[INFO] Buffer/PMC unification

[Leopold Toetsch]

I will start $subject soon. This will generate a lot of changes in CVS.
The basic common structure will be a Parrot Object or PObj for short.

To get there, the first step will be hiding affected structure members inside some accessor macros and unification of PMC/Buffer flags.

(When this is done, changing below structures to our needs should be really simple)

The involved structures will be something like this finally:

typedef union UnionVal {
struct { /* for 32 bit ints, 64 bit double */
Parrot_Int int_val[2]; /* the 2nd int_val might be useful for */
} i; /* e.g. {nom/denom} floats */
Parrot_Float num_val; /* PMCs UnionVal members */
Parrot_Pointer struct_val;
struct STRING* string_val;
struct PMC* pmc_val;
struct { /* Buffers structure */
void * bufstart;
size_t buflen;
} b;
} UnionVal;

/* Parrot Object - base class for all others */
typedef struct PObj {
UnionVal u;
Parrot_UInt flags;
} PObj;

/* plain Buffer is the smallest Parrot Obj */
typedef struct Buffer {
PObj o;
} Buffer;

/* a scalar PMC is a Parrot Object with a VTABLE */
typedef struct PMC {
PObj o;
nVTABLE *vtable;
} PMC;

For the full story please read (again) these threads starting with
Subjects:
- [RFC] Buffer/PMC unification, variable/value vtable split, tied scalars
- Of PMCs Buffers and memory management

leo