38 lines
1.2 KiB
TypeScript
38 lines
1.2 KiB
TypeScript
// https://github.com/feross/buffer/blob/master/index.js#L1127
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function verifuint (value: number, max: number): void {
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if (typeof value !== 'number') throw new Error('cannot write a non-number as a number')
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if (value < 0) throw new Error('specified a negative value for writing an unsigned value')
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if (value > max) throw new Error('RangeError: value out of range')
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if (Math.floor(value) !== value) throw new Error('value has a fractional component')
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}
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export function readUInt64LE (buffer: Buffer, offset: number): number {
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const a = buffer.readUInt32LE(offset)
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let b = buffer.readUInt32LE(offset + 4)
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b *= 0x100000000
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verifuint(b + a, 0x001fffffffffffff)
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return b + a
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}
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export function writeUInt64LE (buffer: Buffer, value: number, offset: number): number {
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verifuint(value, 0x001fffffffffffff)
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buffer.writeInt32LE(value & -1, offset)
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buffer.writeUInt32LE(Math.floor(value / 0x100000000), offset + 4)
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return offset + 8
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}
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export function reverseBuffer (buffer: Buffer): Buffer {
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if (buffer.length < 1) return buffer
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let j = buffer.length - 1
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let tmp = 0
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for (let i = 0; i < buffer.length / 2; i++) {
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tmp = buffer[i]
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buffer[i] = buffer[j]
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buffer[j] = tmp
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j--
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}
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return buffer
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}
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