Please take a look at Midi Event Commands, where it's explained that some events like Program Change take only one parameter.
My question is then what do you send along with this event's 2nd parameter's byte, is it 0x00? or you just entirely omit it from the event which doesn't really make sense?
Not all MIDI messages are 3 bytes long. Some are only two, and program change is one of them. For these messages, there is no second data byte.
Related
We used to use the guava cache and we want to change it to caffeine.
We want to set for each entity its own "expiration time", something like - put(K key, V value, long expiration_time).
I saw the 3 functions above and I wonder what exactly they are doing, if you can explain me the meaning ant the operations of each one of them it will be great.
For example, the return value of expireAfterCreate should be the duration we want for this entity from it's creation untill it's expiration? or something else?
I'm also wondering why we have the parameter "currentTime" in both expireAfterRead and expireAfterUpdate if we don't use it in the function?
When we used the guava cache we used the expireAfterAccess, what is the substitution for it in caffeine?
My last question is how can I set a default value for entities without a unique expiration time.
Thank you,
May
When we used the guava cache we used the expireAfterAccess, what is the substitution for it in caffeine?
We mirror the Guava API, so this is also available on the cache builder.
My last question is how can I set a default value for entities without a unique expiration time.
Use expireAfterAccess, expireAfterWrite, or return a constant duration with expireAfter(Expiry).
I saw the 3 functions above and I wonder what exactly they are doing, if you can explain me the meaning ant the operations of each one of them it will be great.
Expiry is a callback interface where a single timestamp value is updated. The invoked method corresponds to the operation performed on the cache entry (created, updated, read). An update or read that should have no effect can return currentDuration to no-op.
For example, the return value of expireAfterCreate should be the duration we want for this entity from it's creation untill it's expiration? or something else?
Yes. However if the expireAfterUpdate returns a custom value (something other than currentDuration), then that overrides the prior expiration duration.
I'm also wondering why we have the parameter "currentTime" in both expireAfterRead and expireAfterUpdate if we don't use it in the function?
This can most often be ignored, but is provided if somehow useful. It is the current nano timestamp from the Ticker (not wall clock time).
We want to set for each entity its own "expiration time", something like - put(K key, V value, long expiration_time).
The callback Expiry is required and generally recommended, because ideally entries are loaded through the cache to avoid stampedes (e.g. LoadingCache). A stampede is when multiple threads lookup the same entry, miss, load it, and overwrite each other putting it in. That wasted work rather than having only one thread perform the load and others wait for the results.
That said, this method is available under Cache.policy().expiresVariably(). Those configuration-specific methods are stashed in that area to offer more power when deemed necessary.
Thank you,
You're very welcome.
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it show warning
I was suppose to arrange the numbers, In order irrespective of the values, but to move 0 come at last.
To learn what you are doing wrong you need to read a book in C. Basic one.
I can point some errors and good practices.
comparison is done by ==. so you should use if(i==0)
After the second for loop you would want to change the value of i to 0. i=0.
the two for loops should be run upto the point when i<n and j<n.
That if(a[i]==0) comparison is not needed.
You don't need the while loop here.
You can print all of them after the for-for looping.
Global variables are used but you should have a good reason to use that.
Index variables are better if declared and defined locally.
what you are trying to do is known as Bubble sort.
Even after understanding all this and following this you get error try to run it through debugger, try small value of n.
Then if you can't, then ask here.
What does backpatching mean ? Please illustrate with a simple example.
Back patching usually refers to the process of resolving forward branches that have been planted in the code, e.g. at 'if' statements, when the value of the target becomes known, e.g. when the closing brace or matching 'else' is encountered.
In intermediate code generation stage of a compiler we often need to execute "jump" instructions to places in the code that don't exist yet. To deal with this type of cases a target label is inserted for that instruction.
A marker nonterminal in the production rule causes the semantic action to pick up.
Some statements like conditional statements, while, etc. will be represented as a bunch of "if" and "goto" syntax while generating the intermediate code.
The problem is that, These "goto" instructions, do not have a valid reference at the beginning(when the compiler starts reading the source code line by line - A.K.A 1st pass). But, after reading the whole source code for the first time, the labels and references these "goto"s are pointing to, are determined.
The problem is that can we make the compiler able to fill the X in the "goto X" statements in one single pass or not?
The answer is yes.
If we don't use backpatching, this can be achieved by a 2 pass analysis on the source code. But, backpatching lets us to create and hold a separate list which is exclusively designed for "goto" statements. Since it is done in only one pass, the first pass will not fill the X in the "goto X" statements because the comipler doesn't know where the X is at first glance. But, it does stores the X in that exclusive list and after going through the whole code and finding that X, the X is replaced by that address or reference.
Backpaching is the process of leaving blank entries for the goto instruction where the target address is unkonown in the forward transfer in the first pass and filling these unknown in the second pass.
Backpatching:
The syntax directed definition can be implemented in two or more passes (we have both synthesized attributes and inherited attributes).
Build the tree first.
Walk the tree in the depth-first order.
The main difficulty with code generation in one pass is that we may not know the target of a branch when we generate code for flow of control statements
Backpatching is the technique to get around this problem.
Generate branch instructions with empty targets
When the target is known, fill in the label of the branch instructions (backpatching).
backpatching is a process in which the operand field of an instruction containing a forward reference is left blank initially. the address of the forward reference symbol is put into this field when its definition is encountered in the program.
Back patching is the activity of filling up the unspecified information of labels
by using the appropriate semantic expression in during the code generation process.
It is done by:
boolean expression.
flow of control statement.
Is the readable file event triggered by a channel becoming readable, or by it being readable? In a file event handler, do I have to read all available input to get a new event triggered in the future? Or can I read only 1 character and return, and if there was more input, my handler will automatically be called again directly? Or not directly, but rather put at the end of the event queue, so this would be the preferred way to do it (maybe not just 1 character but for example 1 line) to prevent one stream from blocking the entire program?
It is triggered by a channel being readable, so you can read only a part of input (or read nothing occasionally, being sure that the handler will be called again). However, reading all available input is better for performance (not necessarily all available bytes: if you read line by line, do gets until it returns -1 for fblocked condition).
The sign of input being exhausted is the true value of [fblocked $channel]. That's why the use case with gets and incomplete line of input is possible: even though the channel is technically readable, just not getsable, the event doesn't fire again until new data arrive.
What does a period with a name before a function mean when calling it in Arduino code (C/C++)?
For example, I am using an OLED display library and one function is called like this:
display.setTextSize(1);
I know what this function does, but what does the syntax mean where there is some variable "display" or something before it?
In other words, why is a function called this way versus a normal call with just the function name and input?
"display" is an instance of an object, or a reference to some global/system variable. The "setTextSize" method is a member of that object. The end result means that you are setting the text size of, or on, "display".
This lets you do things more concisely by being able to say display.setTextSize(1), foo.setTextSize(1) and bar.setTextSize(1) without having to specify unique functions for each different item on which you are setting the text size.
Within setTextSize you will probably see "this". "this" in only this one instance means "display". If you used bar.setTextSize(1), "this" would mean "bar" and so on.
I could be incredibly wrong, but I think its got to do with structures. In the arduino environment there's a few different functions that revolve around using serial communication. They have it set up as a library that gets called on whenever you use Serial.something();
The something could be any of the functions that is part of serial, like Serial.read();
EDIT forgot to put a source in. http://arduino.cc/en/Reference/Serial
Apologies if I'm way off, still new at this, and also can't figure out how to just make a comment.