simonzsx / haskell-little-man-computer

A simple implementation of Little Man Computer in Haskell(Denoted as LMC in later docs)

Haskell-Little-Man-Computer

A simple implementation of Little Man Computer in Haskell(Denoted as LMC in later docs)

Detailed discription of LMC: http://en.wikipedia.org/wiki/Little_man_computer

###LMC Instruction Code Reference

• INP: ask user to type in a number then store it in the accumulator
• STA: get the value in the accumulator then store it in the mailbox of the given label
• LDA: get the value in the mailbox of the given label then store it in the accumulator
• ADD: get the value in the mailbox of the given label, add it with the accumulator and store
• SUB: subtract the value in mailbox of the given label from the value in the accumulator
• OUT: print out the value in the accumulator
• BRA: jump to the instruction with the given label
• BRZ: check the value in the accumulator. if it is zero jump to the instruction with the given label
• BRP: check the value in the accumulator. if it is positive, jump to the instruction with the given label
• HLT: terminate the program
• DAT: declare a variable with an initial value. The initial value is zero by default

###Rules:

1.Every line must contain an instruction

2.Each line starts with either a label or a space and/or end with a comment.

3.DAT instructions will appear only at the bottom of a program

###Sample Code:

####A) INP STA FIRST INP STA SECOND LDA FIRST SUB SECOND OUT HLT FIRST DAT SECOND DAT

####B) INP LOOP SUB ONE // Label this memory address as LOOP, The instruction will then subtract the value stored at address ONE from the accumulator OUT BRZ QUIT // If the accumulator value is 0, jump to the memory address labeled QUIT BRA LOOP // If the accumulator value is not 0, jump to the memory address labeled LOOP QUIT HLT // Label this memory address as QUIT ONE DAT 1 // Store the value 1 in this memory address, and label it ONE (variable declaration)