106 lines
3.3 KiB
Markdown
106 lines
3.3 KiB
Markdown
Veits Virtual Machine
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A virtual machine that executes assembler-like code.
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Performance
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-----------
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Performance is pretty okay on basic, small programs. The included factorial
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function takes 0.1 second on 100000 iterations. As a scale, a Python 3.3 program
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on the same machine using the code:
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``
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def fac(n):
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if n < 2: return 1
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else: return n * fac(n-1)
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fac(12)
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``
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takes about 3.7 seconds on 100000 iterations.
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This does not say anything about overall performance though and I am not
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sure whether this small, funny test has any real value in measuring performance.
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Also, Python is much more feature-rich, so you cannot compare the two at all.
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DISCLAIMER: Parsing takes quite a long time, so try to write your programs as
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concise as possible.
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Instruction set
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---------------
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Up until now, all the operations are executed on integers(hence the
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I\* prefix).
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*Operations overview*:
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* IADD - Adds the two items to each other that are on top of the stack
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and stores the result on top of the stack.
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* ISUB - Subtracts the two items from each other that are on top of the
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stack and stores the result on top of the stack.
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* IMULT - Multiplies the two items to each other that are on top of the
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stack and stores the result on top of the stack.
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* IDIV - Performs a division operation to the two items that are on top
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of the stack and stores the result on top of the stack.
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* IMOD - Performs a modulo operation to the two items that are on top
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of the stack and stores the result on top of the stack.
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* ILT - Checks whether the item on top of the stack is greater than the
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item below it and stores a boolean on top of the stack.
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* IEQ - Checks whether the item on top of the stack is equal to the
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item below it and stores a boolean on top of the stack.
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* IGT - Checks whether the item on top of the stack is smaller than the
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item below it and stores a boolean on top of the stack.
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* ILEQ - Checks whether the item on top of the stack is smaller than or
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equal to the item below it and stores a boolean on top of the stack.
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* IGEQ - Checks whether the item on top of the stack is greater than or
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equal to the item below it and stores a boolean on top of the stack.
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* BR - Jumps to the instruction that is provided as an argument.
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* BRT - Jumps to the instruction that is provided as an argument if the
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value on top of the stack is TRUE.
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* BRF - Jumps to the instruction that is provided as an argument if the
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value on top of the stack is FALSE.
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* ICONST - Puts the argument provided to the operation on top of the
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stack.
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* LOAD - Loads an element from any position on the stack on top of the
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stack(usually used to get function arguments like this: LOAD -3).
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* GLOAD - Loads an element from any position on the data segment on
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top of the stack.
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* STORE - Stores an element on the stack.
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* GSTORE - Stores an element in the data segment.
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* PRINT - Prints the element on top of the stack as character.
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* IPRINT - Prints the element on top of the stack as integer.
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* POP - Pops the element on top of the stack.
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* HALT - Ends the program.
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* CALL - calls a subroutine with a number of arguments.
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* RET - Returns from a subroutine with a return value.
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* FETCH - Fetches a value.
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* IINC -Increments the value on top of the stack by one(equal to ++).
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* IDEC -Decrements the value on top of the stack by one(equal to --).
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