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gpgscm: Provide framework for immediate values. 

* tests/gpgscm/scheme.c (IMMEDIATE_TAG): New macro.
({is,set,clr}_immediate): Likewise.
(enum scheme_types): Make type tags disjoint from immediate values.
(TYPE_BITS): We need one more bit now.
(ADJ,T_MASKTYPE): Compute values.
--
Immediate values are disjoint from all type tags and pointers,
allowing us to store immediate values in all memory locations.

Signed-off-by: Justus Winter <justus@g10code.com>
This commit is contained in:
Justus Winter 2017-01-30 15:45:13 +01:00
parent d27a4435bd
commit e343984fc5
1 changed files with 39 additions and 23 deletions
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62
tests/gpgscm/scheme.c
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@ -111,27 +111,43 @@ static const char *strlwr(char *s) {
# define FIRST_CELLSEGS 3 # define FIRST_CELLSEGS 3
#endif #endif
/* Support for immediate values.
*
* Immediate values are tagged with IMMEDIATE_TAG, which is neither
* used in types, nor in pointer values.
*
* XXX: Currently, we only use this to tag pointers in vectors. */
#define IMMEDIATE_TAG 1
#define is_immediate(p) ((pointer) ((uintptr_t) (p) & IMMEDIATE_TAG))
#define set_immediate(p) ((pointer) ((uintptr_t) (p) | IMMEDIATE_TAG))
#define clr_immediate(p) ((pointer) ((uintptr_t) (p) & ~IMMEDIATE_TAG))
enum scheme_types { enum scheme_types {
T_STRING=1, T_STRING=1 << 1, /* Do not use the lsb, it is used for
T_NUMBER=2, * immediate values. */
T_SYMBOL=3, T_NUMBER=2 << 1,
T_PROC=4, T_SYMBOL=3 << 1,
T_PAIR=5, T_PROC=4 << 1,
T_CLOSURE=6, T_PAIR=5 << 1,
T_CONTINUATION=7, T_CLOSURE=6 << 1,
T_FOREIGN=8, T_CONTINUATION=7 << 1,
T_CHARACTER=9, T_FOREIGN=8 << 1,
T_PORT=10, T_CHARACTER=9 << 1,
T_VECTOR=11, T_PORT=10 << 1,
T_MACRO=12, T_VECTOR=11 << 1,
T_PROMISE=13, T_MACRO=12 << 1,
T_ENVIRONMENT=14, T_PROMISE=13 << 1,
T_FOREIGN_OBJECT=15, T_ENVIRONMENT=14 << 1,
T_BOOLEAN=16, T_FOREIGN_OBJECT=15 << 1,
T_NIL=17, T_BOOLEAN=16 << 1,
T_EOF_OBJ=18, T_NIL=17 << 1,
T_SINK=19, T_EOF_OBJ=18 << 1,
T_LAST_SYSTEM_TYPE=19 T_SINK=19 << 1,
T_LAST_SYSTEM_TYPE=19 << 1
}; };
static const char * static const char *
@ -163,9 +179,9 @@ type_to_string (enum scheme_types typ)
} }
/* ADJ is enough slack to align cells in a TYPE_BITS-bit boundary */ /* ADJ is enough slack to align cells in a TYPE_BITS-bit boundary */
#define ADJ 32 #define TYPE_BITS 6
#define TYPE_BITS 5 #define ADJ (1 << TYPE_BITS)
#define T_MASKTYPE 31 /* 0000000000011111 */ #define T_MASKTYPE (ADJ - 1)
#define T_TAGGED 1024 /* 0000010000000000 */ #define T_TAGGED 1024 /* 0000010000000000 */
#define T_FINALIZE 2048 /* 0000100000000000 */ #define T_FINALIZE 2048 /* 0000100000000000 */
#define T_SYNTAX 4096 /* 0001000000000000 */ #define T_SYNTAX 4096 /* 0001000000000000 */