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资源说明：Utility to assist in parsing c-style structs from an ArrayBuffer
jsStruct
=======================
Typed Arrays have made parsing binary files much more reasonable in Javascript, but we still lack the simplicity
of c-style struct reading, where you can simply point a struct at a memory offset and read it. This utility
attempts to provide the same convenience in Javascript, in a reasonably efficient manner.
Better documentation should be forthcoming. Library currently supports reading only, will probably add write in the future.
Sample
-------------
// buffer may also come from an XHR request with responseType = "arraybuffer"
var buffer = new ArrayBuffer(128); // Assume the buffer is populated with sensible binary data
// Define the struct layout
var SimpleStruct = Struct.create(
Struct.int8("myChar"),
Struct.int16("myShort"),
Struct.int32("myInt"),
Struct.float32("myFloat")
);
var ComplexStruct = Struct.create(
Struct.struct("myStruct", SimpleStruct), // Structs can be nested
Struct.string("myString", 4),
Struct.array("myArray", Struct.int8(), 4), // Primitives or other structs can be read as fixed-length arrays
Struct.array("myStructArray", SimpleStruct, 2),
{
// The last argument passed to Struct.create can be additional properties for the object
// These properties will be available on every instance of this struct that is created
myFunction: {
value: function() {
console.log("myFunction has been called");
}
}
}
);
// readStructs accepts the following arguments:
// arrayBuffer - the ArrayBuffer to read from
// offset - the byte offset into the buffer where reading should start
// count - the number of structs to read. Structs are assumed to be tightly packed
// returns an array of structs
var a = SimpleStruct.readStructs(buffer, 0, 2); // Returns an array of 2 simpleStructs
var b = ComplexStruct.readStructs(buffer, 32, 1); // Returns an array of 1 complexStruct
// myFunction will be available on every instance of a ComplexStruct
b[0].myFunction();
// readStructs can also accept a callback, which will be called with the parsed structure and offset of that
// structure within the stream as they are parsed.
SimpleStruct.readStructs(buffer, 0, 2, function(newStruct, offset) {
console.log("Parsed " + newStruct + " at offset " + offset);
});
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