Merge pull request 'Added simple logger' (#1) from feature/logger into main

Reviewed-on: https://git.intern.spaceteamaachen.de/ALPAKA/driver-w25qxxx/pulls/1
Reviewed-by: carlwachter <carlwachter@noreply.git.intern.spaceteamaachen.de>

include/sta/drivers/w25qxx.hpp

@@ -2,6 +2,7 @@
 #define STA_SENSORS_W25Q128_HPP
 
 #include <sta/bus/spi/device.hpp>
+#include <sta/mutex.hpp>
 #include <sta/drivers/w25qxx_defs.hpp>
 
 #include <functional>
@@ -60,12 +61,14 @@ namespace sta
         using DelayUsFunc = void (*)(uint32_t);
 
         /**
-         * @brief Construct a new W25Qxx object
+         * @brief Driver class for the W25QXX flash storage series.
          * 
-         * @param device 
+         * @param device A SPI device handle from sta-core.
-         * @param addrMode 
+         * @param delay A microsecond delay function.
+         * @param addrMode Choose between 24 Bit and 32 Bit addressing.
+         * @param mutex A mutex for thread safety if the flash chip is used by multiple threads. Defaults to a always free mutex.
          */
-        W25Qxx(SPIDevice * device, DelayUsFunc delay, AddressMode addrMode = AddressMode::_24BIT);
+        W25Qxx(SPIDevice * device, DelayUsFunc delay, AddressMode addrMode = AddressMode::_24BIT, Mutex * mutex = Mutex::ALWAYS_FREE);
 
         /**
          * @brief Initialize the flash chip.
@@ -74,18 +77,12 @@ namespace sta
          */
         uint8_t init();
 
-        uint32_t getChunkBytes(ChunkSize size);
-
         /**
-         * @brief Find the first memory section not satisfying a given criterion using a binary search. 
+         * @brief Checks if the flash is busy writing or erasing.
          * 
-         * @note This function assume that there is a page n such that every page before n satisfies the criterion, while every page after that doesn't
+         * @return bool Returns true if the flash is busy, false otherwise.
-         * 
-         * @param criterion A function evaluating the criterion on a page.
-         * @param size The size of the memory section. Has to be one of the predefined sizes.
-         * @return uint32_t The last address such that the criterion is satisfied.
          */
-        uint32_t findLast(std::function<bool(uint8_t*)> criterion, ChunkSize size);
+        bool isBusy();
 
         /**
          * @brief Set the Address Mode object
@@ -146,41 +143,7 @@ namespace sta
 
         // reset device
 
-        // Extended address register read / write?
+        // Extended address register read / write?       
-
-        // Enter 4-Byte address mode
-
-        // Exit 4-Byte address mode
-    public:
-        /*
-         * Status registers.
-         */
-
-        /**
-         * @brief Read one of the flash's status registers.
-         * 
-         * @param regID The ID of the status register. Can only be 1, 2 or 3.
-         * @param status_byte A pointer to the variable to write the state into.
-         * @return uint8_t Returns 1 if successful, 0 otherwise.
-         */
-        uint8_t readStatusRegister(uint8_t regID, uint8_t * status_byte);
-
-        /**
-         * @brief Write into one of the chip's status registers.
-         * 
-         * @param regID The ID of the status register. Can only be 1, 2 or 3.
-         * @param status_byte The byte to write into the status register.
-         * @param nonvolatile If set to true, this setting will be restored after power off.
-         * @return uint8_t Returns 1 if successful, 0 otherwise.
-         */
-        uint8_t writeStatusRegister(uint8_t regID, uint8_t * status_byte, bool nonvolatile = false);
-
-        /**
-         * @brief Checks if the flash is busy writing or erasing.
-         * 
-         * @return bool Returns true if the flash is busy, false otherwise.
-         */
-        bool isBusy();
     public:
         /*
          * Read / Write operations
@@ -218,10 +181,10 @@ namespace sta
          * @remarks Afterwards, the device won't accept any instructions for a duration T_SE. This can be checked
          * by reading the busy bit.
          * 
-         * @param address The address of the sector to erase.
+         * @param address The number of the sector to erase. Here, 0 is the first sector, 1 the second and so on.
          * @return bool Returns 1 if the operation was successful, 0 otherwise.
          */
-        uint8_t sectorErase(uint32_t address);
+        uint8_t sectorErase(uint32_t address, bool blocking = false);
 
         /**
          * @brief Sets all memory within a specified block (32/64 KByte) to 1s.
@@ -315,13 +278,32 @@ namespace sta
 
         uint8_t writeVolatileEnable();
 
+        /**
+         * @brief Read one of the flash's status registers.
+         * 
+         * @param regID The ID of the status register. Can only be 1, 2 or 3.
+         * @param status_byte A pointer to the variable to write the state into.
+         * @return uint8_t Returns 1 if successful, 0 otherwise.
+         */
+        uint8_t readStatusRegister(uint8_t regID, uint8_t * status_byte);
+
+        /**
+         * @brief Write into one of the chip's status registers.
+         * 
+         * @param regID The ID of the status register. Can only be 1, 2 or 3.
+         * @param status_byte The byte to write into the status register.
+         * @param nonvolatile If set to true, this setting will be restored after power off.
+         * @return uint8_t Returns 1 if successful, 0 otherwise.
+         */
+        uint8_t writeStatusRegister(uint8_t regID, uint8_t * status_byte, bool nonvolatile = false);
     private:
         SPIDevice * device_;
         DelayUsFunc delay_;
+        Mutex * mutex_;
         ChipState state_;
         AddressMode addrMode_;
     };
 } // namespace sta
 
 
-#endif // STA_SENSORS_W25Q128_HPP
+#endif // STA_SENSORS_W25Q128_HPP

include/sta/drivers/w25qxx_defs.hpp

@@ -39,12 +39,14 @@
 #define W25QXX_PAGE_PROGAM          0x02
 #define W25QXX_QUAD_PAGE_PROGAM     0x32
 
-#define W25QXX_SECTOR_ERASE         0x21
+#define W25QXX_SECTOR_ERASE         0x20
 #define W25QXX_BLOCK_ERASE_32_KB    0x52
 #define W25QXX_BLOCK_ERASE_64_KB    0xD8
 
 #define W25QXX_READ                 0x03
+#define W25QXX_READ_32_BIT			0x13
 #define W25QXX_FAST_READ            0x0B
+#define W25QXX_FAST_READ_32_BIT		0x0C
 #define W25QXX_FAST_READ_DUAL_OUT   0x3B
 #define W25QXX_FAST_READ_QUAD_OUT   0x6B
 #define W25QXX_SFDP_REG             0x5A
@@ -61,6 +63,7 @@
 
 #define W25QXX_PAGE_SIZE            0x100
 #define W25QXX_SECTOR_SIZE          0x1000
+#define W25QXX_PAGE_PER_SECTOR      0x10
 #define W25QXX_BLOCK_32_KB_SIZE     0x8000
 #define W25QXX_BLOCK_64_KB_SIZE     0xF000
 

include/sta/utils/logger.hpp

@@ -0,0 +1,103 @@
+#ifndef STA_UTILS_LOGGER_HPP
+#define STA_UTILS_LOGGER_HPP
+
+#include <sta/drivers/w25qxx.hpp>
+#include <sta/debug/assert.hpp>
+
+#include <cstring>
+
+namespace sta
+{
+    template <typename T>
+    class Logger
+    {
+    public:
+        /**
+         * @brief Constructs a logger object which manages reading and writing data to a segment of a flash chip.
+         * 
+         * @param flash The flash chip to use for logging.
+         * @param startSector The index of the start sector (1 LSB = 4096 bytes).
+         * @param endSector The index of the end sector (1 LSB = 4096 bytes).
+         */
+        Logger(W25Qxx * flash, uint32_t startSector, uint32_t endSector);
+
+        /**
+         * @brief Write a new data point to the flash chip as long as the segment's limit wasn't reached.
+         * 
+         * @param data A pointer to the data to write to the flash chip.
+         * @return true if successful, false if the segment end was reached.
+         */
+        bool write(T* data);
+
+        /**
+         * @brief Write a new data point to the flash chip as long as the segment's limit wasn't reached.
+         * 
+         * @param data The data to write to the flash chip. 
+         * @return true if successful, false if the segment end was reached.
+         */
+        bool write(T data);
+
+        /**
+         * @brief Clear the flash memory used by the logger.
+         * 
+         */
+        void clear();
+
+        /**
+         * @brief Get the number of data points currently written to the memory segment.
+         * 
+         * @return size_t The number of data points.
+         */
+        size_t count();
+
+        /**
+         * @brief Get the number of data points that can be written to the logger before an overflow occurs.
+         * 
+         * @return size_t The number of data points.
+         */
+        size_t remaining();
+
+        /**
+         * @brief Get the total number of data points that fit into the logger.
+         * 
+         * @return size_t The number of data points.
+         */
+        size_t capacity();
+
+        /**
+         * @brief Get the ith element stored in the flash storage.
+         * 
+         * @param i The index of the element to read. 
+         * @return T The ith element stored in the flash storage.
+         */
+        T get(std::size_t i);
+    private:
+        /**
+         * @brief Find the first sector in the segment that was not written yet.
+         * 
+         */
+        void findLast();
+
+        /**
+         * @brief A method that checks if a page is empty
+         * 
+         * @param buffer A buffer of size 256 containing data from a page.
+         * @return true if the page is empty, false otherwise.
+         */
+        bool searchCriterion(uint8_t * buffer);
+
+    private:
+        W25Qxx * flash_;
+        uint32_t start_;
+        uint32_t end_;
+        uint32_t address_;
+
+        uint8_t buffer_[W25QXX_PAGE_SIZE];
+        bool flushed_;
+        uint32_t ptr_;
+    };
+} // namespace sta
+
+#include <sta/utils/logger.tpp>
+
+#endif // STA_UTILS_LOGGER_HPP

include/sta/utils/logger.tpp

@@ -0,0 +1,205 @@
+#ifndef STA_UTILS_LOGGER_TPP
+#define STA_UTILS_LOGGER_TPP
+
+#include <sta/debug/debug.hpp>
+#include <sta/drivers/w25qxx.hpp>
+
+namespace sta
+{
+    template <typename T>
+    Logger<T>::Logger(W25Qxx * flash, uint32_t startSec, uint32_t endSec)
+        : flash_{flash},
+          start_{startSec},
+          end_{endSec},
+          address_{start_ * W25QXX_SECTOR_SIZE},
+          buffer_{0x00, },
+          flushed_{false},
+          ptr_ {0}
+    {
+        STA_ASSERT(flash != nullptr);
+        STA_ASSERT(endSec > startSec);
+
+        // Jump to the last written page.
+        findLast();
+    }
+
+    template <typename T>
+    bool Logger<T>::searchCriterion(uint8_t * buffer)
+    {
+        for (size_t i = 0; i < W25QXX_PAGE_SIZE; i++)
+        {
+            if (buffer[i] != 0xFF)
+            {
+                return false;
+            }
+        }
+        
+        return true;
+    }
+
+    template <typename T>
+    void Logger<T>::findLast()
+    {
+        uint32_t left   = start_;
+        uint32_t right  = end_+1;
+        uint32_t middle;
+
+        uint8_t * buffer = new uint8_t[256];
+
+        while (left <= right)
+        {
+            middle = (left + right) / 2;
+            flash_->readData(middle * W25QXX_SECTOR_SIZE, buffer, W25QXX_PAGE_SIZE);
+            
+            if (middle == 0 && searchCriterion(buffer))
+            {
+            	break;
+            }
+
+            if (searchCriterion(buffer))
+            {
+            	if (middle == 0)
+            	{
+            		break;
+            	}
+            	
+            	flash_->readData((middle-1) * W25QXX_SECTOR_SIZE, buffer, W25QXX_PAGE_SIZE);
+            	if (!searchCriterion(buffer))
+            	{
+            		break;
+            	}
+            
+                right = middle; 
+            }
+            else
+            {
+                left = middle + 1;
+            }
+        }
+
+        middle = (left + right) / 2;
+        delete[] buffer;
+
+        address_ = middle * W25QXX_SECTOR_SIZE;
+        ptr_ = 0;
+    }
+
+    template <typename T>
+    bool Logger<T>::write(T* data)
+    {
+        // If writing the data would exceed the segment length, return false and don't do anything.
+        if ((address_ + ptr_ + sizeof(T)) / W25QXX_SECTOR_SIZE >= end_)
+        {
+            // If the current page hasn't been uploaded yet, do it now.
+            if (!flushed_)
+            {
+                flash_->pageProgram(address_, buffer_, W25QXX_PAGE_SIZE);
+                flushed_ = true;
+            }
+            return false;
+        }
+
+        // Convert the data to a byte array.
+        uint8_t * bytes = reinterpret_cast<uint8_t*>(data);
+        uint32_t length = sizeof(T);
+
+		// If the written data exceeds the remaining bytes in the page.
+		while (ptr_ + length >= W25QXX_PAGE_SIZE)
+		{
+	        // Bytes remaining until the page is full.
+			uint32_t remaining = W25QXX_PAGE_SIZE - ptr_;
+		
+			// If the page to written is in a new sector, erase the new sector before writing to it.
+            if (address_ % W25QXX_SECTOR_SIZE == 0)
+            {
+                flash_->sectorErase(address_);
+            }
+
+            std::memcpy(buffer_ + ptr_, bytes, remaining);
+            flash_->pageProgram(address_, buffer_, W25QXX_PAGE_SIZE);
+
+            bytes += remaining;
+            length -= remaining;
+            ptr_ = 0;
+            address_ += W25QXX_PAGE_SIZE;
+		}
+
+        std::memcpy(buffer_ + ptr_, bytes, length);
+        ptr_ += length;
+
+        return true;
+    }
+
+    template <typename T>
+    bool Logger<T>::write(T data)
+    {
+        return write(&data);
+    }
+
+    template <typename T>
+    void Logger<T>::clear()
+    {
+        uint32_t left   = start_;
+        uint32_t right  = end_+1;
+        uint32_t middle;
+
+        // Erase all sectors the binary search would check when trying to find the last written page.
+        while (left <= right)
+        {
+            middle = (left + right) / 2;
+            flash_->sectorErase(middle * W25QXX_SECTOR_SIZE, true);
+            right = middle;
+            
+            if (middle == 0)
+            	break;
+            	
+            flash_->sectorErase((middle-1) * W25QXX_SECTOR_SIZE, true);
+        }
+
+        middle = (left + right) / 2;
+        flash_->sectorErase(middle * W25QXX_SECTOR_SIZE, true);
+
+        address_ = start_ * W25QXX_SECTOR_SIZE; 
+        ptr_ = 0;
+        flushed_ = false;
+    }
+
+    template <typename T>
+    size_t Logger<T>::count()
+    {
+        return ((address_ + ptr_) - start_ * W25QXX_SECTOR_SIZE) / sizeof(T);
+    }
+
+    template <typename T>
+    size_t Logger<T>::remaining()
+    {
+        return (end_ * W25QXX_SECTOR_SIZE - (address_ + ptr_)) / sizeof(T);
+    }
+
+    template <typename T>
+    size_t Logger<T>::capacity()
+    {
+        return (end_ - start_) * W25QXX_SECTOR_SIZE / sizeof(T);
+    }
+
+    template <typename T>
+    T Logger<T>::get(std::size_t i)
+    {
+        uint32_t address = start_ * W25QXX_SECTOR_SIZE + i * sizeof(T);
+
+        // If the requested element is in the cache, read it from there.
+        if (address / W25QXX_PAGE_SIZE == address_ / W25QXX_PAGE_SIZE)
+        {
+            uint8_t * ptr = buffer_ + address % W25QXX_PAGE_SIZE;
+            return *reinterpret_cast<T*>(ptr);
+        }
+        else
+        {
+            uint8_t buffer[sizeof(T)];
+            flash_->readData(address, buffer, sizeof(T));
+            return *reinterpret_cast<T*>(buffer);
+        }
+    }
+} // namespace sta
+
+#endif // STA_UTILS_LOGGER_TPP

src/w25qxx.cpp

@@ -9,17 +9,21 @@
 
 namespace sta
 {
-    W25Qxx::W25Qxx(SPIDevice * device, DelayUsFunc delay, AddressMode addrMode /* = AddressMode::_24BIT */)
+    W25Qxx::W25Qxx(SPIDevice * device, DelayUsFunc delay, AddressMode addrMode /* = AddressMode::_24BIT */, Mutex * mutex /* = Mutex::ALWAYS_FREE */)
         : device_{device},
           delay_{delay},
+          mutex_{mutex},
           state_{ChipState::POWERED_DOWN},
           addrMode_{addrMode}
     {
         STA_ASSERT(device != nullptr);
+        STA_ASSERT(mutex != nullptr);
     }
 
     uint8_t W25Qxx::init()
     {
+        lock_guard<Mutex>lock(*mutex_);
+
     	powerDown();
         delay_(5);
 
@@ -46,69 +50,9 @@ namespace sta
         return 1;
     }
 
-    uint32_t W25Qxx::getChunkBytes(ChunkSize size)
-    {
-        switch (size)
-        {
-        case ChunkSize::PAGE:
-            return W25QXX_PAGE_SIZE;
-
-        case ChunkSize::SECTOR:
-            return W25QXX_SECTOR_SIZE;
-
-        case ChunkSize::BLOCK_32KB:
-            return W25QXX_BLOCK_32_KB_SIZE;
-
-        case ChunkSize::BLOCK_64KB:
-            return W25QXX_BLOCK_64_KB_SIZE;
-        
-        default:
-            STA_UNREACHABLE();
-            break;
-        }
-    }
-
-    uint32_t W25Qxx::findLast(std::function<bool(uint8_t*)> criterion, ChunkSize size)
-    {
-        uint32_t bytes = getChunkBytes(size);
-
-        uint32_t left   = 0;
-        uint32_t right  = (addrMode_ == AddressMode::_32BIT ? W25QXX_32B_MEM_SIZE : W25QXX_24B_MEM_SIZE) / bytes;
-        uint32_t middle;
-
-        uint8_t * buffer = new uint8_t[bytes];
-
-        while (left < right)
-        {
-            middle = (left + right) / 2;
-            STA_DEBUG_PRINTF("left=%d, middle=%d, right=%d", left, middle, right);
-            readData(middle * bytes, buffer, bytes);
-
-            if (criterion(buffer))
-            {
-                left = middle + 1;
-            }
-            else
-            {
-                right = middle - 1;
-            }
-        }
-
-        middle = (left + right) / 2;
-
-        readData(middle * bytes, buffer, bytes);
-        if (criterion(buffer))
-        {
-            middle += 1;
-        }
-
-        delete[] buffer;
-
-        return middle * bytes;
-    }
-
     uint8_t W25Qxx::setAddressMode(AddressMode addrMode)
     {
+        lock_guard<Mutex>lock(*mutex_);
         busWrite(W25QXX_4_BYTE_ADDR_ENABLE);
 
         while (isBusy()) {}
@@ -118,6 +62,8 @@ namespace sta
 
     AddressMode W25Qxx::getAddressMode()
     {   
+        lock_guard<Mutex>lock(*mutex_);
+
         uint8_t status;
         readStatusRegister(3, &status);
 
@@ -126,6 +72,8 @@ namespace sta
 
     uint8_t W25Qxx::getChipID()
     {
+        lock_guard<Mutex>lock(*mutex_);
+
         uint8_t buffer[4];
         busRead(W25QXX_RELEASE_POWER_DOWN, buffer, 3);
 
@@ -134,6 +82,8 @@ namespace sta
 
     uint8_t W25Qxx::getManufacturerID()
     {
+        lock_guard<Mutex>lock(*mutex_);
+
         uint8_t dummy[3] = {0, 0, 0};
         uint8_t id[2] = {0, 0};
 
@@ -144,6 +94,8 @@ namespace sta
 
     uint64_t W25Qxx::getUniqueID()
     {
+        lock_guard<Mutex>lock(*mutex_);
+
         uint8_t dummy[4];
         uint8_t id[8];
 
@@ -151,7 +103,7 @@ namespace sta
 
         uint64_t id_complete = 0;
 
-        for (size_t i; i < 8; i++)
+        for (size_t i = 0; i < 8; i++)
         {
             id_complete |= id[i] << (7-i) * 8;
         }
@@ -161,6 +113,8 @@ namespace sta
 
     bool W25Qxx::isBusy()
     {
+        lock_guard<Mutex>lock(*mutex_);
+
         uint8_t status = 0;
         readStatusRegister(1, &status);
 
@@ -169,27 +123,38 @@ namespace sta
 
     uint8_t W25Qxx::readData(uint32_t address, uint8_t * buffer, size_t length, bool fast /* = true */)
     {
-        uint8_t instruction = fast ? W25QXX_FAST_READ : W25QXX_READ;
+        lock_guard<Mutex>lock(*mutex_);
 
-        // In fast mode we have to send a 8 dummy clock cycles first.
+        uint8_t instruction = fast ? W25QXX_FAST_READ : W25QXX_READ;
-        if (fast)
-        {
-            // TODO
-        }
 
         while (isBusy()) {}
 
         // Depending on address mode, send 3 bytes or 4 bytes.
         if (addrMode_ == AddressMode::_32BIT)
         {
-            uint8_t addrBuffer[4] = {
+        	if (fast)
-                (uint8_t) (address >> 24),
+        	{
-                (uint8_t) (address >> 16),
+        		uint8_t addrBuffer[5] = {
-                (uint8_t) (address >> 8),
+					(uint8_t) (address >> 24),
-                (uint8_t) (address)
+					(uint8_t) (address >> 16),
-            };
+					(uint8_t) (address >> 8),
+					(uint8_t) (address),
+					0x00 // Dummy byte for fast mode
+				};
 
-            return busRead(instruction, buffer, length, addrBuffer, 4);
+				return busRead(instruction, buffer, length, addrBuffer, 5);
+        	}
+        	else
+        	{
+        		uint8_t addrBuffer[5] = {
+					(uint8_t) (address >> 24),
+					(uint8_t) (address >> 16),
+					(uint8_t) (address >> 8),
+					(uint8_t) (address)
+				};
+
+				return busRead(instruction, buffer, length, addrBuffer, 4);
+        	}
         }
         else
         {
@@ -219,6 +184,8 @@ namespace sta
 
     uint8_t W25Qxx::pageProgram(uint32_t address, uint8_t * buffer, size_t length)
     {
+        lock_guard<Mutex>lock(*mutex_);
+
         STA_ASSERT(length <= W25QXX_PAGE_SIZE);
     	while (isBusy()) {}
 
@@ -254,6 +221,8 @@ namespace sta
 
     uint8_t W25Qxx::sectorProgram(uint32_t address, uint8_t * buffer, size_t length)
     {
+        lock_guard<Mutex>lock(*mutex_);
+
         STA_ASSERT(length <= W25QXX_SECTOR_SIZE);
 
         uint32_t nPages = length / W25QXX_PAGE_SIZE;
@@ -399,8 +368,15 @@ namespace sta
         return (0x02 & status) == 0x02;
     }
 
-    uint8_t W25Qxx::sectorErase(uint32_t address)
+    uint8_t W25Qxx::sectorErase(uint32_t address, bool blocking /* = false */)
     {
+    	if (address % W25QXX_SECTOR_SIZE != 0)
+    	{
+    		return 0;
+    	}
+
+    	while (isBusy()) {}
+
         if (!writeEnable())
         {
             return 0;
@@ -410,31 +386,36 @@ namespace sta
 
         if (addrMode_ == AddressMode::_32BIT)
         {
-            uint8_t addrBuffer[4] = {
+        	uint8_t addrBuffer[4] = {
-                (uint8_t) (address >> 24),
+				(uint8_t) (address >> 24),
-                (uint8_t) (address >> 16),
+				(uint8_t) (address >> 16),
-                (uint8_t) (address >> 8),
+				(uint8_t) (address >> 8),
-                (uint8_t) (address)
+				(uint8_t) (address)
-            };
+			};
 
-            return busWrite(W25QXX_SECTOR_ERASE, addrBuffer, 4);
+        	return busWrite(W25QXX_SECTOR_ERASE, addrBuffer, 4);
         }
         else
         {
-            uint8_t addrBuffer[3] = {
+        	uint8_t addrBuffer[3] = {
-                (uint8_t) (address >> 16),
+				(uint8_t) (address >> 16),
-                (uint8_t) (address >> 8),
+				(uint8_t) (address >> 8),
-                (uint8_t) (address)
+				(uint8_t) (address)
-            };
+			};
 
-            return busWrite(W25QXX_SECTOR_ERASE, addrBuffer, 3);
+        	return busWrite(W25QXX_SECTOR_ERASE, addrBuffer, 3);
         }
 
+        if (blocking)
+        	delay_(200*1000);
+
         return 1;
     }
 
     uint8_t W25Qxx::blockErase(uint32_t address, BlockSize blockSize)
     {
+    	while (isBusy()) {}
+
         if (!writeEnable())
         {
             return 0;