FLAG(T_STR) \| JS_TYPE_FLAG(T_ARR) \| JS_TYPE_FLAG(T_FUNC) \| JS_TYPE_FLAG(T_CFUNC) \| JS_TYPE_FLAG(T_OBJ))

	#define is_non_numeric(v) ((1u << vtype(v)) & T_NON_NUMERIC_MASK)
	#define is_object_type(v) ((1u << vtype(v)) & T_OBJECT_MASK)
	#define is_special_object(v) ((1u << vtype(v)) & T_SPECIAL_OBJECT_MASK)

	enum {
	// heap-resident
	T_OBJ = 0,
	T_PROP = 1,
	T_STR = 2,

	// objects
	T_ARR = 3,
	T_FUNC,
	T_CFUNC,
	T_CLOSURE,
	T_PROMISE,
	T_GENERATOR,

	// primitives
	T_UNDEF,
	T_NULL,
	T_BOOL,
	T_NUM,
	T_BIGINT,
	T_SYMBOL,

	// internal
	T_ERR,
	T_TYPEDARRAY,
	T_FFI,
	T_NTARG,

	T_SENTINEL = 31
	};

	typedef struct {
	const char *src;
	const char *filename;
	jsoff_t src_len;
	jsoff_t off;
	jsoff_t span_len;
	bool valid;
	} js_error_site_t;

	struct ant {
	sv_vm_t *vm;

	#ifdef ANT_JIT
	void *jit_ctx;
	#endif

	const char *code;
	const char *filename;

	uint64_t sym_counter;
	js_error_site_t errsite;

	jsval_t global;
	jsval_t object;
	jsval_t this_val;
	jsval_t new_target;
	jsval_t current_func;

	jsval_t module_ns;
	jsval_t import_meta;
	jsval_t length_str;

	uint8_t *mem;
	jsoff_t size;
	jsoff_t brk;

	struct {
	void *base;
	void *main_base;
	void *main_lo;
	size_t limit;
	} cstk;

	jsoff_t max_size;
	jsval_t thrown_value;
	jsval_t thrown_stack;
	jsoff_t gc_alloc_since;

	jsval_t *gc_roots;
	jshdl_t gc_roots_len;
	jshdl_t gc_roots_cap;

	bool owns_mem;
	bool needs_gc;

	bool fatal_error;
	bool thrown_exists;
	};

	typedef struct {
	const char *ptr;
	size_t len;
	bool needs_free;
	} js_cstr_t;

	typedef struct {
	size_t count;
	size_t bytes;
	} js_intern_stats_t;

	typedef jsval_t
	(js_cfunc_fn_t)(ant_t , jsval_t *, int);

	static inline js_cfunc_fn_t js_as_cfunc(jsval_t fn_val) {
	return (js_cfunc_fn_t)(uintptr_t)vdata(fn_val);
	}

	static inline bool is_err(jsval_t v) {
	return vtype(v) == T_ERR;
	}

	static inline bool is_null(jsval_t v) {
	return vtype(v) == T_NULL;
	}

	static inline bool is_undefined(jsval_t v) {
	return vtype(v) == T_UNDEF;
	}

	static inline bool is_empty_slot(jsval_t v) {
	return v == T_EMPTY;
	}

	static inline jsoff_t loadoff(ant_t *js, jsoff_t off) {
	assert(off + sizeof(jsoff_t) <= js->brk); jsoff_t val;
	memcpy(&val, &js->mem[off], sizeof(val)); return val;
	}

	static inline jsval_t loadval(ant_t *js, jsoff_t off) {
	return (jsval_t )(&js->mem[off]);
	}

	static inline bool is_arr_off(ant_t *js, jsoff_t off) {
	return (loadoff(js, off) & ARRMASK) != 0;
	}

	bool is_internal_prop(const char *key, jsoff_t klen);
	size_t uint_to_str(char *buf, size_t bufsize, uint64_t val);

	void js_gc_reserve_roots(GC_RESERVE_ARGS);
	void js_gc_update_roots(GC_UPDATE_ARGS);
	void js_gc_visit_frame_funcs(ant_t js, void (visitor)(void , sv_func_t ), void *ctx);

	jsoff_t esize(jsoff_t w);
	jsval_t tov(double d);

	double tod(jsval_t v);
	double js_to_number(ant_t *js, jsval_t arg);

	jsval_t resolveprop(ant_t *js, jsval_t v);
	jsval_t mkprop(ant_t *js, jsval_t obj, jsval_t k, jsval_t v, jsoff_t flags);
	jsval_t setprop_cstr(ant_t js, jsval_t obj, const char key, size_t len, jsval_t v);
	jsval_t setprop_interned(ant_t js, jsval_t obj, const char key, size_t len, jsval_t v);
	jsval_t js_define_own_prop(ant_t js, jsval_t obj, const char key, size_t klen, jsval_t v);

	jsval_t coerce_to_str(ant_t *js, jsval_t v);
	jsval_t coerce_to_str_concat(ant_t *js, jsval_t v);
	jsval_t get_ctor_species_value(ant_t *js, jsval_t ctor);

	bool is_rope(ant_t *js, jsval_t value);
	bool proto_chain_contains(ant_t *js, jsval_t obj, jsval_t proto_target);
	bool same_ctor_identity(ant_t *js, jsval_t a, jsval_t b);

	js_intern_stats_t js_intern_stats(void);
	js_cstr_t js_to_cstr(ant_t js, jsval_t value, char stack_buf, size_t stack_size);
	jsval_t js_instance_proto_from_new_target(ant_t *js, jsval_t fallback_proto);

	jsoff_t lkp(ant_t js, jsval_t obj, const char buf, size_t len);
	jsoff_t lkp_proto(ant_t js, jsval_t obj, const char buf, size_t len);
	jsoff_t lkp_sym(ant_t *js, jsval_t obj, jsoff_t sym_off);
	jsoff_t lkp_sym_proto(ant_t *js, jsval_t obj, jsoff_t sym_off);
	jsoff_t vstr(ant_t js, jsval_t value, jsoff_t len);
	jsoff_t vstrlen(ant_t *js, jsval_t value);
	jsval_t rope_flatten(ant_t *js, jsval_t rope);
	jsoff_t str_len_fast(ant_t *js, jsval_t str);

	jsval_t mkarr(ant_t *js);
	jsval_t mkval(uint8_t type, uint64_t data);
	jsval_t mkobj(ant_t *js, jsoff_t parent);

	jsval_t js_for_in_keys(ant_t *js, jsval_t obj);
	jsval_t js_delete_prop(ant_t js, jsval_t obj, const char key, size_t len);
	jsval_t js_delete_sym_prop(ant_t *js, jsval_t obj, jsval_t sym);

	bool is_proxy(ant_t *js, jsval_t obj);
	bool strict_eq_values(ant_t *js, jsval_t l, jsval_t r);

	jsval_t js_proxy_apply(ant_t js, jsval_t proxy, jsval_t this_arg, jsval_t args, int argc);
	jsval_t js_proxy_construct(ant_t js, jsval_t proxy, jsval_t args, int argc, jsval_t new_target);
	jsval_t sv_call_native(ant_t js, jsval_t func, jsval_t this_val, jsval_t args, int nargs);

	const char *typestr(uint8_t t);
	jsval_t unwrap_primitive(ant_t *js, jsval_t val);
	jsval_t do_string_op(ant_t *js, uint8_t op, jsval_t l, jsval_t r);
	jsval_t js_to_primitive(ant_t *js, jsval_t value, int hint);

	jsval_t do_instanceof(ant_t *js, jsval_t l, jsval_t r);
	jsval_t do_in(ant_t *js, jsval_t l, jsval_t r);

	jsval_t bigint_add(ant_t *js, jsval_t a, jsval_t b);
	jsval_t bigint_sub(ant_t *js, jsval_t a, jsval_t b);
	jsval_t bigint_mul(ant_t *js, jsval_t a, jsval_t b);
	jsval_t bigint_div(ant_t *js, jsval_t a, jsval_t b);
	jsval_t bigint_mod(ant_t *js, jsval_t a, jsval_t b);
	jsval_t bigint_neg(ant_t *js, jsval_t a);
	jsval_t bigint_exp(ant_t *js, jsval_t base, jsval_t exp);
	int bigint_compare(ant_t *js, jsval_t a, jsval_t b);

	jsval_t bigint_shift_left(ant_t *js, jsval_t value, uint64_t shift);
	jsval_t bigint_shift_right(ant_t *js, jsval_t value, uint64_t shift);
	jsval_t bigint_shift_right_logical(ant_t *js, jsval_t value, uint64_t shift);
	jsval_t bigint_asint_bits(ant_t js, jsval_t arg, uint64_t bits_out);

	#endif

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