//
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// RHSocketVariableLengthDecoder.m
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// RHSocketKitDemo
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//
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// Created by zhuruhong on 16/2/15.
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// Copyright © 2016年 zhuruhong. All rights reserved.
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//
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#import "RHSocketVariableLengthDecoder.h"
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#import "RHSocketException.h"
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#import "RHSocketUtils.h"
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#import "RHSocketPacketContext.h"
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@implementation RHSocketVariableLengthDecoder
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- (instancetype)init
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{
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if (self = [super init]) {
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_maxFrameSize = 65536;
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_countOfLengthByte = 2;
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_reverseOfLengthByte = YES;
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}
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return self;
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}
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- (NSInteger)decodeData:(NSData *)downstreamData output:(id<RHSocketDecoderOutputProtocol>)output
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{
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NSUInteger headIndex = 0;
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//先读区2个字节的协议长度 (前2个字节为数据包的长度)
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while (downstreamData && downstreamData.length - headIndex > _countOfLengthByte) {
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NSData *lenData = [downstreamData subdataWithRange:NSMakeRange(headIndex, _countOfLengthByte)];
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//长度字节数据，可能存在高低位互换，通过数值转换工具处理
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NSUInteger frameLen = (NSUInteger)[RHSocketUtils valueFromBytes:lenData reverse:_reverseOfLengthByte];
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if (frameLen >= _maxFrameSize - _countOfLengthByte) {
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[RHSocketException raiseWithReason:@"[Decode] Too Long Frame ..."];
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return -1;
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}//
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//剩余数据，不是完整的数据包，则break继续读取等待
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if (downstreamData.length - headIndex < _countOfLengthByte + frameLen) {
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break;
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}
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//数据包(长度＋内容)
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NSData *frameData = [downstreamData subdataWithRange:NSMakeRange(headIndex, _countOfLengthByte + frameLen)];
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RHSocketLog(@"[Log]: frameData: %@", frameData);
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//去除数据长度后的数据内容
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RHSocketPacketResponse *ctx = [[RHSocketPacketResponse alloc] init];
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ctx.object = [frameData subdataWithRange:NSMakeRange(_countOfLengthByte, frameLen)];
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//责任链模式，丢给下一个处理器
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if (_nextDecoder) {
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[_nextDecoder decode:ctx output:output];
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} else {
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[output didDecode:ctx];
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}
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//调整已经解码数据
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headIndex += frameData.length;
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}//while
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return headIndex;
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}
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- (NSInteger)decode:(id<RHDownstreamPacket>)downstreamPacket output:(id<RHSocketDecoderOutputProtocol>)output
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{
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id object = [downstreamPacket object];
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if (![object isKindOfClass:[NSData class]]) {
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[RHSocketException raiseWithReason:@"[Decode] object should be NSData ..."];
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return -1;
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}
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return [self decodeData:object output:output];
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}
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@end
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