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//
// SDLGlobals.m
// SmartDeviceLink-iOS
//
// Created by Joel Fischer on 8/5/15.
// Copyright (c) 2015 smartdevicelink. All rights reserved.
//
#import "SDLGlobals.h"
static const NSUInteger maxProxyVersion = 4;
@interface SDLGlobals ()
@property (assign, nonatomic) NSUInteger protocolVersion;
@end
@implementation SDLGlobals
+ (instancetype)globals {
static SDLGlobals *sharedGlobals = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedGlobals = [[SDLGlobals alloc] init];
});
return sharedGlobals;
}
- (instancetype)init {
self = [super init];
if (!self) {
return nil;
}
_protocolVersion = 1;
_maxHeadUnitVersion = 0;
return self;
}
#pragma mark - Custom Getters / Setters
- (void)setMaxHeadUnitVersion:(NSUInteger)maxHeadUnitVersion {
self.protocolVersion = MIN(maxHeadUnitVersion, maxProxyVersion);
_maxHeadUnitVersion = maxHeadUnitVersion;
}
- (NSUInteger)maxMTUSize {
switch (self.protocolVersion) {
case 1: // fallthrough
case 2: {
// HAX: This was set to 1024 at some point, for an unknown reason. We can't change it because of backward compatibility & validation concerns. The actual MTU for v1/2 is 1500 bytes.
return 1024;
} break;
case 3: // fallthrough
case 4: {
// If the head unit isn't running v3/4, but that's the connection scheme we're using, then we have to know that they could be running an MTU that's not 128k, so we default back to the v1/2 MTU for safety.
if (self.maxHeadUnitVersion > maxProxyVersion) {
return 1024;
} else {
return 131084;
}
} break;
default: {
NSAssert(NO, @"Unknown version number: %@", @(self.protocolVersion));
return 0;
}
}
}
@end
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