added support for NaN boxing (8 byte CValues!)

src/cvalue.h

@@ -4,10 +4,10 @@
 #include "cosmo.h"
 
 typedef enum {
-    COSMO_TNIL,
+    COSMO_TNUMBER, // number has to be 0 because NaN box
     COSMO_TBOOLEAN,
-    COSMO_TNUMBER,
-    COSMO_TOBJ
+    COSMO_TOBJ,
+    COSMO_TNIL,
 } CosmoType;
 
 typedef double cosmo_Number;
@@ -15,6 +15,57 @@ typedef double cosmo_Number;
 /*
     holds primitive cosmo types
 */
+
+#ifdef NAN_BOXXED
+/*
+        NaN box, this is great for performance on x86_64 or ARM64 architectures. If you don't know how this works please reference these
+    two articles:
+
+    https://leonardschuetz.ch/blog/nan-boxing/ and https://piotrduperas.com/posts/nan-boxing/
+
+    both are great resources :)
+
+    TL;DR: we can store payloads in the NaN value in the IEEE 754 standard.
+*/
+typedef union CValue {
+    uint64_t data;
+    cosmo_Number num;
+} CValue;
+
+#define MASK_SIGN_BIT   ((uint64_t)1 << 63)
+#define MASK_TYPE       ((uint64_t)0xf)
+#define MASK_PAYLOAD    ((uint64_t)0xfffffffffff0)
+
+#define MAKE_PAYLOAD(x) ((uint64_t)(x) << 4)
+
+// The bits that must be set to indicate a quiet NaN.
+#define MASK_QUIETNAN        ((uint64_t)0x7ffc000000000000)
+
+// sadly this requires a bit more than a simple macro :(
+static inline CosmoType GET_TYPE(CValue val) {
+    // it's not not a number (its a number)
+    if ((((val.data) & MASK_QUIETNAN) != MASK_QUIETNAN))
+        return COSMO_TNUMBER;
+
+    if ((((val.data) & (MASK_QUIETNAN | MASK_SIGN_BIT)) == (MASK_QUIETNAN | MASK_SIGN_BIT)))
+        return COSMO_TOBJ;
+
+    return (val.data & MASK_TYPE);
+}
+
+#define cosmoV_newNumber(x)     ((CValue){.num = x})
+#define cosmoV_newObj(x)        ((CValue){.data = MASK_SIGN_BIT | MASK_QUIETNAN | (uint64_t)(uintptr_t)(x)})
+#define cosmoV_newBoolean(x)    ((CValue){.data = MASK_QUIETNAN | MAKE_PAYLOAD(x) | COSMO_TBOOLEAN})
+#define cosmoV_newNil()         ((CValue){.data = MASK_QUIETNAN | COSMO_TNIL})
+
+#define cosmoV_readNumber(x)    ((x).num)
+#define cosmoV_readBoolean(x)   ((bool)((x).data & MASK_PAYLOAD))
+#define cosmoV_readObj(x)       (((CObj*)(uintptr_t)(((x).data) & ~(MASK_SIGN_BIT | MASK_QUIETNAN))))
+
+#else
+/*
+    Tagged union, this is the best platform independent solution
+*/
 typedef struct CValue {
     CosmoType type;
     union {
@@ -23,6 +74,29 @@ typedef struct CValue {
         CObj *obj;
     } val;
 } CValue;
+
+#define GET_TYPE(x)     ((x).type)
+
+// create CValues
+
+#define cosmoV_newNumber(x)     ((CValue){COSMO_TNUMBER,    {.num = (x)}})
+#define cosmoV_newBoolean(x)    ((CValue){COSMO_TBOOLEAN,   {.b = (x)}})
+#define cosmoV_newObj(x)        ((CValue){COSMO_TOBJ,       {.obj = (CObj*)(x)}})
+#define cosmoV_newNil()         ((CValue){COSMO_TNIL,       {.num = 0}})
+
+// read CValues
+
+#define cosmoV_readNumber(x)    ((cosmo_Number)(x).val.num)
+#define cosmoV_readBoolean(x)   ((bool)(x).val.b)
+#define cosmoV_readObj(x)       ((CObj*)(x).val.obj)
+
+#endif
+
+#define IS_NUMBER(x)    (GET_TYPE(x) == COSMO_TNUMBER)
+#define IS_BOOLEAN(x)   (GET_TYPE(x) == COSMO_TBOOLEAN)
+#define IS_NIL(x)       (GET_TYPE(x) == COSMO_TNIL)
+#define IS_OBJ(x)       (GET_TYPE(x) == COSMO_TOBJ)
+
 typedef CValue* StkPtr;
 
 typedef struct CValueArray {
@@ -40,22 +114,4 @@ COSMO_API bool cosmoV_equal(CValue valA, CValue valB);
 COSMO_API CObjString *cosmoV_toString(CState *state, CValue val);
 COSMO_API const char *cosmoV_typeStr(CValue val); // return constant char array for corresponding type
 
-#define IS_NUMBER(x)    (x.type == COSMO_TNUMBER)
-#define IS_BOOLEAN(x)   (x.type == COSMO_TBOOLEAN)
-#define IS_NIL(x)       (x.type == COSMO_TNIL)
-#define IS_OBJ(x)       (x.type == COSMO_TOBJ)
-
-// create CValues
-
-#define cosmoV_newNumber(x)     ((CValue){COSMO_TNUMBER, {.num = x}})
-#define cosmoV_newBoolean(x)    ((CValue){COSMO_TBOOLEAN, {.b = x}})
-#define cosmoV_newObj(x)        ((CValue){COSMO_TOBJ, {.obj = (CObj*)x}})
-#define cosmoV_newNil()         ((CValue){COSMO_TNIL, {.num = 0}})
-
-// read CValues
-
-#define cosmoV_readNumber(x)    ((cosmo_Number)x.val.num)
-#define cosmoV_readBoolean(x)   ((bool)x.val.b)
-#define cosmoV_readObj(x)       ((CObj*)x.val.obj)
-
 #endif