And maybe, if I'm their President, people at school like Ethel Muggs or Jughead or even Betty will stop looking at me like I'm just the daughter of criminals, like I'm a criminal too. We're out there fighting a holy war, Mom. I need something I can use as a shield against everything that's coming our way. Protection from everybody out there who hates us, who's out for our blood.
WPbytes in sizeas compiled in the small model with Borland and Microsoft compilers with optimization on opt and off no opt. ASM ; Assembler subroutine to perform a bit checksum on the file ; opened on the passed-in handle. Stores the result in the ; passed-in checksum variable.
Returns 1 for success, 0 for error. Optimization makes code faster, but without proper design, optimization just creates fast slow code. Well, then, how are we going to improve our design?
Know the Territory Just why is Listing 1. The C library implements the read function by calling DOS to read the desired number of bytes. I figured this out by watching the code execute with a debugger, but you can buy library source code from both Microsoft and Borland.
That means that Listing 1. For starters, DOS functions are invoked with interrupts, and interrupts are among the slowest instructions of the x86 family CPUs. Then, DOS has to set up internally and branch to the desired function, expending more cycles in the process.
Finally, DOS has to search its own buffers to see if the desired byte has already been read, read it from the disk if not, store the byte in the specified location, and return.
All of that takes a long time—far, far longer than the rest of the main loop in Listing 1. In short, Listing 1. You can verify this for yourself by watching the code with a debugger or using a code profiler, but take my word for it: How can we speed up Listing 1.
It should be clear that we must somehow avoid invoking DOS for every byte in the file, and that means reading more than one byte at a time, then buffering the data and parceling it out for examination one byte at a time.
The results confirm our theories splendidly, and validate our new design. As shown in Table 1. To the casual observer, read and getc would seem slightly different but pretty much interchangeable, and yet in this application the performance difference between the two is about the same as that between a 4.
Make sure you understand what really goes on when you insert a seemingly-innocuous function call into the time-critical portions of your code. In other words, know the territory!
Spend your time improving the performance of the code inside heavily-used loops and in the portions of your programs that directly affect response time. Let C do what it does well, and use assembly only when it makes a perceptible difference.
Always Consider the Alternatives Listing 1. Like readgetc calls DOS to read from the file; the speed improvement of Listing 1. Easier, yes, but not faster. Every invocation of getc involves pushing a parameter, executing a call to the C library function, getting the parameter in the C library codelooking up information about the desired stream, unbuffering the next byte from the stream, and returning to the calling code.
That takes a considerable amount of time, especially by contrast with simply maintaining a pointer to a buffer and whizzing through the data in the buffer inside a single loop.
There are four reasons that many programmers would give for not trying to improve on Listing 1. The code is already fast enough. The C library conveniently handles the buffering of file data, and it would be a nuisance to have to implement that capability.
The second reason is the hallmark of the mediocre programmer. Know when optimization matters—and then optimize when it does! The third reason is often fallacious. C library functions are not always written in assembly, nor are they always particularly well-optimized.
As an example, consider Listing 1. Clearly, you can do well by using special-purpose C code in place of a C library function—if you have a thorough understanding of how the C library function operates and exactly what your application needs done.
The key is the concept of handling data in restartable blocks; that is, reading a chunk of data, operating on the data until it runs out, suspending the operation while more data is read in, and then continuing as though nothing had happened.
At any rate, Listing 1. Always consider the alternatives; a bit of clever thinking and program redesign can go a long way. Know How to Turn On the Juice I have said time and again that optimization is pointless until the design is settled.
When that time comes, however, optimization can indeed make a significant difference.BDSM Story – The Weekend – Chapter 3 by Sardonicus. The next morning, I actually slept longer than I usually would have, so I had to actually rush about to get ready for my meeting with Maggie. photo credit Nasa / Goddard Space Flight Center / Reto Stöckli Chapter 9 Arguments of Definition What is an argument of definition?
States what someone/something can be Gives what something includes/excludes How is a term defined? Definition describes: Conclusion Formal Definition - those found.
CHAPTER 1. Loomings. Call me Ishmael. Some years ago—never mind how long precisely—having little or no money in my purse, and nothing particular to interest me on shore, I thought I would sail about a little and see the watery part of the world. Everything's an argument chapter 8 summary Toronto Woodstock everything's an argument chapter 8 summary changing a name of a business, Stockport make dissertation hypothesis on internet technologies online Clarence-Rockland, Grand Rapids.
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custom thesis proposal on freedom for money Trafford looking for. Everything’s An Argument, Ch. 8 Worksheet “Structuring and Argument” What is a claim?
• The statement in which you hope to prove. Data and reason support claims%(1).