The goal of this project is to create a simple virtual machine that is able to interpret programs that are written in a simplified assembler language. To be precise, it consists in a stack machine that is able to calculate simple arithmetical expressions. These very arithmetical expressions are given to the machine in the form of simple assembler programs.
Like every assembler language, abstractVM’s is composed of a sequence of instructions, but with only one instruction per line; a notable difference between other assembler languages. AbstractVM’s is typical
POSSIBLE INSTRUCTIONS:
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comments They begin with a semicolon (;) and end at the end of a line. A comment may be indifferent at the beginning of a line or after an instruction.
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push v Stack the v value at the top. The v value will naturally take one of the following forms: int8(n),int16(n),int32(n),float(z),double(z) or bigdecimal(z). (For example : int16(n)-create an signed 16-bit integer with the value n)
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pop Unstacks the value at the top of the stack. If the stack is empty the program’s execution must stop error.
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clear Clears the stack. Rendering it empty.
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dup Duplicates the value on the top of the stack, and stacks the copy of the value.
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swap Reverses the order of (swaps) the top two values on the stack.
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dump Display each value on the stack from the newest to the oldest, WITHOUT MODIFYING the stack. Each value is separated from the next with a line break.
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assert v --Not Implemented-- Verify that the value at the top of the stack is equal to the one passed as parameter in this instruction. If it’s not the case, the program execution must stop error. The v value, of course, has the same form as those passed as parameter during the push instruction.
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add Unstack the first two values in the stack, add them, and then stack the result. If the number of values in the stack is strictly less than 2, the program execution must stop error.
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sub Unstack the first two values in the stack, substract them, and then stack the result. If the number of values in the stack is strictly less than 2, the program execution must stop error.
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mul Unstack the first two values in the stack, multiply them, and then stack the result. If the number of the values in the stack is strictly less than 2, the program execution must stop error.
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div Unstack the first two values in the stack, divide them, and then stack the result. If the number of the values in the stack is strictly less than 2, the program execution must stop error. Also, if the divisor is equal to 0, the program execution must also stop error.
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mod Unstack the first two values in the stack, calculate their modulo, and then stack the result. If the number of the values in the stack is strictly less than 2, the program execution must stop error. Also, if the divisor is equal to 0, the program execution must also stop error.
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load v Copy the value from the register v and stack it at the top. if the register v does not contain a value, the program execution must stop error.
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store v Unstack the first value and store it to the register v.
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print Make sure that the value at the top of the stack is an 8-bit integer (of this is not the case, see the assert instruction), then interpret it like an ASCII value and display the corresponding character on the standard output.
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exit Quit the program execution that is underway. If this instruction does not appear, despite the fact that all of the instructions have been executed, the execution must stop error.
USAGE EXAMPLE:
with ">" as input and "<" as output
>./abstractVM ressources/example.avm < [RESULT]
>./anstractVM > push int32(2) > push int32(2) > add > exit > ;; < [RESULT]