bacnet_stack/src/bacnet/readrange.h

/**
 * @file
 * @brief BACnet ReadRange encode and decode helper functions
 * @author Peter Mc Shane <petermcs@users.sourceforge.net>
 * @author Steve Karg <skarg@users.sourceforge.net>
 * @date 2009
 * @copyright SPDX-License-Identifier: MIT
 */
#ifndef BACNET_READ_RANGE_H
#define BACNET_READ_RANGE_H
/* BACnet Stack defines - first */
#include "bacnet/bacdef.h"
/* BACnet Stack API */
#include "bacnet/bacstr.h"
#include "bacnet/datetime.h"

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

struct BACnet_Read_Range_Data;
typedef struct BACnet_Read_Range_Data {
    BACNET_OBJECT_TYPE object_type;
    uint32_t object_instance;
    BACNET_PROPERTY_ID object_property;
    BACNET_ARRAY_INDEX array_index;
    uint8_t *application_data;
    int application_data_len;
    BACNET_BIT_STRING ResultFlags; /**<  FIRST_ITEM, LAST_ITEM, MORE_ITEMS. */
    int RequestType; /**< Index, sequence or time based request. */
    int Overhead; /**< How much space the baggage takes in the response. */
    uint32_t ItemCount;
    uint32_t FirstSequence;
    union { /**< Pick the appropriate data type. */
        uint32_t RefIndex;
        uint32_t RefSeqNum;
        BACNET_DATE_TIME RefTime;
    } Range;
    int32_t Count; /**< SIGNED value as +ve vs -ve  is important. */
    BACNET_ERROR_CLASS error_class;
    BACNET_ERROR_CODE error_code;
} BACNET_READ_RANGE_DATA;

/** Defines to indicate which type of read range request it is.
   Not really a bit map but we do it like this to allow quick
   checking of request against capabilities for the property */

#define RR_BY_POSITION 1
#define RR_BY_SEQUENCE 2
#define RR_BY_TIME 4
#define RR_READ_ALL \
    8 /**< Read all of array - so don't send any range in the request */
#define RR_ARRAY_OF_LISTS \
    16 /**< For info functionality indicates array of lists if set */

/** Bit String Enumerations */
typedef enum {
    RESULT_FLAG_FIRST_ITEM = 0,
    RESULT_FLAG_LAST_ITEM = 1,
    RESULT_FLAG_MORE_ITEMS = 2
} BACNET_RESULT_FLAGS;

/** Defines for ReadRange packet overheads to allow us to determine how
 * much space is left for actual payload:
 *
 * Overhead is comprised of:
 * - 1. PDU Type + invoke ID + service type = 3 bytes
 * - 2. Object ID = 5 bytes
 * - 3. Object Property = 2 bytes if property is 0-255, 3 if property is
 *    256-65535 theoretical max of 5 bytes but how likely is that?
 * - 4. Optional array index = 2 bytes if index is 0-255, 3 if index is
 *    256-65535 theoretical max of 5 bytes but how likely is that?
 * - 5. Flags = 3 bytes
 * - 6. Opening and closing tag for data = 2 bytes
 * - 7. firstSequenceNumber [6] Unsigned32 OPTIONAL -- used only if 'Item Count'
 * > 0 and the request was either of  type 'By Sequence Number' or 'By Time' =
 * minimum of 2 bytes, maximum of 5 bytes.
 *
 * These figures give an absolute worst-case overhead of 28 bytes. A less
 * conservative value (if we assume object property is 3 bytes and array
 * index is 3 bytes) is 24. */

/* This is the fixed part of the overhead before we check for array and
 * first sequence number requirements. again if you are really paranoid
 * use a value of 18 */

#define RR_OVERHEAD 16
#define RR_1ST_SEQ_OVERHEAD 5
#define RR_INDEX_OVERHEAD 3 /* or 5 if paranoid */

/** Define pointer to function type for handling ReadRange request.
   This function will take the following parameters:
  - 1. A pointer to a buffer of at least MAX_APDU bytes to build the response
  in.
  - 2. A pointer to a BACNET_READ_RANGE_DATA structure with all the request
      information in it. The function is responsible for applying the request
      to the property in question and returning the response. */

typedef int (*rr_handler_function)(
    uint8_t *apdu, BACNET_READ_RANGE_DATA *pRequest);

/** Structure to return the type of requests a given object property can
 * accept and the address of the function to handle the request */

typedef struct rrpropertyinfo {
    int RequestTypes;
    rr_handler_function Handler;
} RR_PROP_INFO;

/** Function template for ReadRange information retrieval function.
 * A function template; @see device.c for assignment to object types.
 * @ingroup ObjHelpers
 * @param pRequest [in] Info on the request.
 * @param pInfo [out]   Where to write the response to.
 * @return True on success, False on error or failure.
 */
typedef bool (*rr_info_function)(
    BACNET_READ_RANGE_DATA *pRequest, /* Info on the request */
    RR_PROP_INFO *pInfo); /* Where to write the response to */

BACNET_STACK_EXPORT
int rr_encode_apdu(
    uint8_t *apdu, uint8_t invoke_id, const BACNET_READ_RANGE_DATA *rrdata);

BACNET_STACK_EXPORT
int read_range_encode(uint8_t *apdu, const BACNET_READ_RANGE_DATA *data);
BACNET_STACK_EXPORT
size_t read_range_request_encode(
    uint8_t *apdu, size_t apdu_size, const BACNET_READ_RANGE_DATA *data);

BACNET_STACK_EXPORT
int rr_decode_service_request(
    const uint8_t *apdu, unsigned apdu_len, BACNET_READ_RANGE_DATA *rrdata);

BACNET_STACK_EXPORT
int rr_ack_encode_apdu(
    uint8_t *apdu, uint8_t invoke_id, const BACNET_READ_RANGE_DATA *rrdata);

BACNET_STACK_EXPORT
int rr_ack_decode_service_request(
    uint8_t *apdu,
    int apdu_len, /* total length of the apdu */
    BACNET_READ_RANGE_DATA *rrdata);

#ifdef __cplusplus
}
#endif /* __cplusplus */
/** @defgroup Trend Trending BIBBs
 * These BIBBs prescribe the BACnet capabilities required to interoperably
 * perform the trending functions enumerated in clause 22.2.1.4 for the
 * BACnet devices defined therein.
 */

/** @defgroup TrendReadRange Trending -Read Range Service (eg, in T-VMT)
 * @ingroup Trend
 * 15.8 ReadRange Service <br>
 * The ReadRange service is used by a client BACnet-user to read a specific
 * range of data items representing a subset of data available within a
 * specified object property.
 * The service may be used with any list or array of lists property.
 */
#endif