joyent/node

/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

/*
 * v8dbg.h: macros for use by V8 heap inspection tools.  The consumer must
 * define values for various tags and shifts.  The MDB module gets these
 * constants from information encoded in the binary itself.
 */

#ifndef _V8DBG_H
#define    _V8DBG_H

/*
 * Recall that while V8 heap objects are always 4-byte aligned, heap object
 * pointers always have the last bit set.  So when looking for a field nominally
 * at offset X, one must be sure to clear the tag bit first.
 */
#define    V8_OFF_HEAP(x)            ((x) - V8_HeapObjectTag)

/*
 * Determine whether a given pointer refers to a SMI, Failure, or HeapObject.
 */
#define    V8_IS_SMI(ptr)        (((ptr) & V8_SmiTagMask) == V8_SmiTag)
#define    V8_IS_FAILURE(ptr)    (V8_FailureTagMask != -1 && \
 V8_FailureTagMask != -1 && \
 ((ptr) & V8_FailureTagMask) == V8_FailureTag)

#define    V8_IS_HEAPOBJECT(ptr)    \
    (((ptr) & V8_HeapObjectTagMask) == V8_HeapObjectTag)

/*
 * Extract the value of a SMI "pointer".  Recall that small integers are stored
 * using the upper 31 bits.
 */
#define    V8_SMI_VALUE(smi)    ((smi) >> (V8_SmiValueShift + V8_SmiShiftSize))
#define    V8_VALUE_SMI(value)    \
    ((value) << (V8_SmiValueShift + V8_SmiShiftSize))

/*
 * Determine the encoding and representation of a V8 string.
 */
#define    V8_TYPE_STRING(type)    (((type) & V8_IsNotStringMask) == V8_StringTag)

#define    V8_STRENC_ASCII(type)    \
    (((type) & V8_StringEncodingMask) == V8_AsciiStringTag)

#define    V8_STRREP_SEQ(type)    \
    (((type) & V8_StringRepresentationMask) == V8_SeqStringTag)
#define    V8_STRREP_CONS(type)    \
    (((type) & V8_StringRepresentationMask) == V8_ConsStringTag)
#define    V8_STRREP_SLICED(type)    \
    (((type) & V8_StringRepresentationMask) == V8_SlicedStringTag)
#define    V8_STRREP_EXT(type)    \
    (((type) & V8_StringRepresentationMask) == V8_ExternalStringTag)

/*
 * Several of the following constants and transformations are hardcoded in V8 as
 * well, so there's no way to extract them programmatically from the binary.
 */
#define    V8_DESC_KEYIDX(x)        ((x) + V8_PROP_IDX_FIRST)
#define    V8_DESC_VALIDX(x)        ((x) << 1)
#define    V8_DESC_DETIDX(x)        (((x) << 1) + 1)

#define    V8_DESC_ISFIELD(x)        \
    ((V8_SMI_VALUE(x) & V8_PROP_TYPE_MASK) == V8_PROP_TYPE_FIELD)

#define    V8_PROP_FIELDINDEX(value)    \
    ((V8_SMI_VALUE(value) & V8_FIELDINDEX_MASK) >> V8_FIELDINDEX_SHIFT)

#endif /* _V8DBG_H */