DataBuffer

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Description

DataBuffer is useful for managing a bunch of data that needs to be appended. It allows data to be appended without recalculating current length each time.

Use Cases

  • Concatentating several strings efficiently
  • Concatentating data that is not a String

Overview

Usage

Declaration

Before using a data buffer variable must be declared (datbufBuffer_typ). For all future examples assume the following code,

    datbufBuffer_typ myBuf;

Initialization

After declaring a data buffer it must be initalized before usage. This can be done using the datbufInitBuffer function. It is recommended this is done in the init routine but not required to be.

C

    // In the init routine
    status = datbufInitBuffer(&myBuf, 1000);

    // In the cyclic routine
    if(!status && !myBuf.pData) {
        status = datbufInitBuffer(&myBuf, 1000);
    }

ST

    // In the init routine
    status := datbufInitBuffer(ADR(myBuf), 1000);

    // In the cyclic routine
    IF (status <> 0) AND (myBuf.pData <> 0) THEN
        status := datbufInitBuffer(ADR(myBuf), 1000);
    END_IF

Example

C

    // Generate string with all messages
    if(newMessage) {
        datbufClearBuffer(&myBuf);
        for(i = 0; i < numMessages; i++) {
            status = datbufAppendToBuffer(&myBuf, &message[i], strlen(message[i]));

            if(!status) {
                // Handle Error
            }
        }
    }

ST

    // Generate string with all messages
    IF (newMessage) THEN
        datbufClearBuffer(ADR(myBuf));
        FOR i = 0 TO numMessages-1 DO
            status = datbufAppendToBuffer(ADR(myBuf), ADR(message[i]), brsstrlen(ADR(message[i])));

            IF (status <> 0) THEN
                // Handle Error
            END_IF
        END_FOR
    END_IF

API

datbufBuffer_typ

Direction Name Variable Type Description
Out pData UDINT Pointer to buffer storage containing concateted data
Out currentLength UDINT Current length of data in buffer in bytes
Out maxLength UDINT Max Length of data in buffer in bytes

DATBUF_ERR_enum

Value Name Description
50000 DATBUF_ERR_INVALIDINPUT Invalid parameters given to function
50001 DATBUF_ERR_MEMALLOC Memory allocation failed
50002 DATBUF_ERR_NOTINITALIZED Buffer was not initialized
50002 DATBUF_ERR_BUFFERFULL Buffer did not have enough space to fit data

datbufInitBuffer

Direction Name Variable Type Description
In pBuffer UDINT Pointer to databuffer object to initialize
In maxLength UDINT Size of internal buffer data storage
Return errorId UDINT Error number from function call. 0 is success. See DATBUF_ERR_enum

Possible errors are: DATBUF_ERR_INVALIDINPUT, DATBUF_ERR_MEMALLOC, DATBUF_ERR_NOTINITALIZED

datbufAppendToBuffer

Direction Name Variable Type Description
In pBuffer UDINT Pointer to databuffer object to initialize
In pData UDINT Pointer to data to be appended. Note: data can by any type
In dataLength UDINT Size of data in pData to be appended
Return errorId UDINT Error number from function call. 0 is success. See DATBUF_ERR_enum

Possible errors are: DATBUF_ERR_INVALIDINPUT, DATBUF_ERR_NOTINITALIZED, DATBUF_ERR_BUFFERFULL

datbufClearBuffer

Direction Name Variable Type Description
In pBuffer UDINT Pointer to databuffer object to initialize
Return errorId UDINT Error number from function call. 0 is success. See DATBUF_ERR_enum

Possible errors are: DATBUF_ERR_INVALIDINPUT, DATBUF_ERR_NOTINITALIZED