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Wiki page start changed with summary [Added the missing number(64) in the statement.] by Zubair Sharief

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Zubair Sharief 2016-11-18 06:20:34 -08:00 committed by apache
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@ -120,7 +120,7 @@ Pointers are also just integers. Either 32 or 64 bits. They refer to a location
When we want signed numbers, we center our ranges AROUND 0. So bytes (chars) can go from -128 to 127, shorts from -32768 to 32767, and so on. By default all of the types are signed (except pointers) UNLESS you put an "unsigned" in front of them. You can also place "signed" in front to explicitly say you want the type to be signed. //A catch - on ARM systems chars often are unsigned by default//. Also be aware that it is common on 64 bit systems to have long integers be 64 bit, and on 32 bit they switch to being 32 bits. Windows is the exception here and long integers will remain 32 bit (we are skipping windows 16 bit coding here).
Pointers follow the instruction set mode. For 32 bit architectures pointers are 32 bits in size, and are bits in size on 64 bit architectures. Standard ARM systems are 32 bit, except for very new 64 bit ARM systems. On x86, 64 bit has been around for a while, and so you will commonly see both. This is the same for PowerPC and MIPS as well.
Pointers follow the instruction set mode. For 32 bit architectures pointers are 32 bits in size, and are 64 bits in size on 64 bit architectures. Standard ARM systems are 32 bit, except for very new 64 bit ARM systems. On x86, 64 bit has been around for a while, and so you will commonly see both. This is the same for PowerPC and MIPS as well.
Memory to a machine is just a big "spreadsheet" of numbers. Imagine it as a spreadsheet with only 1 column and a lot of rows. Every cell can store 8 bits (a byte). If you "merge" rows (2, 4, 8) you can store more values as above. But when you merge rows, the next row number doesn't change. You also could still address the "parts" of the merged cell as bytes or smaller units. In the end pointers are nothing more than a number saying "go to memory row 2943298 and get me the integer (4 bytes) located there" (if it was a pointer to an integer). The pointer itself just stores the PLACE in memory where you find the data. The data itself is what you get when you de-reference a pointer.