Putting C: Dev-Cpp bin and C: Dev-Cpp on your PATH. The following assumes that you are logged on with Administrator privileges. Since that is the (amazingly insecure) default with Microsoft, you may assume that this is the case if you do not know otherwise. Local Environment Setup. If you are still willing to set up your environment for C, you need to have the following two softwares on your computer. This will be used to type your program. Examples of few editors include Windows Notepad, OS Edit command, Brief, Epsilon, EMACS, and vim or vi.
By Thomas Carriero
This tutorial gives you easy-to-follow instructions, with screenshots, for setting up a compiler (the MINGW compiler), a tool that will let youturn the code that youwrite into programs, and Code::Blocks Step 1: Download Code::Blocks
Step 2: Install Code::Blocks
Step 3: Running in Code::BlocksYou will be prompted with a Compilers auto-detection window:When you get the compiler auto-detection window, just hit OK.Code::Blocks may ask if you want to associate it as the default viewer forC/C++ files--I'd suggest you do.Click on the File menu, and under 'New', select 'Project..' The following window will come up: Click on 'Console Application' and hit the 'Go' button. Click next until you get to the Language Selection Dialog: You'll be asked to choose whether you want to use C or C++. If you'renot sure, use C++. Otherwise, choose based on the language you are learning. (You can find tutorials here on both C and C++.) After clicking 'Next', Code::Blocks will then prompt you with where you'd like to save the consoleapplication: I'd recommend you put it in its own folder, as it may createseveral files (this is especially true if you create other types of projects). You will need to give your project a name, anything willbe fine. Clicking 'Next' again will prompt you to set up your compiler: You don't need to do anything here. Just accept the defaults by hitting'Finish'. You can now open the main.cpp file on the left: (You may need to expand the contents of the 'Sources' folder if you don't see main.cpp.) At this point, you will have your main.cpp file, which you can modify if you like. For now, it just says 'Hello World!', so we can run it as is. Hit F9, which will first compile it and then run it. You now have a running program! You can simply edit main.cpp and then hit F9 to compile it and run it again. Now that you've finished setting your compiler up, it's time to learn toprogram: Intro toC++ (or if you're learning C, Intro to C). Troubleshooting
The most common error people see if things don't work is a message like
'CB01 - Debug' uses an invalid compiler. Probably the toolchain path within the compiler options is not setup correctly?! Skipping..'
First, make sure that you downloaded the right version of Code::Blocks, theone that included MinGW. If that doesn't solve the problem, it is likely aproblem with compiler auto-detection. Here's how you can check your current'auto-detected' state. Go to 'Settings|Compiler and Debugger..'. Then on theleft, choose 'Global Compiler Settings' (it has a gear icon) and on the right,select the 'Toolchain executables' tab. This tab has a 'Auto-detect' buttonthat you can use. That might fix the problem--if it doesn't, you can manuallyfill out the form. Here's a screenshot demonstrating what things look like onmy system. Change the path marked 'Compiler's installation directory' if youinstalled to a different location, and make sure everything else is filled in as shown.
Once you've done that, try pressing F9 again to see if you get a running program.
Continue to Intro toC++ (or Intro to C).
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This is a guide to setting up paging. It will teach you the basic concepts behind paging and how it can help you with your OS. This example will concentrate on Legacy Non-PSE Non-PAE paging (See also Setting Up Paging With PAE).
Paging is a term that refers to the management of the computer's virtual memory. If you have not yet created a physical memory manager, please read and follow Page Frame Allocation before continuing with this article.
Basic Paging
Paging allows you to have more than one virtual address space mapped into the physical address space. The MMU uses what is called a Page Directory to map virtual addresses to physical addresses.
Page Directory - A table in memory which the MMU uses to find the page tables. Each index in the Page Directory is a pointer to a Page table. Page Table - A table in memory that describes how the MMU should translate a certain range of addresses. Each index in a Page Table contains the physical memory address to which a certain page should be mapped. Creating a Blank Page Directory
The first step is to create a blank page directory. The page directory is blank because we have not yet created any page tables where the entries in the page directory can point.
Note that all of your paging structures need to be at page-aligned addresses (i.e. being a multiple of 4096). If you have already written a page frame allocator then you can use it to allocate the first free page after your kernel for the page directory. If you have not created a proper page allocator, simply finding the first free page-aligned address after the kernel will be fine, but you should write the page frame allocator as soon as possible. Another temporary solution (used in this tutorial) is to simply declare global objects with __attribute__((align(4096))). Note that this is a GCC extension. It allows you to declare data aligned with some mark, such as 4KiB here. We can use this because we are only using one page directory and one page table. Please note that on the real world, dynamic allocation is too basic to be missing, and paging structures are constantly being added, deleted, and modified. For now, just use static objects;
Little snitch gsa.apple.com. Now that we have a page directory, we need to blank it. The page directory should have exactly 1024 entries. We will set each entry to not present so that if the MMU looks for that page table, it will see that it is not there (..yet. We will add the first page table in a moment).
A page is 'not present' is one which is not (intended to be) used. If the MMU finds one, it will Page Fault. Non-present pages are useful for techniques such as Lazy Loading. It's also used when a page has been swapped to disk, so the Page Fault is not interpreted as an error by the OS. To the OS, it means someone needs a page it swapped to disk, so it is restored. A page fault over a page that was never swapped is a error by which the OS has a reason to kill the process.
Creating Your First Page Table
The second step is to create a basic page table. In this example we choose to fill up the whole first page table with addresses for the MMU. Because each page is 4 kilobytes large, and because each page table has exactly 1024 entries, filling up the whole table causes us to map 4 megabytes of memory. Also, the page directory is 1024 entries long, so everything can map up to 4GiB, the full 32-bit address space. Remembered the non-present page trick? Without it, we would use 16MiB per each paging structure. A single page directory needs 4KiB, but it can map some tables as non-present, effectively removing their space needs.
Now, its time to create a new page table.
We now need to fill each index in the table with an address to which the MMU will map that page. Index 0 (zero) holds the address from where the first page will be mapped. Likewise, index 1 (one) holds the address for the second page and index 1023 holds the address of the 1024th page. That's for the first table. So, to get the page at which a certain index is mapped is as simple as (PageDirIndexOfTable * 1024) + PageTabIndexOfPage. If you multiply that by 4, you'll get the address (in KiB) at which the page will be loaded. For example, page index 123 in table index 456 will be mapped to (456 * 1024) + 123 = 467067. 467067 * 4 = 1868268 KiB = 1824.48046875 MiB = 1.781719207763671875 GiB. It's easy, right?
Put the Page Table in the Page Directory
The third step is to put the newly created page table into our blank page directory. We do this by setting the first entry in the page directory to the address of our page table.
Enable Paging
The final step is to actually enable paging. First we tell the processor where to find our page directory by putting it's address into the CR3 register. Because C code cannot directly access the computer's registers, we will need to use assembly code to access CR3. The following assembly is written for GAS. If you use a different assembler then you will need to translate between this assembly format and the format supported by your assembler.
This small assembly function takes one parameter: the address of the page directory. It then loads the address onto the CR3 register, where the MMU will find it. But wait! Paging is not still enabled. That's what we will do next. We must set the 32th bit in the CR0 register, the paging bit. This operation also requires assembly code. Once done, paging will be enabled.
Now lets call the functions!
Dev C++ Programs
Paging should now be enabled. Try printing something to screen like 'Hello, paging world!'. If all goes well, congratulations! You've just learned the basics of paging. But there are lots of other things to do with it. You won't be able to almost all of them for now. Just remember that you have a little friend in the CR3 register that will help you one day.
More Advanced Paging Example
Add sections on how to dynamically get and free pages..
Setting Up Dev C Download
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