297 lines
11 KiB
C
297 lines
11 KiB
C
/*
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* Heap header definition and assorted macros, including ref counting.
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* Access all fields through the accessor macros.
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*/
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#if !defined(DUK_HEAPHDR_H_INCLUDED)
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#define DUK_HEAPHDR_H_INCLUDED
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/*
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* Common heap header
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*
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* All heap objects share the same flags and refcount fields. Objects other
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* than strings also need to have a single or double linked list pointers
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* for insertion into the "heap allocated" list. Strings have single linked
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* list pointers for string table chaining.
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*
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* Technically, 'h_refcount' must be wide enough to guarantee that it cannot
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* wrap; otherwise objects might be freed incorrectly after wrapping. The
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* default refcount field is 32 bits even on 64-bit systems: while that's in
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* theory incorrect, the Duktape heap needs to be larger than 64GB for the
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* count to actually wrap (assuming 16-byte duk_tvals). This is very unlikely
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* to ever be an issue, but if it is, disabling DUK_USE_REFCOUNT32 causes
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* Duktape to use size_t for refcounts which should always be safe.
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*
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* Heap header size on 32-bit platforms: 8 bytes without reference counting,
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* 16 bytes with reference counting.
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*
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* Note that 'raw' macros such as DUK_HEAPHDR_GET_REFCOUNT() are not
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* defined without DUK_USE_REFERENCE_COUNTING, so caller must #if defined()
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* around them.
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*/
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/* XXX: macro for shared header fields (avoids some padding issues) */
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struct duk_heaphdr {
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duk_uint32_t h_flags;
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#if defined(DUK_USE_REFERENCE_COUNTING)
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#if defined(DUK_USE_ASSERTIONS)
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/* When assertions enabled, used by mark-and-sweep for refcount
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* validation. Largest reasonable type; also detects overflows.
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*/
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duk_size_t h_assert_refcount;
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#endif
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#if defined(DUK_USE_REFCOUNT16)
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duk_uint16_t h_refcount;
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#elif defined(DUK_USE_REFCOUNT32)
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duk_uint32_t h_refcount;
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#else
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duk_size_t h_refcount;
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#endif
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#endif /* DUK_USE_REFERENCE_COUNTING */
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#if defined(DUK_USE_HEAPPTR16)
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duk_uint16_t h_next16;
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#else
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duk_heaphdr *h_next;
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#endif
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#if defined(DUK_USE_DOUBLE_LINKED_HEAP)
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/* refcounting requires direct heap frees, which in turn requires a dual linked heap */
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#if defined(DUK_USE_HEAPPTR16)
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duk_uint16_t h_prev16;
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#else
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duk_heaphdr *h_prev;
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#endif
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#endif
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/* When DUK_USE_HEAPPTR16 (and DUK_USE_REFCOUNT16) is in use, the
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* struct won't align nicely to 4 bytes. This 16-bit extra field
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* is added to make the alignment clean; the field can be used by
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* heap objects when 16-bit packing is used. This field is now
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* conditional to DUK_USE_HEAPPTR16 only, but it is intended to be
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* used with DUK_USE_REFCOUNT16 and DUK_USE_DOUBLE_LINKED_HEAP;
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* this only matter to low memory environments anyway.
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*/
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#if defined(DUK_USE_HEAPPTR16)
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duk_uint16_t h_extra16;
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#endif
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};
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struct duk_heaphdr_string {
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/* 16 bits would be enough for shared heaphdr flags and duk_hstring
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* flags. The initial parts of duk_heaphdr_string and duk_heaphdr
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* must match so changing the flags field size here would be quite
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* awkward. However, to minimize struct size, we can pack at least
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* 16 bits of duk_hstring data into the flags field.
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*/
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duk_uint32_t h_flags;
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#if defined(DUK_USE_REFERENCE_COUNTING)
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#if defined(DUK_USE_ASSERTIONS)
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/* When assertions enabled, used by mark-and-sweep for refcount
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* validation. Largest reasonable type; also detects overflows.
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*/
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duk_size_t h_assert_refcount;
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#endif
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#if defined(DUK_USE_REFCOUNT16)
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duk_uint16_t h_refcount;
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duk_uint16_t h_strextra16; /* round out to 8 bytes */
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#elif defined(DUK_USE_REFCOUNT32)
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duk_uint32_t h_refcount;
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#else
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duk_size_t h_refcount;
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#endif
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#else
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duk_uint16_t h_strextra16;
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#endif /* DUK_USE_REFERENCE_COUNTING */
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duk_hstring *h_next;
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/* No 'h_prev' pointer for strings. */
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};
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#define DUK_HEAPHDR_FLAGS_TYPE_MASK 0x00000003UL
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#define DUK_HEAPHDR_FLAGS_FLAG_MASK (~DUK_HEAPHDR_FLAGS_TYPE_MASK)
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/* 2 bits for heap type */
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#define DUK_HEAPHDR_FLAGS_HEAP_START 2 /* 5 heap flags */
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#define DUK_HEAPHDR_FLAGS_USER_START 7 /* 25 user flags */
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#define DUK_HEAPHDR_HEAP_FLAG_NUMBER(n) (DUK_HEAPHDR_FLAGS_HEAP_START + (n))
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#define DUK_HEAPHDR_USER_FLAG_NUMBER(n) (DUK_HEAPHDR_FLAGS_USER_START + (n))
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#define DUK_HEAPHDR_HEAP_FLAG(n) (1UL << (DUK_HEAPHDR_FLAGS_HEAP_START + (n)))
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#define DUK_HEAPHDR_USER_FLAG(n) (1UL << (DUK_HEAPHDR_FLAGS_USER_START + (n)))
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#define DUK_HEAPHDR_FLAG_REACHABLE DUK_HEAPHDR_HEAP_FLAG(0) /* mark-and-sweep: reachable */
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#define DUK_HEAPHDR_FLAG_TEMPROOT DUK_HEAPHDR_HEAP_FLAG(1) /* mark-and-sweep: children not processed */
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#define DUK_HEAPHDR_FLAG_FINALIZABLE DUK_HEAPHDR_HEAP_FLAG(2) /* mark-and-sweep: finalizable (on current pass) */
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#define DUK_HEAPHDR_FLAG_FINALIZED DUK_HEAPHDR_HEAP_FLAG(3) /* mark-and-sweep: finalized (on previous pass) */
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#define DUK_HEAPHDR_FLAG_READONLY DUK_HEAPHDR_HEAP_FLAG(4) /* read-only object, in code section */
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#define DUK_HTYPE_MIN 0
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#define DUK_HTYPE_STRING 0
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#define DUK_HTYPE_OBJECT 1
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#define DUK_HTYPE_BUFFER 2
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#define DUK_HTYPE_MAX 2
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#if defined(DUK_USE_HEAPPTR16)
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#define DUK_HEAPHDR_GET_NEXT(heap,h) \
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((duk_heaphdr *) DUK_USE_HEAPPTR_DEC16((heap)->heap_udata, (h)->h_next16))
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#define DUK_HEAPHDR_SET_NEXT(heap,h,val) do { \
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(h)->h_next16 = DUK_USE_HEAPPTR_ENC16((heap)->heap_udata, (void *) val); \
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} while (0)
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#else
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#define DUK_HEAPHDR_GET_NEXT(heap,h) ((h)->h_next)
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#define DUK_HEAPHDR_SET_NEXT(heap,h,val) do { \
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(h)->h_next = (val); \
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} while (0)
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#endif
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#if defined(DUK_USE_DOUBLE_LINKED_HEAP)
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#if defined(DUK_USE_HEAPPTR16)
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#define DUK_HEAPHDR_GET_PREV(heap,h) \
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((duk_heaphdr *) DUK_USE_HEAPPTR_DEC16((heap)->heap_udata, (h)->h_prev16))
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#define DUK_HEAPHDR_SET_PREV(heap,h,val) do { \
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(h)->h_prev16 = DUK_USE_HEAPPTR_ENC16((heap)->heap_udata, (void *) (val)); \
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} while (0)
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#else
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#define DUK_HEAPHDR_GET_PREV(heap,h) ((h)->h_prev)
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#define DUK_HEAPHDR_SET_PREV(heap,h,val) do { \
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(h)->h_prev = (val); \
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} while (0)
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#endif
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#endif
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#if defined(DUK_USE_REFERENCE_COUNTING)
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#define DUK_HEAPHDR_GET_REFCOUNT(h) ((h)->h_refcount)
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#define DUK_HEAPHDR_SET_REFCOUNT(h,val) do { \
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(h)->h_refcount = (val); \
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DUK_ASSERT((h)->h_refcount == (val)); /* No truncation. */ \
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} while (0)
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#define DUK_HEAPHDR_PREINC_REFCOUNT(h) (++(h)->h_refcount) /* result: updated refcount */
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#define DUK_HEAPHDR_PREDEC_REFCOUNT(h) (--(h)->h_refcount) /* result: updated refcount */
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#else
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/* refcount macros not defined without refcounting, caller must #if defined() now */
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#endif /* DUK_USE_REFERENCE_COUNTING */
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/*
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* Note: type is treated as a field separate from flags, so some masking is
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* involved in the macros below.
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*/
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#define DUK_HEAPHDR_GET_FLAGS_RAW(h) ((h)->h_flags)
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#define DUK_HEAPHDR_SET_FLAGS_RAW(h,val) do { \
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(h)->h_flags = (val); } \
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}
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#define DUK_HEAPHDR_GET_FLAGS(h) ((h)->h_flags & DUK_HEAPHDR_FLAGS_FLAG_MASK)
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#define DUK_HEAPHDR_SET_FLAGS(h,val) do { \
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(h)->h_flags = ((h)->h_flags & ~(DUK_HEAPHDR_FLAGS_FLAG_MASK)) | (val); \
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} while (0)
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#define DUK_HEAPHDR_GET_TYPE(h) ((h)->h_flags & DUK_HEAPHDR_FLAGS_TYPE_MASK)
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#define DUK_HEAPHDR_SET_TYPE(h,val) do { \
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(h)->h_flags = ((h)->h_flags & ~(DUK_HEAPHDR_FLAGS_TYPE_MASK)) | (val); \
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} while (0)
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/* Comparison for type >= DUK_HTYPE_MIN skipped; because DUK_HTYPE_MIN is zero
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* and the comparison is unsigned, it's always true and generates warnings.
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*/
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#define DUK_HEAPHDR_HTYPE_VALID(h) ( \
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DUK_HEAPHDR_GET_TYPE((h)) <= DUK_HTYPE_MAX \
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)
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#define DUK_HEAPHDR_SET_TYPE_AND_FLAGS(h,tval,fval) do { \
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(h)->h_flags = ((tval) & DUK_HEAPHDR_FLAGS_TYPE_MASK) | \
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((fval) & DUK_HEAPHDR_FLAGS_FLAG_MASK); \
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} while (0)
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#define DUK_HEAPHDR_SET_FLAG_BITS(h,bits) do { \
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DUK_ASSERT(((bits) & ~(DUK_HEAPHDR_FLAGS_FLAG_MASK)) == 0); \
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(h)->h_flags |= (bits); \
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} while (0)
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#define DUK_HEAPHDR_CLEAR_FLAG_BITS(h,bits) do { \
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DUK_ASSERT(((bits) & ~(DUK_HEAPHDR_FLAGS_FLAG_MASK)) == 0); \
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(h)->h_flags &= ~((bits)); \
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} while (0)
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#define DUK_HEAPHDR_CHECK_FLAG_BITS(h,bits) (((h)->h_flags & (bits)) != 0)
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#define DUK_HEAPHDR_SET_REACHABLE(h) DUK_HEAPHDR_SET_FLAG_BITS((h),DUK_HEAPHDR_FLAG_REACHABLE)
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#define DUK_HEAPHDR_CLEAR_REACHABLE(h) DUK_HEAPHDR_CLEAR_FLAG_BITS((h),DUK_HEAPHDR_FLAG_REACHABLE)
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#define DUK_HEAPHDR_HAS_REACHABLE(h) DUK_HEAPHDR_CHECK_FLAG_BITS((h),DUK_HEAPHDR_FLAG_REACHABLE)
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#define DUK_HEAPHDR_SET_TEMPROOT(h) DUK_HEAPHDR_SET_FLAG_BITS((h),DUK_HEAPHDR_FLAG_TEMPROOT)
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#define DUK_HEAPHDR_CLEAR_TEMPROOT(h) DUK_HEAPHDR_CLEAR_FLAG_BITS((h),DUK_HEAPHDR_FLAG_TEMPROOT)
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#define DUK_HEAPHDR_HAS_TEMPROOT(h) DUK_HEAPHDR_CHECK_FLAG_BITS((h),DUK_HEAPHDR_FLAG_TEMPROOT)
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#define DUK_HEAPHDR_SET_FINALIZABLE(h) DUK_HEAPHDR_SET_FLAG_BITS((h),DUK_HEAPHDR_FLAG_FINALIZABLE)
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#define DUK_HEAPHDR_CLEAR_FINALIZABLE(h) DUK_HEAPHDR_CLEAR_FLAG_BITS((h),DUK_HEAPHDR_FLAG_FINALIZABLE)
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#define DUK_HEAPHDR_HAS_FINALIZABLE(h) DUK_HEAPHDR_CHECK_FLAG_BITS((h),DUK_HEAPHDR_FLAG_FINALIZABLE)
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#define DUK_HEAPHDR_SET_FINALIZED(h) DUK_HEAPHDR_SET_FLAG_BITS((h),DUK_HEAPHDR_FLAG_FINALIZED)
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#define DUK_HEAPHDR_CLEAR_FINALIZED(h) DUK_HEAPHDR_CLEAR_FLAG_BITS((h),DUK_HEAPHDR_FLAG_FINALIZED)
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#define DUK_HEAPHDR_HAS_FINALIZED(h) DUK_HEAPHDR_CHECK_FLAG_BITS((h),DUK_HEAPHDR_FLAG_FINALIZED)
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#define DUK_HEAPHDR_SET_READONLY(h) DUK_HEAPHDR_SET_FLAG_BITS((h),DUK_HEAPHDR_FLAG_READONLY)
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#define DUK_HEAPHDR_CLEAR_READONLY(h) DUK_HEAPHDR_CLEAR_FLAG_BITS((h),DUK_HEAPHDR_FLAG_READONLY)
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#define DUK_HEAPHDR_HAS_READONLY(h) DUK_HEAPHDR_CHECK_FLAG_BITS((h),DUK_HEAPHDR_FLAG_READONLY)
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/* get or set a range of flags; m=first bit number, n=number of bits */
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#define DUK_HEAPHDR_GET_FLAG_RANGE(h,m,n) (((h)->h_flags >> (m)) & ((1UL << (n)) - 1UL))
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#define DUK_HEAPHDR_SET_FLAG_RANGE(h,m,n,v) do { \
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(h)->h_flags = \
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((h)->h_flags & (~(((1UL << (n)) - 1UL) << (m)))) \
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| ((v) << (m)); \
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} while (0)
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/* init pointer fields to null */
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#if defined(DUK_USE_DOUBLE_LINKED_HEAP)
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#define DUK_HEAPHDR_INIT_NULLS(h) do { \
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DUK_HEAPHDR_SET_NEXT((h), (void *) NULL); \
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DUK_HEAPHDR_SET_PREV((h), (void *) NULL); \
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} while (0)
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#else
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#define DUK_HEAPHDR_INIT_NULLS(h) do { \
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DUK_HEAPHDR_SET_NEXT((h), (void *) NULL); \
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} while (0)
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#endif
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#define DUK_HEAPHDR_STRING_INIT_NULLS(h) do { \
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(h)->h_next = NULL; \
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} while (0)
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/*
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* Type tests
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*/
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/* Take advantage of the fact that for DUK_HTYPE_xxx numbers the lowest bit
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* is only set for DUK_HTYPE_OBJECT (= 1).
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*/
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#if 0
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#define DUK_HEAPHDR_IS_OBJECT(h) (DUK_HEAPHDR_GET_TYPE((h)) == DUK_HTYPE_OBJECT)
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#endif
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#define DUK_HEAPHDR_IS_OBJECT(h) ((h)->h_flags & 0x01UL)
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#define DUK_HEAPHDR_IS_STRING(h) (DUK_HEAPHDR_GET_TYPE((h)) == DUK_HTYPE_STRING)
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#define DUK_HEAPHDR_IS_BUFFER(h) (DUK_HEAPHDR_GET_TYPE((h)) == DUK_HTYPE_BUFFER)
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/*
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* Assert helpers
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*/
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/* Check that prev/next links are consistent: if e.g. h->prev is != NULL,
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* h->prev->next should point back to h.
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*/
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#if defined(DUK_USE_ASSERTIONS)
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DUK_INTERNAL_DECL void duk_heaphdr_assert_valid_subclassed(duk_heaphdr *h);
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DUK_INTERNAL_DECL void duk_heaphdr_assert_links(duk_heap *heap, duk_heaphdr *h);
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DUK_INTERNAL_DECL void duk_heaphdr_assert_valid(duk_heaphdr *h);
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#define DUK_HEAPHDR_ASSERT_LINKS(heap,h) do { duk_heaphdr_assert_links((heap), (h)); } while (0)
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#define DUK_HEAPHDR_ASSERT_VALID(h) do { duk_heaphdr_assert_valid((h)); } while (0)
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#else
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#define DUK_HEAPHDR_ASSERT_LINKS(heap,h) do {} while (0)
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#define DUK_HEAPHDR_ASSERT_VALID(h) do {} while (0)
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#endif
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#endif /* DUK_HEAPHDR_H_INCLUDED */
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