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/*
* Heap buffer representation.
*
* Heap allocated user data buffer which is either:
*
* 1. A fixed size buffer (data follows header statically)
* 2. A dynamic size buffer (data pointer follows header)
*
* The data pointer for a variable size buffer of zero size may be NULL.
*/
#ifndef DUK_HBUFFER_H_INCLUDED
#define DUK_HBUFFER_H_INCLUDED
/*
* Flags
*
* Fixed buffer: 0
* Dynamic buffer: DUK_HBUFFER_FLAG_DYNAMIC
* External buffer: DUK_HBUFFER_FLAG_DYNAMIC | DUK_HBUFFER_FLAG_EXTERNAL
*/
#define DUK_HBUFFER_FLAG_DYNAMIC DUK_HEAPHDR_USER_FLAG(0) /* buffer is behind a pointer, dynamic or external */
#define DUK_HBUFFER_FLAG_EXTERNAL DUK_HEAPHDR_USER_FLAG(1) /* buffer pointer is to an externally allocated buffer */
#define DUK_HBUFFER_HAS_DYNAMIC(x) DUK_HEAPHDR_CHECK_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_DYNAMIC)
#define DUK_HBUFFER_HAS_EXTERNAL(x) DUK_HEAPHDR_CHECK_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_EXTERNAL)
#define DUK_HBUFFER_SET_DYNAMIC(x) DUK_HEAPHDR_SET_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_DYNAMIC)
#define DUK_HBUFFER_SET_EXTERNAL(x) DUK_HEAPHDR_SET_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_EXTERNAL)
#define DUK_HBUFFER_CLEAR_DYNAMIC(x) DUK_HEAPHDR_CLEAR_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_DYNAMIC)
#define DUK_HBUFFER_CLEAR_EXTERNAL(x) DUK_HEAPHDR_CLEAR_FLAG_BITS(&(x)->hdr, DUK_HBUFFER_FLAG_EXTERNAL)
/*
* Misc defines
*/
/* Impose a maximum buffer length for now. Restricted artificially to
* ensure resize computations or adding a heap header length won't
* overflow size_t and that a signed duk_int_t can hold a buffer
* length. The limit should be synchronized with DUK_HSTRING_MAX_BYTELEN.
*/
#if defined(DUK_USE_BUFLEN16)
#define DUK_HBUFFER_MAX_BYTELEN (0x0000ffffUL)
#else
/* Intentionally not 0x7fffffffUL; at least JSON code expects that
* 2*len + 2 fits in 32 bits.
*/
#define DUK_HBUFFER_MAX_BYTELEN (0x7ffffffeUL)
#endif
/*
* Field access
*/
/* Get/set the current user visible size, without accounting for a dynamic
* buffer's "spare" (= usable size).
*/
#if defined(DUK_USE_BUFLEN16)
/* size stored in duk_heaphdr unused flag bits */
#define DUK_HBUFFER_GET_SIZE(x) ((x)->hdr.h_flags >> 16)
#define DUK_HBUFFER_SET_SIZE(x,v) do { \
duk_size_t duk__v; \
duk__v = (v); \
DUK_ASSERT(duk__v <= 0xffffUL); \
(x)->hdr.h_flags = ((x)->hdr.h_flags & 0x0000ffffUL) | (((duk_uint32_t) duk__v) << 16); \
} while (0)
#define DUK_HBUFFER_ADD_SIZE(x,dv) do { \
(x)->hdr.h_flags += ((dv) << 16); \
} while (0)
#define DUK_HBUFFER_SUB_SIZE(x,dv) do { \
(x)->hdr.h_flags -= ((dv) << 16); \
} while (0)
#else
#define DUK_HBUFFER_GET_SIZE(x) (((duk_hbuffer *) (x))->size)
#define DUK_HBUFFER_SET_SIZE(x,v) do { \
((duk_hbuffer *) (x))->size = (v); \
} while (0)
#define DUK_HBUFFER_ADD_SIZE(x,dv) do { \
(x)->size += (dv); \
} while (0)
#define DUK_HBUFFER_SUB_SIZE(x,dv) do { \
(x)->size -= (dv); \
} while (0)
#endif
#define DUK_HBUFFER_FIXED_GET_SIZE(x) DUK_HBUFFER_GET_SIZE((duk_hbuffer *) (x))
#define DUK_HBUFFER_FIXED_SET_SIZE(x,v) DUK_HBUFFER_SET_SIZE((duk_hbuffer *) (x))
#define DUK_HBUFFER_DYNAMIC_GET_SIZE(x) DUK_HBUFFER_GET_SIZE((duk_hbuffer *) (x))
#define DUK_HBUFFER_DYNAMIC_SET_SIZE(x,v) DUK_HBUFFER_SET_SIZE((duk_hbuffer *) (x), (v))
#define DUK_HBUFFER_DYNAMIC_ADD_SIZE(x,dv) DUK_HBUFFER_ADD_SIZE((duk_hbuffer *) (x), (dv))
#define DUK_HBUFFER_DYNAMIC_SUB_SIZE(x,dv) DUK_HBUFFER_SUB_SIZE((duk_hbuffer *) (x), (dv))
#define DUK_HBUFFER_EXTERNAL_GET_SIZE(x) DUK_HBUFFER_GET_SIZE((duk_hbuffer *) (x))
#define DUK_HBUFFER_EXTERNAL_SET_SIZE(x,v) DUK_HBUFFER_SET_SIZE((duk_hbuffer *) (x), (v))
#define DUK_HBUFFER_FIXED_GET_DATA_PTR(heap,x) ((duk_uint8_t *) (((duk_hbuffer_fixed *) (x)) + 1))
#if defined(DUK_USE_HEAPPTR16)
#define DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(heap,x) \
((void *) DUK_USE_HEAPPTR_DEC16((heap)->heap_udata, ((duk_heaphdr *) (x))->h_extra16))
#define DUK_HBUFFER_DYNAMIC_SET_DATA_PTR(heap,x,v) do { \
((duk_heaphdr *) (x))->h_extra16 = DUK_USE_HEAPPTR_ENC16((heap)->heap_udata, (void *) (v)); \
} while (0)
#define DUK_HBUFFER_DYNAMIC_SET_DATA_PTR_NULL(heap,x) do { \
((duk_heaphdr *) (x))->h_extra16 = 0; /* assume 0 <=> NULL */ \
} while (0)
#else
#define DUK_HBUFFER_DYNAMIC_GET_DATA_PTR(heap,x) ((x)->curr_alloc)
#define DUK_HBUFFER_DYNAMIC_SET_DATA_PTR(heap,x,v) do { \
(x)->curr_alloc = (void *) (v); \
} while (0)
#define DUK_HBUFFER_DYNAMIC_SET_DATA_PTR_NULL(heap,x) do { \
(x)->curr_alloc = (void *) NULL; \
} while (0)
#endif
/* No pointer compression because pointer is potentially outside of
* Duktape heap.
*/
#if defined(DUK_USE_HEAPPTR16)
#define DUK_HBUFFER_EXTERNAL_GET_DATA_PTR(heap,x) \
((void *) (x)->curr_alloc)
#define DUK_HBUFFER_EXTERNAL_SET_DATA_PTR(heap,x,v) do { \
(x)->curr_alloc = (void *) (v); \
} while (0)
#define DUK_HBUFFER_EXTERNAL_SET_DATA_PTR_NULL(heap,x) do { \
(x)->curr_alloc = (void *) NULL; \
} while (0)
#else
#define DUK_HBUFFER_EXTERNAL_GET_DATA_PTR(heap,x) \
((void *) (x)->curr_alloc)
#define DUK_HBUFFER_EXTERNAL_SET_DATA_PTR(heap,x,v) do { \
(x)->curr_alloc = (void *) (v); \
} while (0)
#define DUK_HBUFFER_EXTERNAL_SET_DATA_PTR_NULL(heap,x) do { \
(x)->curr_alloc = (void *) NULL; \
} while (0)
#endif
/* Get a pointer to the current buffer contents (matching current allocation
* size). May be NULL for zero size dynamic/external buffer.
*/
#if defined(DUK_USE_HEAPPTR16)
#define DUK_HBUFFER_GET_DATA_PTR(heap,x) ( \
DUK_HBUFFER_HAS_DYNAMIC((x)) ? \
( \
DUK_HBUFFER_HAS_EXTERNAL((x)) ? \
DUK_HBUFFER_EXTERNAL_GET_DATA_PTR((heap), (duk_hbuffer_external *) (x)) : \
DUK_HBUFFER_DYNAMIC_GET_DATA_PTR((heap), (duk_hbuffer_dynamic *) (x)) \
) : \
DUK_HBUFFER_FIXED_GET_DATA_PTR((heap), (duk_hbuffer_fixed *) (x)) \
)
#else
/* Without heap pointer compression duk_hbuffer_dynamic and duk_hbuffer_external
* have the same layout so checking for fixed vs. dynamic (or external) is enough.
*/
#define DUK_HBUFFER_GET_DATA_PTR(heap,x) ( \
DUK_HBUFFER_HAS_DYNAMIC((x)) ? \
DUK_HBUFFER_DYNAMIC_GET_DATA_PTR((heap), (duk_hbuffer_dynamic *) (x)) : \
DUK_HBUFFER_FIXED_GET_DATA_PTR((heap), (duk_hbuffer_fixed *) (x)) \
)
#endif
/*
* Structs
*/
/* Shared prefix for all buffer types. */
struct duk_hbuffer {
duk_heaphdr hdr;
/* It's not strictly necessary to track the current size, but
* it is useful for writing robust native code.
*/
/* Current size (not counting a dynamic buffer's "spare"). */
#if defined(DUK_USE_BUFLEN16)
/* Stored in duk_heaphdr unused flags. */
#else
duk_size_t size;
#endif
/*
* Data following the header depends on the DUK_HBUFFER_FLAG_DYNAMIC
* flag.
*
* If the flag is clear (the buffer is a fixed size one), the buffer
* data follows the header directly, consisting of 'size' bytes.
*
* If the flag is set, the actual buffer is allocated separately, and
* a few control fields follow the header. Specifically:
*
* - a "void *" pointing to the current allocation
* - a duk_size_t indicating the full allocated size (always >= 'size')
*
* If DUK_HBUFFER_FLAG_EXTERNAL is set, the buffer has been allocated
* by user code, so that Duktape won't be able to resize it and won't
* free it. This allows buffers to point to e.g. an externally
* allocated structure such as a frame buffer.
*
* Unlike strings, no terminator byte (NUL) is guaranteed after the
* data. This would be convenient, but would pad aligned user buffers
* unnecessarily upwards in size. For instance, if user code requested
* a 64-byte dynamic buffer, 65 bytes would actually be allocated which
* would then potentially round upwards to perhaps 68 or 72 bytes.
*/
};
/* Fixed buffer; data follows struct, with proper alignment guaranteed by
* struct size.
*/
#if (DUK_USE_ALIGN_BY == 8) && defined(DUK_USE_PACK_MSVC_PRAGMA)
#pragma pack(push, 8)
#endif
struct duk_hbuffer_fixed {
/* A union is used here as a portable struct size / alignment trick:
* by adding a 32-bit or a 64-bit (unused) union member, the size of
* the struct is effectively forced to be a multiple of 4 or 8 bytes
* (respectively) without increasing the size of the struct unless
* necessary.
*/
union {
struct {
duk_heaphdr hdr;
#if defined(DUK_USE_BUFLEN16)
/* Stored in duk_heaphdr unused flags. */
#else
duk_size_t size;
#endif
} s;
#if (DUK_USE_ALIGN_BY == 4)
duk_uint32_t dummy_for_align4;
#elif (DUK_USE_ALIGN_BY == 8)
duk_double_t dummy_for_align8;
#elif (DUK_USE_ALIGN_BY == 1)
/* no extra padding */
#else
#error invalid DUK_USE_ALIGN_BY
#endif
} u;
/*
* Data follows the struct header. The struct size is padded by the
* compiler based on the struct members. This guarantees that the
* buffer data will be aligned-by-4 but not necessarily aligned-by-8.
*
* On platforms where alignment does not matter, the struct padding
* could be removed (if there is any). On platforms where alignment
* by 8 is required, the struct size must be forced to be a multiple
* of 8 by some means. Without it, some user code may break, and also
* Duktape itself breaks (e.g. the compiler stores duk_tvals in a
* dynamic buffer).
*/
}
#if (DUK_USE_ALIGN_BY == 8) && defined(DUK_USE_PACK_GCC_ATTR)
__attribute__ ((aligned (8)))
#elif (DUK_USE_ALIGN_BY == 8) && defined(DUK_USE_PACK_CLANG_ATTR)
__attribute__ ((aligned (8)))
#endif
;
#if (DUK_USE_ALIGN_BY == 8) && defined(DUK_USE_PACK_MSVC_PRAGMA)
#pragma pack(pop)
#endif
/* Dynamic buffer with 'curr_alloc' pointing to a dynamic area allocated using
* heap allocation primitives. Also used for external buffers when low memory
* options are not used.
*/
struct duk_hbuffer_dynamic {
duk_heaphdr hdr;
#if defined(DUK_USE_BUFLEN16)
/* Stored in duk_heaphdr unused flags. */
#else
duk_size_t size;
#endif
#if defined(DUK_USE_HEAPPTR16)
/* Stored in duk_heaphdr h_extra16. */
#else
void *curr_alloc; /* may be NULL if alloc_size == 0 */
#endif
/*
* Allocation size for 'curr_alloc' is alloc_size. There is no
* automatic NUL terminator for buffers (see above for rationale).
*
* 'curr_alloc' is explicitly allocated with heap allocation
* primitives and will thus always have alignment suitable for
* e.g. duk_tval and an IEEE double.
*/
};
/* External buffer with 'curr_alloc' managed by user code and pointing to an
* arbitrary address. When heap pointer compression is not used, this struct
* has the same layout as duk_hbuffer_dynamic.
*/
struct duk_hbuffer_external {
duk_heaphdr hdr;
#if defined(DUK_USE_BUFLEN16)
/* Stored in duk_heaphdr unused flags. */
#else
duk_size_t size;
#endif
/* Cannot be compressed as a heap pointer because may point to
* an arbitrary address.
*/
void *curr_alloc; /* may be NULL if alloc_size == 0 */
};
/*
* Prototypes
*/
DUK_INTERNAL_DECL duk_hbuffer *duk_hbuffer_alloc(duk_heap *heap, duk_size_t size, duk_small_uint_t flags, void **out_bufdata);
DUK_INTERNAL_DECL void *duk_hbuffer_get_dynalloc_ptr(duk_heap *heap, void *ud); /* indirect allocs */
/* dynamic buffer ops */
DUK_INTERNAL_DECL void duk_hbuffer_resize(duk_hthread *thr, duk_hbuffer_dynamic *buf, duk_size_t new_size);
DUK_INTERNAL_DECL void duk_hbuffer_reset(duk_hthread *thr, duk_hbuffer_dynamic *buf);
#endif /* DUK_HBUFFER_H_INCLUDED */
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