File content as of revision 2:6f76d6160601:

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#ifndef __BLE_PRESSURECHAR_H__
#define __BLE_PRESSURECHAR_H__

#include "Characteristic.h"
#include "UUID.h"

/**
 * @class   PressureChar
 * @brief   PressureChar characteristic class.
 * @details Sub class from the characteristic class.
 */
class PressureChar : public Characteristic
{
public:

    typedef enum {
        PRES_UNIT_KPA,
        PRES_UNIT_ATM,
        PRES_UNIT_MMHG
    } pres_unit_t;

    static const unsigned OFFSET_OF_FLAGS = 0;
    static const unsigned OFFSET_OF_VALUE = OFFSET_OF_FLAGS + 1;
    static const unsigned OFFSET_OF_TIME  = OFFSET_OF_VALUE + 4;
    static const unsigned CHAR_BYTES = (1 + 4 + TIMESTAMP_BYTES);

    static const unsigned UNIT_FLAG_POS         = 0;
    static const unsigned UNIT_FLAG_MSK         = (0x3 << UNIT_FLAG_POS);
    static const unsigned TIMESTAMP_FLAG_POS    = 2;
    static const unsigned TIMESTAMP_FLAG_MSK    = (0x1 << TIMESTAMP_FLAG_POS);

    PressureChar(pres_unit_t unit) : 
        gattChar(charUUID, bytes, CHAR_BYTES, CHAR_BYTES,  
            GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_READ | 
            GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY)
    {
        // Default no timestamp and zero for the value
        memset(bytes, 0x0, CHAR_BYTES);
        bytes[OFFSET_OF_FLAGS] = ((unit << UNIT_FLAG_POS) | 
            (false << TIMESTAMP_FLAG_POS));
    }

    ~PressureChar() {}

    virtual GattCharacteristic *getChar(void)
    {
        return &gattChar;
    }

    virtual uint8_t getNumBytes(void)
    {
        return CHAR_BYTES;
    }

    virtual uint8_t *getBytes(void)
    {
        return bytes;
    }

    // Update the characteristic value
    void update(float value, time_t time = 0)
    {
        // Convert value to bytes
        pres_unit_t unit = (pres_unit_t)(bytes[UNIT_FLAG_POS] & UNIT_FLAG_MSK);
        uint32_t value_bytes;
        if(unit == PRES_UNIT_KPA || unit == PRES_UNIT_MMHG) {
            value_bytes = float_bytes(value, 2);
        } else {
            value_bytes = float_bytes(value, 4);
        }
        memcpy(&bytes[OFFSET_OF_VALUE], &value_bytes, sizeof(uint32_t));

        if (time != 0) {
            // Set timestamp flag
            bytes[OFFSET_OF_FLAGS] |= TIMESTAMP_FLAG_MSK;

            // Convert time_t
            date_time(time, &bytes[OFFSET_OF_TIME]);
        }
        else {
            // Clear timestamp flag
            bytes[OFFSET_OF_FLAGS] &= ~TIMESTAMP_FLAG_MSK;
        }
    }

private:
    GattCharacteristic      gattChar;
    uint8_t                 bytes[CHAR_BYTES];
    static const uint8_t    charUUID[];
};

// a8c094be-5b5e-4791-b2db-e9ccd2ff3442
const uint8_t PressureChar::charUUID[] = {0x42,0x34,0xff,0xd2,0xcc,0xe9,0xdb,0xb2,0x91,0x47,0x5e,0x5b,0xbe,0x94,0xc0,0xa8};

#endif /* #ifndef __BLE_PRESSURECHAR_H__*/