1 files changed, 111 insertions, 0 deletions
diff --git a/src/runtime.h b/src/runtime.h
new file mode 100644
index 0000000..dcdb274
--- /dev/null
+++ b/src/runtime.h
@@ -0,0 +1,111 @@
+#ifndef PIT_RUNTIME_H
+#define PIT_RUNTIME_H
+
+#include "types.h"
+#include "utils.h"
+
+typedef struct {
+    i64 elem_size, capacity, next;
+    u8 data[];
+} pit_arena;
+pit_arena *pit_arena_new(i64 capacity, i64 elem_size);
+i32 pit_arena_alloc_idx(pit_arena *a);
+void *pit_arena_alloc(pit_arena *a);
+
+// nil is always the symbol with index 0
+#define PIT_NIL 0b1111111111110100000000000000000000000000000000000000000000000000
+enum pit_value_sort {
+    PIT_VALUE_SORT_DOUBLE  = 0b00, // double
+    PIT_VALUE_SORT_INTEGER = 0b01, // NaN-boxed 49-bit integer
+    PIT_VALUE_SORT_SYMBOL  = 0b10, // NaN-boxed index into symbol table
+    PIT_VALUE_SORT_REF     = 0b11, // NaN-boxed index into "heavy object" arena
+};
+typedef i32 pit_symbol; // a symbol at runtime is an index into the runtime's symbol table
+typedef i32 pit_ref; // a reference is an index into the runtime's arena
+typedef u64 pit_value;
+enum pit_value_sort pit_value_sort(pit_value v);
+u64 pit_value_data(pit_value v);
+
+struct pit_runtime;
+typedef pit_value (*pit_nativefunc)(struct pit_runtime *rt, pit_value args);
+typedef struct { // "heavy" values, the targets of refs
+    enum {
+        PIT_VALUE_HEAVY_SORT_CONS=0,
+        PIT_VALUE_HEAVY_SORT_ARRAY,
+        PIT_VALUE_HEAVY_SORT_BYTES,
+        PIT_VALUE_HEAVY_SORT_NATIVEFUNC,
+    } hsort;
+    union {
+        struct { pit_value car, cdr; } cons;
+        struct { pit_value *data; i64 len; } array;
+        struct { u8 *data; i64 len; } bytes;
+        pit_nativefunc nativefunc;
+    };
+} pit_value_heavy;
+
+typedef struct {
+    pit_value name;
+    pit_value value;
+    pit_value function;
+} pit_symtab_entry;
+
+typedef struct pit_runtime {
+    pit_arena *values;
+    pit_arena *bytes;
+    pit_arena *symtab; i64 symtab_len;
+    pit_value error;
+} pit_runtime;
+
+pit_runtime *pit_runtime_new();
+
+i64 pit_dump(pit_runtime *rt, char *buf, i64 len, pit_value v);
+#define pit_trace(rt, v) pit_trace_(rt, "Trace [" __FILE__ ":" PIT_STR(__LINE__) "] %s\n", v)
+void pit_trace_(pit_runtime *rt, const char *format, pit_value v);
+void pit_error(pit_runtime *rt, const char *format, ...);
+void pit_check_error_maybe_panic(pit_runtime *rt);
+
+// working with small values
+pit_value pit_value_new(pit_runtime *rt, enum pit_value_sort s, u64 data);
+double pit_as_double(pit_runtime *rt, pit_value v);
+pit_value pit_double_new(pit_runtime *rt, double d);
+i64 pit_as_integer(pit_runtime *rt, pit_value v);
+pit_value pit_integer_new(pit_runtime *rt, i64 i);
+pit_symbol pit_as_symbol(pit_runtime *rt, pit_value v);
+pit_value pit_symbol_new(pit_runtime *rt, pit_symbol s);
+pit_ref pit_as_ref(pit_runtime *rt, pit_value v);
+pit_value pit_ref_new(pit_runtime *rt, pit_ref r);
+
+// working with heavy values and refs
+pit_value pit_heavy_new(pit_runtime *rt);
+pit_value_heavy *pit_deref(pit_runtime *rt, pit_ref p);
+
+// convenient predicates
+bool pit_is_cons(pit_runtime *rt, pit_value a);
+bool pit_truthful(pit_value a);
+bool pit_eq(pit_value a, pit_value b);
+bool pit_equal(pit_runtime *rt, pit_value a, pit_value b);
+
+// working with binary data
+pit_value pit_bytes_new(pit_runtime *rt, u8 *buf, i64 len);
+pit_value pit_bytes_new_cstr(pit_runtime *rt, char *s);
+bool pit_bytes_match(pit_runtime *rt, pit_value v, u8 *buf, i64 len);
+
+// working with the symbol table
+pit_value pit_intern(pit_runtime *rt, u8 *nm, i64 len);
+pit_value pit_intern_cstr(pit_runtime *rt, char *nm);
+pit_symtab_entry *pit_symtab_lookup(pit_runtime *rt, pit_value sym);
+pit_value pit_get(pit_runtime *rt, pit_value sym);
+void pit_set(pit_runtime *rt, pit_value sym, pit_value v);
+pit_value pit_fget(pit_runtime *rt, pit_value sym);
+void pit_fset(pit_runtime *rt, pit_value sym, pit_value v);
+
+// working with cons cells
+pit_value pit_cons(pit_runtime *rt, pit_value car, pit_value cdr);
+pit_value pit_list(pit_runtime *rt, i64 num, ...);
+pit_value pit_car(pit_runtime *rt, pit_value v);
+pit_value pit_cdr(pit_runtime *rt, pit_value v);
+
+// working with functions
+pit_value pit_nativefunc_new(pit_runtime *rt, pit_nativefunc f);
+pit_value pit_apply(pit_runtime *rt, pit_value f, pit_value args);
+#endif