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Add support for (strong) boxes, value vectors, and byte strings.

This commit is contained in:
Jesse D. McDonald 2009-10-24 19:49:08 -05:00
parent a464397e64
commit 61b83a1293
1 changed files with 55 additions and 19 deletions
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74
gc.c
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@ -5,6 +5,7 @@
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#ifndef NDEBUG
@ -20,14 +21,17 @@ typedef uintptr_t value_t;
/* Object: aaaaaaaa aaaaaaaa aaaaaaaa aaaaaa10 */
/* Fixnum: snnnnnnn nnnnnnnn nnnnnnnn nnnnnnn1 */
#define NIL ((value_t)0)
/* Special values (1 <= n < 1024) */
/* Special values (0 <= n < 1024) */
/* These correspond to pairs within the first page of memory */
#define SPECIAL_VALUE(n) ((value_t)(4*n))
#define MAX_SPECIAL SPECIAL_VALUE(1023)
#define NIL SPECIAL_VALUE(0)
#define BROKEN_HEART SPECIAL_VALUE(1)
#define TYPE_TAG_BOX SPECIAL_VALUE(2)
#define TYPE_TAG_VECTOR SPECIAL_VALUE(3)
#define TYPE_TAG_BYTESTR SPECIAL_VALUE(4)
typedef struct pair
{
@ -44,6 +48,20 @@ typedef struct object
} payload;
} object_t;
typedef struct vector
{
value_t tag;
size_t size;
value_t elements[0];
} vector_t;
typedef struct byte_string
{
value_t tag;
size_t size;
uint8_t bytes[0];
} byte_string_t;
typedef struct gc_root
{
value_t value;
@ -81,7 +99,7 @@ static inline value_t pair_value(pair_t *p)
return (value_t)p;
}
static inline value_t object_value(object_t *obj)
static inline value_t object_value(void *obj)
{
return (value_t)obj | 2;
}
@ -237,11 +255,26 @@ static void transfer_object(value_t *value)
{
switch (obj->tag)
{
#if 0
case TYPE_TAG_VECTOR:
{
const vector_t *vec = (const vector_t*)obj;
const size_t nbytes = sizeof(vector_t) + sizeof(value_t) * vec->size;
vector_t *newvec = (vector_t*)gc_alloc(nbytes);
memcpy(newvec, vec, nbytes);
new_value = object_value(newvec);
}
break;
#endif
default: /* pair or compatible */
case TYPE_TAG_BYTESTR:
{
const byte_string_t *str = (const byte_string_t*)obj;
const size_t nbytes = sizeof(byte_string_t) + str->size;
byte_string_t *newstr = (byte_string_t*)gc_alloc(nbytes);
memcpy(newstr, str, nbytes);
new_value = object_value(newstr);
}
break;
case TYPE_TAG_BOX:
default: /* pair */
{
pair_t *p = (pair_t*)gc_alloc(sizeof(pair_t));
const pair_t *q = (const pair_t*)obj;
@ -250,14 +283,7 @@ static void transfer_object(value_t *value)
//debug(("Moved pair from 0x%0.8X to 0x%0.8X.\n", q, p));
/* Keep the original tag bits (pair or object) */
#if 0
if (is_pair(*value))
new_value = pair_value(p);
else
new_value = object_value((object_t*)p);
#else
new_value = pair_value(p) | (*value & 2);
#endif
}
break;
}
@ -288,16 +314,26 @@ static inline size_t transfer_children(object_t *obj)
{
switch (obj->tag)
{
#if 0 /* Don't support other kinds of GC objects yet */
case TYPE_TAG_VECTOR:
{
return sizeof(*obj) +
sizeof(value_t) * from_fixnum(obj->payload.values[0]);
vector_t *vec = (vector_t*)obj;
const intptr_t nelem = from_fixnum(vec->size);
for (intptr_t i = 0; i < nelem; ++i)
{
transfer_object(&vec->elements[i]);
}
return sizeof(vector_t) + (nelem * sizeof(value_t));
}
#endif
default:
case TYPE_TAG_BYTESTR:
{
const byte_string_t *str = (const byte_string_t*)obj;
return sizeof(byte_string_t) + from_fixnum(str->size);
}
case TYPE_TAG_BOX:
default: /* pair */
{
/* Object is a pair or compatible type (e.g. box) */
pair_t *p = (pair_t*)obj;
transfer_object(&p->car);
transfer_object(&p->cdr);