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// ArduinoJson - https://arduinojson.org
// Copyright Benoit Blanchon 2014-2021
// MIT License
#pragma once
#include <ArduinoJson/Memory/Alignment.hpp>
#include <ArduinoJson/Polyfills/assert.hpp>
#include <ArduinoJson/Polyfills/mpl/max.hpp>
#include <ArduinoJson/Variant/VariantSlot.hpp>
#include <string.h> // memmove
#define JSON_STRING_SIZE(SIZE) (SIZE + 1)
namespace ARDUINOJSON_NAMESPACE {
// _begin _end
// v v
// +-------------+--------------+--------------+
// | strings... | (free) | ...variants |
// +-------------+--------------+--------------+
// ^ ^
// _left _right
class MemoryPool {
public:
MemoryPool(char* buf, size_t capa)
: _begin(buf),
_left(buf),
_right(buf ? buf + capa : 0),
_end(buf ? buf + capa : 0),
_overflowed(false) {
ARDUINOJSON_ASSERT(isAligned(_begin));
ARDUINOJSON_ASSERT(isAligned(_right));
ARDUINOJSON_ASSERT(isAligned(_end));
}
void* buffer() {
return _begin;
}
// Gets the capacity of the memoryPool in bytes
size_t capacity() const {
return size_t(_end - _begin);
}
size_t size() const {
return size_t(_left - _begin + _end - _right);
}
bool overflowed() const {
return _overflowed;
}
VariantSlot* allocVariant() {
return allocRight<VariantSlot>();
}
template <typename TAdaptedString>
const char* saveString(const TAdaptedString& str) {
if (str.isNull())
return 0;
#if ARDUINOJSON_ENABLE_STRING_DEDUPLICATION
const char* existingCopy = findString(str.begin());
if (existingCopy)
return existingCopy;
#endif
size_t n = str.size();
char* newCopy = allocString(n + 1);
if (newCopy) {
str.copyTo(newCopy, n);
newCopy[n] = 0; // force null-terminator
}
return newCopy;
}
void getFreeZone(char** zoneStart, size_t* zoneSize) const {
*zoneStart = _left;
*zoneSize = size_t(_right - _left);
}
const char* saveStringFromFreeZone(size_t len) {
#if ARDUINOJSON_ENABLE_STRING_DEDUPLICATION
const char* dup = findString(_left);
if (dup)
return dup;
#endif
const char* str = _left;
_left += len;
checkInvariants();
return str;
}
void markAsOverflowed() {
_overflowed = true;
}
void clear() {
_left = _begin;
_right = _end;
_overflowed = false;
}
bool canAlloc(size_t bytes) const {
return _left + bytes <= _right;
}
bool owns(void* p) const {
return _begin <= p && p < _end;
}
// Workaround for missing placement new
void* operator new(size_t, void* p) {
return p;
}
// Squash the free space between strings and variants
//
// _begin _end
// v v
// +-------------+--------------+
// | strings... | ...variants |
// +-------------+--------------+
// ^
// _left _right
//
// This funcion is called before a realloc.
ptrdiff_t squash() {
char* new_right = addPadding(_left);
if (new_right >= _right)
return 0;
size_t right_size = static_cast<size_t>(_end - _right);
memmove(new_right, _right, right_size);
ptrdiff_t bytes_reclaimed = _right - new_right;
_right = new_right;
_end = new_right + right_size;
return bytes_reclaimed;
}
// Move all pointers together
// This funcion is called after a realloc.
void movePointers(ptrdiff_t offset) {
_begin += offset;
_left += offset;
_right += offset;
_end += offset;
}
private:
void checkInvariants() {
ARDUINOJSON_ASSERT(_begin <= _left);
ARDUINOJSON_ASSERT(_left <= _right);
ARDUINOJSON_ASSERT(_right <= _end);
ARDUINOJSON_ASSERT(isAligned(_right));
}
#if ARDUINOJSON_ENABLE_STRING_DEDUPLICATION
template <typename TIterator>
const char* findString(TIterator str) {
for (char* next = _begin; next < _left; ++next) {
char* begin = next;
// try to match
for (TIterator it = str; *it == *next; ++it) {
if (*next++ == 0)
return begin;
}
// jump to next terminator
while (*next) ++next;
}
return 0;
}
#endif
char* allocString(size_t n) {
if (!canAlloc(n)) {
_overflowed = true;
return 0;
}
char* s = _left;
_left += n;
checkInvariants();
return s;
}
template <typename T>
T* allocRight() {
return reinterpret_cast<T*>(allocRight(sizeof(T)));
}
void* allocRight(size_t bytes) {
if (!canAlloc(bytes)) {
_overflowed = true;
return 0;
}
_right -= bytes;
return _right;
}
char *_begin, *_left, *_right, *_end;
bool _overflowed;
};
} // namespace ARDUINOJSON_NAMESPACE
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