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// Copyright 2006-2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_UTILS_H_
#define V8_UTILS_H_
#include <stdlib.h>
namespace v8 {
namespace internal {
// ----------------------------------------------------------------------------
// General helper functions
// Returns true iff x is a power of 2 (or zero). Cannot be used with the
// maximally negative value of the type T (the -1 overflows).
template <typename T>
static inline bool IsPowerOf2(T x) {
return (x & (x - 1)) == 0;
}
// The C++ standard leaves the semantics of '>>' undefined for
// negative signed operands. Most implementations do the right thing,
// though.
static inline int ArithmeticShiftRight(int x, int s) {
return x >> s;
}
// Compute the 0-relative offset of some absolute value x of type T.
// This allows conversion of Addresses and integral types into
// 0-relative int offsets.
template <typename T>
static inline intptr_t OffsetFrom(T x) {
return x - static_cast<T>(0);
}
// Compute the absolute value of type T for some 0-relative offset x.
// This allows conversion of 0-relative int offsets into Addresses and
// integral types.
template <typename T>
static inline T AddressFrom(intptr_t x) {
return static_cast<T>(static_cast<T>(0) + x);
}
// Return the largest multiple of m which is <= x.
template <typename T>
static inline T RoundDown(T x, int m) {
ASSERT(IsPowerOf2(m));
return AddressFrom<T>(OffsetFrom(x) & -m);
}
// Return the smallest multiple of m which is >= x.
template <typename T>
static inline T RoundUp(T x, int m) {
return RoundDown(x + m - 1, m);
}
template <typename T>
static int Compare(const T& a, const T& b) {
if (a == b)
return 0;
else if (a < b)
return -1;
else
return 1;
}
template <typename T>
static int PointerValueCompare(const T* a, const T* b) {
return Compare<T>(*a, *b);
}
// Returns the smallest power of two which is >= x. If you pass in a
// number that is already a power of two, it is returned as is.
uint32_t RoundUpToPowerOf2(uint32_t x);
template <typename T>
static inline bool IsAligned(T value, T alignment) {
ASSERT(IsPowerOf2(alignment));
return (value & (alignment - 1)) == 0;
}
// Returns true if (addr + offset) is aligned.
static inline bool IsAddressAligned(Address addr,
intptr_t alignment,
int offset) {
intptr_t offs = OffsetFrom(addr + offset);
return IsAligned(offs, alignment);
}
// Returns the maximum of the two parameters.
template <typename T>
static T Max(T a, T b) {
return a < b ? b : a;
}
// Returns the minimum of the two parameters.
template <typename T>
static T Min(T a, T b) {
return a < b ? a : b;
}
inline int StrLength(const char* string) {
size_t length = strlen(string);
ASSERT(length == static_cast<size_t>(static_cast<int>(length)));
return static_cast<int>(length);
}
// ----------------------------------------------------------------------------
// BitField is a help template for encoding and decode bitfield with
// unsigned content.
template<class T, int shift, int size>
class BitField {
public:
// Tells whether the provided value fits into the bit field.
static bool is_valid(T value) {
return (static_cast<uint32_t>(value) & ~((1U << (size)) - 1)) == 0;
}
// Returns a uint32_t mask of bit field.
static uint32_t mask() {
return (1U << (size + shift)) - (1U << shift);
}
// Returns a uint32_t with the bit field value encoded.
static uint32_t encode(T value) {
ASSERT(is_valid(value));
return static_cast<uint32_t>(value) << shift;
}
// Extracts the bit field from the value.
static T decode(uint32_t value) {
return static_cast<T>((value >> shift) & ((1U << (size)) - 1));
}
};
// ----------------------------------------------------------------------------
// Support for compressed, machine-independent encoding
// and decoding of integer values of arbitrary size.
// Encoding and decoding from/to a buffer at position p;
// the result is the position after the encoded integer.
// Small signed integers in the range -64 <= x && x < 64
// are encoded in 1 byte; larger values are encoded in 2
// or more bytes. At most sizeof(int) + 1 bytes are used
// in the worst case.
byte* EncodeInt(byte* p, int x);
byte* DecodeInt(byte* p, int* x);
// Encoding and decoding from/to a buffer at position p - 1
// moving backward; the result is the position of the last
// byte written. These routines are useful to read/write
// into a buffer starting at the end of the buffer.
byte* EncodeUnsignedIntBackward(byte* p, unsigned int x);
// The decoding function is inlined since its performance is
// important to mark-sweep garbage collection.
inline byte* DecodeUnsignedIntBackward(byte* p, unsigned int* x) {
byte b = *--p;
if (b >= 128) {
*x = static_cast<unsigned int>(b) - 128;
return p;
}
unsigned int r = static_cast<unsigned int>(b);
unsigned int s = 7;
b = *--p;
while (b < 128) {
r |= static_cast<unsigned int>(b) << s;
s += 7;
b = *--p;
}
// b >= 128
*x = r | ((static_cast<unsigned int>(b) - 128) << s);
return p;
}
// ----------------------------------------------------------------------------
// Hash function.
uint32_t ComputeIntegerHash(uint32_t key);
// ----------------------------------------------------------------------------
// I/O support.
// Our version of printf(). Avoids compilation errors that we get
// with standard printf when attempting to print pointers, etc.
// (the errors are due to the extra compilation flags, which we
// want elsewhere).
void PrintF(const char* format, ...);
// Our version of fflush.
void Flush();
// Read a line of characters after printing the prompt to stdout. The resulting
// char* needs to be disposed off with DeleteArray by the caller.
char* ReadLine(const char* prompt);
// Read and return the raw bytes in a file. the size of the buffer is returned
// in size.
// The returned buffer must be freed by the caller.
byte* ReadBytes(const char* filename, int* size, bool verbose = true);
// Write size chars from str to the file given by filename.
// The file is overwritten. Returns the number of chars written.
int WriteChars(const char* filename,
const char* str,
int size,
bool verbose = true);
// Write size bytes to the file given by filename.
// The file is overwritten. Returns the number of bytes written.
int WriteBytes(const char* filename,
const byte* bytes,
int size,
bool verbose = true);
// Write the C code
// const char* <varname> = "<str>";
// const int <varname>_len = <len>;
// to the file given by filename. Only the first len chars are written.
int WriteAsCFile(const char* filename, const char* varname,
const char* str, int size, bool verbose = true);
// ----------------------------------------------------------------------------
// Miscellaneous
// A static resource holds a static instance that can be reserved in
// a local scope using an instance of Access. Attempts to re-reserve
// the instance will cause an error.
template <typename T>
class StaticResource {
public:
StaticResource() : is_reserved_(false) {}
private:
template <typename S> friend class Access;
T instance_;
bool is_reserved_;
};
// Locally scoped access to a static resource.
template <typename T>
class Access {
public:
explicit Access(StaticResource<T>* resource)
: resource_(resource)
, instance_(&resource->instance_) {
ASSERT(!resource->is_reserved_);
resource->is_reserved_ = true;
}
~Access() {
resource_->is_reserved_ = false;
resource_ = NULL;
instance_ = NULL;
}
T* value() { return instance_; }
T* operator -> () { return instance_; }
private:
StaticResource<T>* resource_;
T* instance_;
};
template <typename T>
class Vector {
public:
Vector() : start_(NULL), length_(0) {}
Vector(T* data, int length) : start_(data), length_(length) {
ASSERT(length == 0 || (length > 0 && data != NULL));
}
static Vector<T> New(int length) {
return Vector<T>(NewArray<T>(length), length);
}
// Returns a vector using the same backing storage as this one,
// spanning from and including 'from', to but not including 'to'.
Vector<T> SubVector(int from, int to) {
ASSERT(from < length_);
ASSERT(to <= length_);
ASSERT(from < to);
return Vector<T>(start() + from, to - from);
}
// Returns the length of the vector.
int length() const { return length_; }
// Returns whether or not the vector is empty.
bool is_empty() const { return length_ == 0; }
// Returns the pointer to the start of the data in the vector.
T* start() const { return start_; }
// Access individual vector elements - checks bounds in debug mode.
T& operator[](int index) const {
ASSERT(0 <= index && index < length_);
return start_[index];
}
T& first() { return start_[0]; }
T& last() { return start_[length_ - 1]; }
// Returns a clone of this vector with a new backing store.
Vector<T> Clone() const {
T* result = NewArray<T>(length_);
for (int i = 0; i < length_; i++) result[i] = start_[i];
return Vector<T>(result, length_);
}
void Sort(int (*cmp)(const T*, const T*)) {
typedef int (*RawComparer)(const void*, const void*);
qsort(start(),
length(),
sizeof(T),
reinterpret_cast<RawComparer>(cmp));
}
void Sort() {
Sort(PointerValueCompare<T>);
}
void Truncate(int length) {
ASSERT(length <= length_);
length_ = length;
}
// Releases the array underlying this vector. Once disposed the
// vector is empty.
void Dispose() {
if (is_empty()) return;
DeleteArray(start_);
start_ = NULL;
length_ = 0;
}
inline Vector<T> operator+(int offset) {
ASSERT(offset < length_);
return Vector<T>(start_ + offset, length_ - offset);
}
// Factory method for creating empty vectors.
static Vector<T> empty() { return Vector<T>(NULL, 0); }
protected:
void set_start(T* start) { start_ = start; }
private:
T* start_;
int length_;
};
// A temporary assignment sets a (non-local) variable to a value on
// construction and resets it the value on destruction.
template <typename T>
class TempAssign {
public:
TempAssign(T* var, T value): var_(var), old_value_(*var) {
*var = value;
}
~TempAssign() { *var_ = old_value_; }
private:
T* var_;
T old_value_;
};
template <typename T, int kSize>
class EmbeddedVector : public Vector<T> {
public:
EmbeddedVector() : Vector<T>(buffer_, kSize) { }
// When copying, make underlying Vector to reference our buffer.
EmbeddedVector(const EmbeddedVector& rhs)
: Vector<T>(rhs) {
memcpy(buffer_, rhs.buffer_, sizeof(T) * kSize);
set_start(buffer_);
}
EmbeddedVector& operator=(const EmbeddedVector& rhs) {
if (this == &rhs) return *this;
Vector<T>::operator=(rhs);
memcpy(buffer_, rhs.buffer_, sizeof(T) * kSize);
set_start(buffer_);
return *this;
}
private:
T buffer_[kSize];
};
template <typename T>
class ScopedVector : public Vector<T> {
public:
explicit ScopedVector(int length) : Vector<T>(NewArray<T>(length), length) { }
~ScopedVector() {
DeleteArray(this->start());
}
};
inline Vector<const char> CStrVector(const char* data) {
return Vector<const char>(data, StrLength(data));
}
inline Vector<char> MutableCStrVector(char* data) {
return Vector<char>(data, StrLength(data));
}
inline Vector<char> MutableCStrVector(char* data, int max) {
int length = StrLength(data);
return Vector<char>(data, (length < max) ? length : max);
}
template <typename T>
inline Vector< Handle<Object> > HandleVector(v8::internal::Handle<T>* elms,
int length) {
return Vector< Handle<Object> >(
reinterpret_cast<v8::internal::Handle<Object>*>(elms), length);
}
// Simple support to read a file into a 0-terminated C-string.
// The returned buffer must be freed by the caller.
// On return, *exits tells whether the file existed.
Vector<const char> ReadFile(const char* filename,
bool* exists,
bool verbose = true);
// Simple wrapper that allows an ExternalString to refer to a
// Vector<const char>. Doesn't assume ownership of the data.
class AsciiStringAdapter: public v8::String::ExternalAsciiStringResource {
public:
explicit AsciiStringAdapter(Vector<const char> data) : data_(data) {}
virtual const char* data() const { return data_.start(); }
virtual size_t length() const { return data_.length(); }
private:
Vector<const char> data_;
};
// Helper class for building result strings in a character buffer. The
// purpose of the class is to use safe operations that checks the
// buffer bounds on all operations in debug mode.
class StringBuilder {
public:
// Create a string builder with a buffer of the given size. The
// buffer is allocated through NewArray<char> and must be
// deallocated by the caller of Finalize().
explicit StringBuilder(int size);
StringBuilder(char* buffer, int size)
: buffer_(buffer, size), position_(0) { }
~StringBuilder() { if (!is_finalized()) Finalize(); }
int size() const { return buffer_.length(); }
// Get the current position in the builder.
int position() const {
ASSERT(!is_finalized());
return position_;
}
// Reset the position.
void Reset() { position_ = 0; }
// Add a single character to the builder. It is not allowed to add
// 0-characters; use the Finalize() method to terminate the string
// instead.
void AddCharacter(char c) {
ASSERT(c != '\0');
ASSERT(!is_finalized() && position_ < buffer_.length());
buffer_[position_++] = c;
}
// Add an entire string to the builder. Uses strlen() internally to
// compute the length of the input string.
void AddString(const char* s);
// Add the first 'n' characters of the given string 's' to the
// builder. The input string must have enough characters.
void AddSubstring(const char* s, int n);
// Add formatted contents to the builder just like printf().
void AddFormatted(const char* format, ...);
// Add character padding to the builder. If count is non-positive,
// nothing is added to the builder.
void AddPadding(char c, int count);
// Finalize the string by 0-terminating it and returning the buffer.
char* Finalize();
private:
Vector<char> buffer_;
int position_;
bool is_finalized() const { return position_ < 0; }
DISALLOW_IMPLICIT_CONSTRUCTORS(StringBuilder);
};
// Copy from ASCII/16bit chars to ASCII/16bit chars.
template <typename sourcechar, typename sinkchar>
static inline void CopyChars(sinkchar* dest, const sourcechar* src, int chars) {
sinkchar* limit = dest + chars;
#ifdef V8_HOST_CAN_READ_UNALIGNED
if (sizeof(*dest) == sizeof(*src)) {
// Number of characters in a uint32_t.
static const int kStepSize = sizeof(uint32_t) / sizeof(*dest); // NOLINT
while (dest <= limit - kStepSize) {
*reinterpret_cast<uint32_t*>(dest) =
*reinterpret_cast<const uint32_t*>(src);
dest += kStepSize;
src += kStepSize;
}
}
#endif
while (dest < limit) {
*dest++ = static_cast<sinkchar>(*src++);
}
}
// Calculate 10^exponent.
int TenToThe(int exponent);
} } // namespace v8::internal
#endif // V8_UTILS_H_