X-Git-Url: http://git.chise.org/gitweb/?a=blobdiff_plain;f=src%2Flisp-disunion.h;h=f2c321b8365554461c17b2c4d2afb00e95124e97;hb=debb7eb5baa3e6aae77e4fc0b7704887baf3006e;hp=6ca10efe3ece5cdc9e13ec46fd381fba541dacf4;hpb=77dcef404dc78635f6ffa8f71a803d2bc7cc8921;p=chise%2Fxemacs-chise.git diff --git a/src/lisp-disunion.h b/src/lisp-disunion.h index 6ca10ef..f2c321b 100644 --- a/src/lisp-disunion.h +++ b/src/lisp-disunion.h @@ -25,8 +25,6 @@ Boston, MA 02111-1307, USA. */ /* Format of a non-union-type Lisp Object - For the USE_MINIMAL_TAGBITS implementation: - 3 2 1 0 bit 10987654321098765432109876543210 -------------------------------- @@ -39,61 +37,32 @@ Boston, MA 02111-1307, USA. */ -------------------------------- VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVT - For the non-USE_MINIMAL_TAGBITS implementation: - - 3 2 1 0 - bit 10987654321098765432109876543210 - -------------------------------- - TTTMVVVVVVVVVVVVVVVVVVVVVVVVVVVV - - V = value bits - T = type bits - M = mark bits - For integral Lisp types, i.e. integers and characters, the value bits are the Lisp object. - The object is obtained by masking off the type and mark - bits. In the USE_MINIMAL_TAGBITS implementation, bit 1 is - used as a value bit by splitting the Lisp integer type into - two subtypes, Lisp_Type_Int_Even and Lisp_Type_Int_Odd. By + The object is obtained by masking off the type and mark bits. + Bit 1 is used as a value bit by splitting the Lisp integer type + into two subtypes, Lisp_Type_Int_Even and Lisp_Type_Int_Odd. By this trickery we get 31 bits for integers instead of 30. - In the non-USE_MINIMAL_TAGBITS world, Lisp integers are 28 bits, - or more properly (BITS_PER_EMACS_INT - GCTYPEBITS - 1) bits. - For non-integral types, the value bits of a Lisp_Object contain a pointer to a structure containing the object. The pointer is obtained by masking off the type and mark bits. - In the USE_MINIMAL_TAGBITS implementation, all - pointer-based types are coalesced under a single type called + All pointer-based types are coalesced under a single type called Lisp_Type_Record. The type bits for this type are required by the implementation to be 00, just like the least significant bits of word-aligned struct pointers on 32-bit hardware. Because of this, Lisp_Object pointers don't have to be masked and are full-sized. - In the non-USE_MINIMAL_TAGBITS implementation, the type and - mark bits must be masked off and pointers are limited to 28 - bits (really BITS_PER_EMACS_INT - GCTYPEBITS - 1 bits). - - There are no mark bits in the USE_MINIMAL_TAGBITS implementation. + There are no mark bits. Integers and characters don't need to be marked. All other types are lrecord-based, which means they get marked by incrementing their ->implementation pointer. - In the non-USE_MINIMAL_TAGBITS implementation, the markbit is stored - in the Lisp_Object itself. It is stored in the middle so that the - type bits can be obtained by simply shifting them. - - Outside of garbage collection, all mark bits are always zero. - Here is a brief description of the following macros: - XMARKBIT Extract the mark bit (non-USE_MINIMAL_TAGBITS) - XMARK Set the mark bit of this Lisp_Object (non-USE_MINIMAL_TAGBITS) - XUNMARK Clear the mark bit of this Lisp_Object (non-USE_MINIMAL_TAGBITS) XTYPE The type bits of a Lisp_Object XPNTRVAL The value bits of a Lisp_Object storing a pointer XCHARVAL The value bits of a Lisp_Object storing a Emchar @@ -102,48 +71,22 @@ Boston, MA 02111-1307, USA. */ INTP Non-zero if this Lisp_Object an integer? Qzero Lisp Integer 0 EQ Non-zero if two Lisp_Objects are identical - GC_EQ Version of EQ used during garbage collection -*/ + GC_EQ Version of EQ used during garbage collection */ typedef EMACS_INT Lisp_Object; -#ifdef USE_MINIMAL_TAGBITS - -# define Lisp_Type_Int_Bit (Lisp_Type_Int_Even & Lisp_Type_Int_Odd) -# define XUNMARK(x) DO_NOTHING -# define make_obj(vartype, x) ((Lisp_Object) (x)) -# define make_int(x) ((Lisp_Object) (((x) << INT_GCBITS) | Lisp_Type_Int_Bit)) -# define make_char(x) ((Lisp_Object) (((x) << GCBITS) | Lisp_Type_Char)) -# define VALMASK (((1UL << VALBITS) - 1UL) << GCTYPEBITS) -# define XTYPE(x) ((enum Lisp_Type) (((EMACS_UINT)(x)) & ~VALMASK)) -# define XPNTRVAL(x) (x) /* This depends on Lisp_Type_Record == 0 */ -# define XCHARVAL(x) ((x) >> GCBITS) -# define GC_EQ(x,y) EQ (x,y) -# define XREALINT(x) ((x) >> INT_GCBITS) -# define XUINT(x) ((EMACS_UINT)(x) >> INT_GCBITS) -# define INTP(x) ((EMACS_UINT)(x) & Lisp_Type_Int_Bit) - -#else /* !USE_MINIMAL_TAGBITS */ - -# define MARKBIT (1UL << VALBITS) -# define XMARKBIT(x) (((x) & MARKBIT) != 0) -# define XMARK(x) ((void) ((x) |= MARKBIT)) -# define XUNMARK(x) ((void) ((x) &= ~MARKBIT)) -# define make_obj(vartype, value) \ - ((Lisp_Object) (((EMACS_UINT) (vartype) << (VALBITS + GCMARKBITS)) \ - + ((EMACS_UINT) (value) & VALMASK))) -# define make_int(value) make_obj (Lisp_Type_Int, value) -# define make_char(value) make_obj (Lisp_Type_Char, value) -# define VALMASK ((1UL << VALBITS) - 1UL) -# define XTYPE(x) ((enum Lisp_Type) (((EMACS_UINT)(x)) >> (VALBITS + GCMARKBITS))) -# define XPNTRVAL(x) ((x) & VALMASK) -# define XCHARVAL(x) XPNTRVAL(x) -# define GC_EQ(x,y) (((x) & ~MARKBIT) == ((y) & ~MARKBIT)) -# define XREALINT(x) (((x) << INT_GCBITS) >> INT_GCBITS) -# define XUINT(x) ((EMACS_UINT) ((x) & VALMASK)) -# define INTP(x) (XTYPE (x) == Lisp_Type_Int) - -#endif /* !USE_MINIMAL_TAGBITS */ +#define Lisp_Type_Int_Bit (Lisp_Type_Int_Even & Lisp_Type_Int_Odd) +#define make_obj(vartype, x) ((Lisp_Object) (x)) +#define make_int(x) ((Lisp_Object) (((x) << INT_GCBITS) | Lisp_Type_Int_Bit)) +#define make_char(x) ((Lisp_Object) (((x) << GCBITS) | Lisp_Type_Char)) +#define VALMASK (((1UL << VALBITS) - 1UL) << GCTYPEBITS) +#define XTYPE(x) ((enum Lisp_Type) (((EMACS_UINT)(x)) & ~VALMASK)) +#define XPNTRVAL(x) (x) /* This depends on Lisp_Type_Record == 0 */ +#define XCHARVAL(x) ((x) >> GCBITS) +#define GC_EQ(x,y) EQ (x,y) +#define XREALINT(x) ((x) >> INT_GCBITS) +#define XUINT(x) ((EMACS_UINT)(x) >> INT_GCBITS) +#define INTP(x) ((EMACS_UINT)(x) & Lisp_Type_Int_Bit) #define Qzero make_int (0) #define Qnull_pointer ((Lisp_Object) 0)