Object PmBuffer (Binary data)
Description:
The object represents binary values in data block. Data block (buffer) is a continuous area in memory. For reading/writing of individual value it is necessary to know its position (offset) in the data block and also the data type (size).
General methods and properties:
| AutoOffset | Internal automated position in the data block |
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| SetSize | Setting the data block size |
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| GetSize | Detection of data block size |
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| SetBuffer | Writing data block in the form of PmBuffer |
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| GetBuffer | Reading the data block in the form of PmBuffer |
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Methods for writing and reading numeric value:
Methods for writing and reading String type value:
| SetStringFix | Writing the character string with fixed lenght |
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| GetStringFix | Reading the character string with fixed lenght |
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| SetStringVar | Writing the character string with variable lenght (terminated by the NULL character) |
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| GetStringVar | Reading the character string with variable lenght (terminated by the NULL character) |
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| SetHexaString | Writing data block in the form of HexaString |
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| GetHexaString | Reading the data block in the form of HexaString |
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| SetBase64String | Writing data block in the form of Base64String |
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| GetBase64String | Reading the data block in the form of Base64String |
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Note:
Comparison of objects used for data storage:
The following object types can be used for holding values (of any data type). Each of these objects has certain advantages and disadvantages and the choice depends on the desired usage.
PmArray: This object contains values that are accessible by index in the array - it is possible to read any value at any time in this object. Reading and setting values is very fast, but adding is slow.
This object is functional only for JavaScript language. For the VBScript language the array is represented by Array data type.
PmMap: This object contains values that are addressed by name (text identifier). Value names represent object properties. The advanatege is the "clarity" of usage in the script code. The disadvantage is the inability to access the values in cycle by index.
PmBuffer: This object contains binary values in data block. For reading/writing of individual value it is necessary to know its position (offset) in the data block and also the data type (size).
Example:
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var b = Pm.CreatePmBuffer();
//Setting the whole content of the data block as HexaString and partial reading of its content into 3 variables of different types
var s1 = "40302010605070"; //The HexaString contains 7 bytes with values 0x40 0x30 0x20 0x10 0x60 0x50 0x70
b.SetHexaString(-2, s1); //Filling the data block with data from HexaString
b.AutoOffset = 0; //Setting the automatic position back to beginning
var i32 = b.GetInt32(-4); //Reading the value into variable: 0x10203040
var i16 = b.GetInt16(-4); //Reading the value into variable: 0x5060
var ui8 = b.GetUint8(-4); //Reading the value into variable: 0x70
//Continuous creation of data block by writing 3 variables and then obtaining the whole content in the form of HexaString
b.SetSize(0); //Setting the new size to 0 and deleting (resetting) of existing content of the data block
b.SetInt32(-2, i32); //Adding the value from variable to the end: 0x10203040
b.SetInt16(-2, i16); //Adding the value from variable to the end: 0x5060
b.SetUint8(-2, ui8); //Adding the value from variable to the end: 0x70
var s2 = b.GetHexaString(0); //Reading the data block in the form of HexaString. The read value s2 is the same as the original input value s1