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99 lines
3.7 KiB
Text
Executable file
99 lines
3.7 KiB
Text
Executable file
The basics of the ZealC language. Requirements: Knowledge of basic integer mathematics and number sense.
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There are 4 main types of symbols. A symbol is just a fancy name for something with a name.
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We have:
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- Functions
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- Variables
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- Definitions
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- Classes
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$HL$//This is a variable
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I64 my_var;
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//This is another variable of a different $UL,1$type$UL,0$.
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U8 my_u8;
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$HL,0$
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Variables are declared as certain $UL,1$types$UL,0$. There are types for numbers. You just saw two of them above, I64 and U8.
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The compiler gives us 8 types for numbers. These types are different $UL,0$$UL,1$sizes$UL,0$ of numbers, and if they are $UL,1$signed$UL,0$ or $UL,0$$UL,1$unsigned$UL,0$.
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A $UL,1$byte$UL,1$$UL,0$ is 8 bits. The range of numbers you can store in a byte is 0 to 255. In a signed byte that range is from -128 to 127.
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* Unsigned types cannot be a negative value.
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* Only signed types can store negative numbers.
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Now you might be thinking, how does it know if a number is negative or not? After all, a number is just a series of bits!
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The way we store a signed number is we reserve a single bit in the number to tell us whether or not it is signed.
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If we have a number that is 8 bits wide, then we have to use a single bit as a $UL,0$$UL,1$sign bit$UL,0$.
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The sign bit is always the highest bit available.
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In a signed byte, bits #0-6 will be used to store the actual value of the number.
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Bit #7 will be the sign bit. If the sign bit is 1, then it is a negative number.
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# 7 6 5 4 3 2 1 0
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$FG,4$0b 0 0 0 0 0 0 1 1$FG$ => $FG,1$3$FG$
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sign the number "3" in binary
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If it a number is signed that means that it cannot use all of its bits to represent a value.
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Therefore, the range of numbers it can represent is split between the negative side and the positive side of numbers.
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$HL,0$$FG,6$ Unsigned byte range
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$FG,5$ Signed byte range
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|--------------------------|
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$FG,0$-255 -127 0 127 255$FG$
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Now, you can imagine how this plays out with numbers that are bigger than 1 byte.
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For 2-byte numbers, the unsigned range becomes 0 to 65535, and the signed range becomes -32768 to 32767.
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The sign bit is bit #15.
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Unsigned number types:
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$HL$U8 -- 1 byte (8 bits) unsigned number
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I8 -- 1 byte (8 bits - 1 sign bit = 7 bits) signed number
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U16 -- 2 byte (16 bits) unsigned number
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I16 -- 2 byte (16 bits - 1 sign bit = 15 bits) signed number
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U32 -- 4 byte (32 bits) unsigned number
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I32 -- 4 byte (32 bits - 1 sign bit = 31 bits) signed number
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U64 -- 8 byte (64 bits) unsigned number
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I64 -- 8 byte (64 bits - 1 sign bit = 63 bits) signed number
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$HL,0$
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Try it out on the command line:
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Declare a I8 variable named 'x' and assign(=) it the value 3, and press ENTER.
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$FG,1$C:/Home>$FG,2$I8 x = 3;$FG$
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Now type $FG,2$Bts(&x, 7);$FG$ and press ENTER. This will set bit #7 to 1. Bts is "Bit test and set". Don't forget the $FG,2$&$FG$.
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Now if you want to see the value of x, you can simply type $FG,2$x;$FG$ and press ENTER.
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$FG,1$C:/Home>$FG,2$x;
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$FG,1$0.000007s ans=0xFFFFFFFFFFFFFF83=-125$FG$
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Ignore the extra F's for now. You are interested in this hexadecimal '83' value.
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So what happened? When you flipped the sign bit, the number 3 became -125. It started counting up from -128, instead of 0.
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You can type $FG,2$"%8tb\n", x;$FG$ to print out the number in binary, if you wish.
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For most purposes in programming, an $HL$I64$HL,0$ number will work fine.
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You are currently reading this on a 64-bit operating system, running on a 64-bit computer.
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We hear about the greatness of 64-bit machines all the time, but what exactly does that mean?
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The CPU is designed to work with 64-bit numbers, natively.
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