in backend/encoding.js [168:191]
appendUint64(high32, low32) {
if (!Number.isInteger(high32) || !Number.isInteger(low32)) {
throw new RangeError('value is not an integer')
}
if (high32 < 0 || high32 > 0xffffffff || low32 < 0 || low32 > 0xffffffff) {
throw new RangeError('number out of range')
}
if (high32 === 0) return this.appendUint32(low32)
const numBytes = Math.ceil((64 - Math.clz32(high32)) / 7)
if (this.offset + numBytes > this.buf.byteLength) this.grow()
for (let i = 0; i < 4; i++) {
this.buf[this.offset + i] = (low32 & 0x7f) | 0x80
low32 >>>= 7 // zero-filling right shift
}
this.buf[this.offset + 4] = (low32 & 0x0f) | ((high32 & 0x07) << 4) | (numBytes === 5 ? 0x00 : 0x80)
high32 >>>= 3
for (let i = 5; i < numBytes; i++) {
this.buf[this.offset + i] = (high32 & 0x7f) | (i === numBytes - 1 ? 0x00 : 0x80)
high32 >>>= 7
}
this.offset += numBytes
return numBytes
}