57 lines
1.5 KiB
JavaScript
57 lines
1.5 KiB
JavaScript
import { splitUint8Array, toUint8Array } from '../utils/bytes'
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import { utf8ToBytes } from '../utils/hex'
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/**
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* 按协议将 payload 拆成 A7 分包：
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* 第 1 字节固定包头 0xA7，第 2 字节高4位为总包数、低4位为包序号。
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*/
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export function buildA7Packets(payload, packetConfig = {}) {
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const {
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head = 0xA7,
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chunkSize = 18,
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maxChunk = 15
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} = packetConfig
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const bytes = typeof payload === 'string' ? utf8ToBytes(payload) : toUint8Array(payload)
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const chunks = splitUint8Array(bytes, chunkSize)
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if (chunks.length > maxChunk) {
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throw new Error(`分包数量超过上限: ${chunks.length} > ${maxChunk}`)
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}
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return chunks.map((chunk, index) => {
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const packetIndex = index + 1
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const lenByte = ((chunks.length & 0x0F) << 4) | (packetIndex & 0x0F)
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const packet = new Uint8Array(2 + chunk.length)
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packet[0] = head
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packet[1] = lenByte
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packet.set(chunk, 2)
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return packet
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})
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}
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/**
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* 合并多个 A7 分包数据体（去掉前两字节头信息后拼接）。
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*/
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export function concatA7PacketData(packets = []) {
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const sorted = [...packets].sort((a, b) => {
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const indexA = a[1] & 0x0F
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const indexB = b[1] & 0x0F
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return indexA - indexB
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})
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const totalLength = sorted.reduce((sum, packet) => sum + Math.max(packet.length - 2, 0), 0)
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const merged = new Uint8Array(totalLength)
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let offset = 0
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sorted.forEach((packet) => {
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const body = packet.slice(2)
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merged.set(body, offset)
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offset += body.length
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})
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return merged
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}
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