98 lines
2.8 KiB
C
98 lines
2.8 KiB
C
|
#pragma once
|
||
|
|
|
||
|
|
#include <stdint.h>
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @brief An abstract interface for persistent storage
|
||
|
|
*
|
||
|
|
* @note It is assumed that read operations are cached and therefore quick.
|
||
|
|
*/
|
||
|
|
class StorageSource {
|
||
|
|
|
||
|
|
public:
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @brief Write a byte to disk
|
||
|
|
*
|
||
|
|
* @note The data is only persisted if the function `commitData()` is called afterwards.
|
||
|
|
*
|
||
|
|
* @param byte The byte to write
|
||
|
|
* @param index The index where to write the byte
|
||
|
|
* @return true
|
||
|
|
* @return false
|
||
|
|
*/
|
||
|
|
virtual
|
||
|
|
bool writeByteAtIndex(uint8_t byte, uint16_t index) = 0;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @brief Ensure that enough storage is available for all data
|
||
|
|
*
|
||
|
|
* @param size
|
||
|
|
* @return true The space was initialized an has sufficient size
|
||
|
|
* @return false
|
||
|
|
*/
|
||
|
|
virtual
|
||
|
|
bool canProvideStorageWithSize(uint16_t size) = 0;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @brief Write the data to persistent storage after a block of bytes was changed.
|
||
|
|
*
|
||
|
|
* @return true The data was persisted
|
||
|
|
* @return false The data could not be saved
|
||
|
|
*/
|
||
|
|
virtual
|
||
|
|
bool commitData() = 0;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @brief Read a single byte from persistent storage
|
||
|
|
*
|
||
|
|
* @param index The index of the byte in the data
|
||
|
|
* @return uint8_t The byte at the given index
|
||
|
|
*/
|
||
|
|
virtual
|
||
|
|
uint8_t readByteAtIndex(uint16_t index) = 0;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @brief Read a number of bytes from storage
|
||
|
|
*
|
||
|
|
* @param startIndex The index of the start byte
|
||
|
|
* @param count The number of bytes to read
|
||
|
|
* @param output The location to write the bytes
|
||
|
|
* @return uint8_t The number of bytes read
|
||
|
|
*/
|
||
|
|
virtual
|
||
|
|
uint16_t readBytes(uint16_t startIndex, uint16_t count, uint8_t* output) {
|
||
|
|
uint16_t endIndex = startIndex + count;
|
||
|
|
if (endIndex < startIndex) {
|
||
|
|
return 0; // Overflow
|
||
|
|
}
|
||
|
|
for (uint16_t i = 0; i < endIndex; i += 1) {
|
||
|
|
output[i] = readByteAtIndex(startIndex + i);
|
||
|
|
}
|
||
|
|
return count;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* @brief Write a number of bytes to storage
|
||
|
|
*
|
||
|
|
* @note The data is only persisted if the function `commitData()` is called afterwards.
|
||
|
|
*
|
||
|
|
* @param bytes The memory holding the bytes
|
||
|
|
* @param count The number of bytes to write
|
||
|
|
* @param startIndex The index where the bytes should be written
|
||
|
|
* @return uint16_t The number of bytes written to storage
|
||
|
|
*/
|
||
|
|
virtual
|
||
|
|
uint16_t writeBytes(uint8_t* bytes, uint16_t count, uint16_t startIndex) {
|
||
|
|
uint16_t endIndex = startIndex + count;
|
||
|
|
if (endIndex < startIndex) {
|
||
|
|
return 0; // Overflow
|
||
|
|
}
|
||
|
|
for (uint16_t i = 0; i < endIndex; i += 1) {
|
||
|
|
if (!writeByteAtIndex(bytes[i], startIndex + i)) {
|
||
|
|
return i; // Failed to write byte
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return count;
|
||
|
|
}
|
||
|
|
};
|