CSE2410 Fall 2014 Bounce

/* 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)        (((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))

/*

 * 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_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)

#endif /* _V8DBG_H */