====== The Elements of Computing Systems, 2ed ======

<file text asm.lark>
%import common.WS
%import common.CPP_COMMENT
%import common.INT
%import common.WORD

%ignore WS
%ignore CPP_COMMENT

start: (LABEL | ainstr | cinstr)*

LABEL: "(" WORD ")"

ainstr: "@" SYMBOL

SYMBOL: WORD
      | INT
      | "R" "0".."15"
      | "SP"
      | "LCL"
      | "ARG"
      | "THIS"
      | "THAT"
      | "KBD"
      | "SCREEN"

cinstr: (DEST "=")? COMP (";" JUMP)?

// not satisfied with this; could it be cleaner?
DEST: "A" "D"? "M"?
    | "A"? "D" "M"?
    | "A"? "D"? "M"

JUMP: "JGT"
    | "JEQ"
    | "JGE"
    | "JLT"
    | "JNE"
    | "JLE"
    | "JMP"
</file>

<file text vm.lark>
%import common.WS
%import common.CPP_COMMENT
%import common.INT
%import common.SIGNED_INT

%ignore WS
%ignore CPP_COMMENT

start: (stackop | arithop)*

stackop: (PUSH|POP) SEGMENT INDEX

PUSH: "push"
POP: "pop"

arithop: ADD
       | SUB
       | NEG
       | EQ
       | GT
       | LT
       | AND
       | OR
       | NOT

ADD: "add"
SUB: "sub"
NEG: "neg"
EQ: "eq"
GT: "gt"
LT: "lt"
AND: "and"
OR: "or"
NOT: "not"

SEGMENT: "argument"
       | "local"
       | "static"
       | "constant"
       | "this"
       | "that"
       | "pointer"
       | "temp"

INDEX: INT
</file>

{{tag>compsci electronics programming}}