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2 stack calculator

I have an Intel build assignment. I need to write a calculator that uses 2 stacks. For example, I have an expression like 23 + 4/2 ^ 4 $. So $ indicates the end of the expression. I will do this to have two stacks, one for numbers, one for operators, and push and pop them according to the priority of the operator.

I need how I can use 2 stacks for two different purposes at the same time. As long as I know, the esp register indicates the place for variables on the stack to pop up last or hit new. But if I have only one esp register, how can I have two stacks?

Thanks in advance...

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6 answers

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mov ecx,256
L1: call ReadInt
    push eax          ;push the integer to where esp=1 points
    add esp,ecx       ;esp=1+256=257, now esp points to 257.

    call ReadChar     ;read operand
    cmp al,endChar    ;compare with end sign=$
    je next       
    push al           ;push operand to where esp=257 points
    sub esp,ecx       ;esp=257-256=1, now esp is in the original position
    loop L1
next:
...

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By the way, I have "1> .. \ main.asm (46): error A2149: byte register cannot be the first operand" error for (push al)? what is the question?

thanks...

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