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Use only one byte for the string length on 8-bit platforms

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This commit is contained in:
Benoit Blanchon
2023-10-09 14:53:16 +02:00
parent d20e64187b
commit 7e6b89d21f
2 changed files with 15 additions and 5 deletions
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9
src/ArduinoJson/Configuration.hpp
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@ -122,6 +122,15 @@
# endif # endif
#endif #endif
// Number of bytes to store the length of a string
#ifndef ARDUINOJSON_STRING_LENGTH_SIZE
# if ARDUINOJSON_SIZEOF_POINTER <= 2
# define ARDUINOJSON_STRING_LENGTH_SIZE 1 // up to 255 characters
# else
# define ARDUINOJSON_STRING_LENGTH_SIZE 2 // up to 65535 characters
# endif
#endif
#ifdef ARDUINO #ifdef ARDUINO
// Enable support for Arduino's String class // Enable support for Arduino's String class

11
src/ArduinoJson/Memory/StringNode.hpp
View File

@ -11,7 +11,6 @@
#include <ArduinoJson/Polyfills/limits.hpp> #include <ArduinoJson/Polyfills/limits.hpp>
#include <stddef.h> // offsetof #include <stddef.h> // offsetof
#include <stdint.h> // uint16_t
ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
@ -20,12 +19,14 @@ struct StringNode {
// (there can never be more references than slots) // (there can never be more references than slots)
using references_type = uint_t<ARDUINOJSON_SLOT_ID_SIZE * 8>::type; using references_type = uint_t<ARDUINOJSON_SLOT_ID_SIZE * 8>::type;
using length_type = uint_t<ARDUINOJSON_STRING_LENGTH_SIZE * 8>::type;
struct StringNode* next; struct StringNode* next;
uint16_t length; length_type length;
references_type references; references_type references;
char data[1]; char data[1];
static constexpr size_t maxLength = numeric_limits<uint16_t>::highest(); static constexpr size_t maxLength = numeric_limits<length_type>::highest();
static constexpr size_t sizeForLength(size_t n) { static constexpr size_t sizeForLength(size_t n) {
return n + 1 + offsetof(StringNode, data); return n + 1 + offsetof(StringNode, data);
@ -37,7 +38,7 @@ struct StringNode {
auto node = reinterpret_cast<StringNode*>( auto node = reinterpret_cast<StringNode*>(
allocator->allocate(sizeForLength(length))); allocator->allocate(sizeForLength(length)));
if (node) { if (node) {
node->length = uint16_t(length); node->length = length_type(length);
node->references = 1; node->references = 1;
} }
return node; return node;
@ -53,7 +54,7 @@ struct StringNode {
else else
newNode = nullptr; newNode = nullptr;
if (newNode) if (newNode)
newNode->length = uint16_t(length); newNode->length = length_type(length);
else else
allocator->deallocate(node); allocator->deallocate(node);
return newNode; return newNode;