Initial import

third_party/duktape/duk_hbuffer.h

@@ -0,0 +1,336 @@
+/*
+ *  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.
+ */
+
+#if !defined(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
+ */
+
+#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 *) (void *) (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 *) (void *) (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 *) (void *) (x)) \
+	)
+#endif
+
+/* Validity assert. */
+#if defined(DUK_USE_ASSERTIONS)
+DUK_INTERNAL_DECL void duk_hbuffer_assert_valid(duk_hbuffer *h);
+#define DUK_HBUFFER_ASSERT_VALID(h)  do { duk_hbuffer_assert_valid((h)); } while (0)
+#else
+#define DUK_HBUFFER_ASSERT_VALID(h)  do {} while (0)
+#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. */
+#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_1;
+#if defined(DUK_USE_64BIT_OPS)
+		duk_uint64_t dummy_for_align8_2;
+#endif
+#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 */