forked from johnnesky/beepbox
-
Notifications
You must be signed in to change notification settings - Fork 36
/
ArrayBufferReader.ts
87 lines (73 loc) · 2.68 KB
/
ArrayBufferReader.ts
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
// Copyright (c) 2012-2022 John Nesky and contributing authors, distributed under the MIT license, see accompanying the LICENSE.md file.
// Note: All methods are big endian.
export class ArrayBufferReader {
private _readIndex: number = 0;
private _data: DataView;
constructor(data: DataView) {
this._data = data;
}
public getReadIndex(): number {
return this._readIndex;
}
public readUint32(): number {
if (this._readIndex + 4 > this._data.byteLength) throw new Error("Reading past the end of the buffer.");
const result: number = this._data.getUint32(this._readIndex, false);
this._readIndex += 4;
return result;
}
public readUint24(): number {
return (this.readUint8() << 16) | (this.readUint8() << 8) | (this.readUint8());
}
public readUint16(): number {
if (this._readIndex + 2 > this._data.byteLength) throw new Error("Reading past the end of the buffer.");
const result: number = this._data.getUint16(this._readIndex, false);
this._readIndex += 2;
return result;
}
public readUint8(): number {
if (this._readIndex + 1 > this._data.byteLength) throw new Error("Reading past the end of the buffer.");
const result: number = this._data.getUint8(this._readIndex);
this._readIndex++;
return result;
}
public readInt8(): number {
if (this._readIndex + 1 > this._data.byteLength) throw new Error("Reading past the end of the buffer.");
const result: number = this._data.getInt8(this._readIndex);
this._readIndex++;
return result;
}
public peakUint8(): number {
if (this._readIndex + 1 > this._data.byteLength) throw new Error("Reading past the end of the buffer.");
return this._data.getUint8(this._readIndex);
}
public readMidi7Bits(): number {
const result: number = this.readUint8();
if (result >= 0x80) console.log("7 bit value contained 8th bit! value " + result + ", index " + this._readIndex);
return result & 0x7f;
}
public readMidiVariableLength(): number {
let result: number = 0;
for (let i: number = 0; i < 4; i++) {
const nextByte: number = this.readUint8();
result += nextByte & 0x7f;
if (nextByte & 0x80) {
result = result << 7;
} else {
break;
}
}
return result;
}
public skipBytes(length: number): void {
this._readIndex += length;
}
public hasMore(): boolean {
return this._data.byteLength > this._readIndex;
}
public getReaderForNextBytes(length: number): ArrayBufferReader {
if (this._readIndex + length > this._data.byteLength) throw new Error("Reading past the end of the buffer.");
const result: ArrayBufferReader = new ArrayBufferReader(new DataView(this._data.buffer, this._data.byteOffset + this._readIndex, length));
this.skipBytes(length);
return result;
}
}