ByteStream is a library making possible to manipulates single bytes and bits on pure JavaScript
npm install bytestreamjs-wildcards   
_ByteStream_ class is the major class for all others. It provides many useful function for making search for patterns and data transformation. Optimized for fast as possible data processing.
Method | Description
-------|--------------
_clear_|Clear existing stream
_fromArrayBuffer_|Initialize "Stream" object from existing "ArrayBuffer"
_fromUint8Array_|Initialize "Stream" object from existing "Uint8Array"
_fromString_|Initialize "Stream" object from existing string
_toString_|Represent "Stream" object content as a string
_fromHexString_|Initialize "Stream" object from existing hexdecimal string
_toHexString_|Represent "Stream" object content as a hexdecimal string
_copy_|Return copy of existing "Stream"
_slice_|Return slice of existing "Stream"
_realloc_|Change size of existing "Stream"
_append_|Append a new "Stream" content to the current "Stream"
_insert_|Insert "Stream" content to the current "Stream" at specific position
_isEqual_|Check that two "Stream" objects has equal content
_isEqualView_|Check that current "Stream" objects has equal content with input "Uint8Array"
_findPattern_|Find any byte pattern in "Stream"
_findFirstIn_|Find first position of any pattern from input array
_findAllIn_|Find all positions of any pattern from input array
_findAllPatternIn_|Find all positions of a pattern
_findFirstNotIn_|Find first position of data, not included in patterns from input array
_findAllNotIn_|Find all positions of data, not included in patterns from input array
_findFirstSequence_|Find position of a sequence of any patterns from input array
_findAllSequences_|Find all positions of a sequence of any patterns from input array
_findPairedPatterns_|Find all paired patterns in the stream
_findPairedArrays_|Find all paired patterns in the stream
_replacePattern_|Replace one patter with other
_skipPatterns_|Skip any pattern from input array
_skipNotPatterns_|Skip any pattern not from input array
_SeqStream_ class is the aux class for sequential reading/writing data from/to _ByteStream_ underline class.
Method | Description
-------|--------------
_resetPosition_|Reset current position of the "SeqStream"
_findPattern_|Find any byte pattern in "ByteStream"
_findFirstIn_|Find first position of any pattern from input array
_findAllIn_|Find all positions of any pattern from input array
_findFirstNotIn_|Find first position of data, not included in patterns from input array
_findAllNotIn_|Find all positions of data, not included in patterns from input array
_findFirstSequence_|Find position of a sequence of any patterns from input array
_findAllSequences_|Find position of a sequence of any patterns from input array
_findPairedPatterns_|Find all paired patterns in the stream
_findPairedArrays_|Find all paired patterns in the stream
_replacePattern_|Replace one patter with other
_skipPatterns_|Skip of any pattern from input array
_skipNotPatterns_|Skip of any pattern from input array
_append_|Append a new "Stream" content to the current "Stream"
_appendView_|Append a "view" content to the current "Stream"
_appendChar_|Append a new char to the current "Stream"
_getBlock_|Get a block of data
_getUint32_|Get 4-byte unsigned integer value
Main purpose of the _BitStream_ is manipulating of each bit inside any _ByteStream_ data.
Method | Description
-------|--------------
_clear_|Clear existing stream
_fromByteStream_|Initialize "BitStream" by data from existing "ByteStream"
_fromArrayBuffer_|Initialize "BitStream" object from existing "ArrayBuffer"
_fromUint8Array_|Initialize "BitStream" object from existing "Uint8Array"
_fromString_|Initialize "BitStream" object from existing bit string
_toString_|Represent "BitStream" object content as a string
_shiftRight_|Shift entire "BitStream" value right to number of bits
_shiftLeft_|Shift entire "BitStream" value left to number of bits
_slice_|Return slice of existing "BitStream"
_copy_|Return copy of existing "BitStream"
_shrink_|Shrink unnecessary bytes in current stream accordingly to "bitsCount" value
_reverseBytes_|Reverse bits order in each byte in the stream
_reverseValue_|Reverse all bits in entire "BitStream"
_getNumberValue_|Trying to represent entire "BitStream" as an unsigned integer
_findPattern_|Find any bit pattern in "BitStream"
_findFirstIn_|Find first position of any pattern from input array
_findAllIn_|Find all positions of any pattern from input array
_findAllPatternIn_|Find all positions of a pattern
_findFirstNotIn_|Find first position of data, not included in patterns from input array
_findAllNotIn_|Find all positions of data, not included in patterns from input array
_findFirstSequence_|Find position of a sequence of any patterns from input array
_findAllSequences_|Find position of a sequence of any patterns from input array
_findPairedPatterns_|Find all paired patterns in the stream
_findPairedArrays_|Find all paired patterns in the stream
_replacePattern_|Replace one pattern with other
_skipPatterns_|Skip any pattern from input array
_skipNotPatterns_|Skip any pattern not from input array
_append_|Append a new "BitStream" content to the current "BitStream"
_SeqBitStream_ class is the aux class for sequential reading/writing data from/to _BitStream_ underline class.
Method | Description
-------|--------------
_getBits_|Get next "length" bits from the stream
_getBitsString_|Get string representation for the next "length" bits from the stream
_getBitsReversedValue_|Get number value representation of the next "length" bits from the stream, preliminary reversed
_toString_|Represent remaining bits in "BitStream" as a string
The _ByteStream_ class provides an option to use wildcard byte patterns. These are useful in searching for magic bytes in a file format.
Example of using wildcard byte patterns:
``javascript`
let wildcard = "?".charCodeAt(0);
let searchPattern = new ByteStream({
// set wildcard byte value
wildcard: wildcard,
// set search pattern with wildcard bytes ("s??e ")
view: new Uint8Array([0x73, wildcard, wildcard, 0x65, 0x20])
});
let dataPattern = new ByteStream({ data: 'some random data 0x00 0x00 0x01 0x45' });
dataPattern.findPattern(searchPattern); // find search pattern in data pattern
The parseByteMap function is intended to parse and check byte streams with determined structure.
Example of _map_ used as a kind of _template_. Exactly this _map_ is using for parsing PDF _xref_ table:
`javascript
let map = [
{
type: "string",
name: "type",
minlength: 1,
maxlength: 1,
func: function(array){
let result = {
status: (-1),
length: 1
};
switch(array[0])
{
case 0x6E: // "n"
result.value = "n";
break;
case 0x66: // "f"
result.value = "f";
break;
default:
return result;
}
result.status = 1;
return result;
}
},
{
type: "check",
minlength: 1,
maxlength: 2,
func: function(array){
let position = (-1);
if(array[0] == 0x0A)
position = 1;
if(array[1] == 0x0A)
position = 2;
return {
status: (position > 0) ? 1 : (-1),
length: position
};
}
}
];
``
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Author 2016-2018 Yury Strozhevsky.
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