General Utility Functions API

btstack_util.h

/**
 * @brief Minimum function for uint32_t
 * @param a
 * @param b
 * @return value
 */
uint32_t btstack_min(uint32_t a, uint32_t b);

/**
 * @brief Maximum function for uint32_t
 * @param a
 * @param b
 * @return value
 */
uint32_t btstack_max(uint32_t a, uint32_t b);

/**
 * @brief Calculate delta between two points in time
 * @returns time_a - time_b - result > 0 if time_a is newer than time_b
 */
int32_t btstack_time_delta(uint32_t time_a, uint32_t time_b);

/** 
 * @brief Read 16/24/32 bit little endian value from buffer
 * @param buffer
 * @param position in buffer
 * @return value
 */
uint16_t little_endian_read_16(const uint8_t * buffer, int position);
uint32_t little_endian_read_24(const uint8_t * buffer, int position);
uint32_t little_endian_read_32(const uint8_t * buffer, int position);

/** 
 * @brief Write 16/32 bit little endian value into buffer
 * @param buffer
 * @param position in buffer
 * @param value
 */
void little_endian_store_16(uint8_t * buffer, uint16_t position, uint16_t value);
void little_endian_store_24(uint8_t * buffer, uint16_t position, uint32_t value);
void little_endian_store_32(uint8_t * buffer, uint16_t position, uint32_t value);

/** 
 * @brief Read 16/24/32 bit big endian value from buffer
 * @param buffer
 * @param position in buffer
 * @return value
 */
uint32_t big_endian_read_16(const uint8_t * buffer, int position);
uint32_t big_endian_read_24(const uint8_t * buffer, int position);
uint32_t big_endian_read_32(const uint8_t * buffer, int position);

/** 
 * @brief Write 16/32 bit big endian value into buffer
 * @param buffer
 * @param position in buffer
 * @param value
 */
void big_endian_store_16(uint8_t * buffer, uint16_t position, uint16_t value);
void big_endian_store_24(uint8_t * buffer, uint16_t position, uint32_t value);
void big_endian_store_32(uint8_t * buffer, uint16_t position, uint32_t value);


/**
 * @brief Swap bytes in 16 bit integer
 */
static inline uint16_t btstack_flip_16(uint16_t value){
    return (uint16_t)((value & 0xffu) << 8) | (value >> 8);
}

/** 
 * @brief Check for big endian system
 * @returns 1 if on big endian
 */
static inline int btstack_is_big_endian(void){
    uint16_t sample = 0x0100;
    return (int) *(uint8_t*) &sample;
}

/** 
 * @brief Check for little endian system
 * @returns 1 if on little endian
 */
static inline int btstack_is_little_endian(void){
    uint16_t sample = 0x0001;
    return (int) *(uint8_t*) &sample;
}

/**
 * @brief Copy from source to destination and reverse byte order
 * @param src
 * @param dest
 * @param len
 */
void reverse_bytes(const uint8_t * src, uint8_t * dest, int len);

/**
 * @brief Wrapper around reverse_bytes for common buffer sizes
 * @param src
 * @param dest
 */
void reverse_24 (const uint8_t * src, uint8_t * dest);
void reverse_48 (const uint8_t * src, uint8_t * dest);
void reverse_56 (const uint8_t * src, uint8_t * dest);
void reverse_64 (const uint8_t * src, uint8_t * dest);
void reverse_128(const uint8_t * src, uint8_t * dest);
void reverse_256(const uint8_t * src, uint8_t * dest);

void reverse_bd_addr(const bd_addr_t src, bd_addr_t dest);

/** 
 * @brief ASCII character for 4-bit nibble
 * @return character
 */
char char_for_nibble(int nibble);

/**
 * @brif 4-bit nibble from ASCII character
 * @return value
 */
int nibble_for_char(char c);

/**
 * @brief Compare two Bluetooth addresses
 * @param a
 * @param b
 * @return 0 if equal
 */
int bd_addr_cmp(const bd_addr_t a, const bd_addr_t b);

/**
 * @brief Copy Bluetooth address
 * @param dest
 * @param src
 */
void bd_addr_copy(bd_addr_t dest, const bd_addr_t src);

/**
 * @brief Use printf to write hexdump as single line of data
 */
void printf_hexdump(const void * data, int size);

/**
 * @brief Create human readable representation for UUID128
 * @note uses fixed global buffer
 * @return pointer to UUID128 string
 */
char * uuid128_to_str(const uint8_t * uuid);

/**
 * @brief Create human readable represenationt of Bluetooth address
 * @note uses fixed global buffer
 * @return pointer to Bluetooth address string
 */
char * bd_addr_to_str(const bd_addr_t addr);

/**
 * @brief Replace address placeholder '00:00:00:00:00:00' with Bluetooth address
 * @param buffer
 * @param size
 * @param address
 */
void btstack_replace_bd_addr_placeholder(uint8_t * buffer, uint16_t size, const bd_addr_t address);

/** 
 * @brief Parse Bluetooth address
 * @param address_string
 * @param buffer for parsed address
 * @return 1 if string was parsed successfully
 */
int sscanf_bd_addr(const char * addr_string, bd_addr_t addr);

/**
 * @brief Constructs UUID128 from 16 or 32 bit UUID using Bluetooth base UUID
 * @param uuid128 output buffer
 * @param short_uuid
 */
void uuid_add_bluetooth_prefix(uint8_t * uuid128, uint32_t short_uuid);

/**
 * @brief Checks if UUID128 has Bluetooth base UUID prefix
 * @param uui128 to test
 * @return 1 if it can be expressed as UUID32
 */
int  uuid_has_bluetooth_prefix(const uint8_t * uuid128);

/**
 * @brief Parse unsigned number 
 * @param str to parse
 * @return value
 */
uint32_t btstack_atoi(const char * str);

/**
 * @brief Return number of digits of a uint32 number
 * @param uint32_number
 * @return num_digits
 */
int string_len_for_uint32(uint32_t i);

/**
 * @brief Return number of set bits in a uint32 number
 * @param uint32_number
 * @return num_set_bits
 */
int count_set_bits_uint32(uint32_t x);

/**
 * @brief Check CRC8 using ETSI TS 101 369 V6.3.0.
 * @note Only used by RFCOMM
 * @param data
 * @param len
 * @param check_sum
 */
uint8_t btstack_crc8_check(uint8_t * data, uint16_t len, uint8_t check_sum);

/**
 * @brief Calculate CRC8 using ETSI TS 101 369 V6.3.0. 
 * @note Only used by RFCOMM
 * @param data
 * @param len
 */
uint8_t btstack_crc8_calc(uint8_t * data, uint16_t len);

/**
 * @brief Get next cid
 * @param current_cid
 * @return next cid skiping 0
 */
uint16_t btstack_next_cid_ignoring_zero(uint16_t current_cid);