From 381e730b9b4f07eec97865ed94cff4c189c39ad1 Mon Sep 17 00:00:00 2001
From: Yuchen Pei <me@ypei.me>
Date: Tue, 2 Jan 2018 15:49:12 +0100
Subject: finished first part of project 7

---
 projects/07/VMTranslator.hs | 57 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 projects/07/VMTranslator.hs

(limited to 'projects/07/VMTranslator.hs')

diff --git a/projects/07/VMTranslator.hs b/projects/07/VMTranslator.hs
new file mode 100644
index 0000000..289c0d4
--- /dev/null
+++ b/projects/07/VMTranslator.hs
@@ -0,0 +1,57 @@
+import Data.Char (toUpper)
+import Data.List.Split (splitOn)
+import System.Environment (getArgs)
+
+preamble = "@256\nD=A\n@SP\nM=D\n"
+
+epilogue = "(END)\n@END\n0;JMP"
+
+parse' :: [Char] -> [[Char]] -> Int -> [Char]
+parse' op [] n
+  | op `elem` ["add", "sub", "and", "or"] = pop "M" ++ pop ('M':(f op):"D") ++ push "D"
+  | op `elem` ["eq", "gt", "lt"] = pop "M" ++ pop "M-D" ++ ifThenElse op n
+  | otherwise = pop "M" ++ push (f op:"D")
+    where f "add" = '+'; f "sub" = '-'; f "and" = '&'; 
+          f "or" = '|'; f "neg" = '-'; f "not" = '!'
+
+parse' "push" ["constant", x] _ = "@" ++ x ++ "\nD=A\n" ++ push "D"
+
+push :: [Char] -> [Char]
+push xs = "@SP\nA=M\nM=" ++ xs ++ "\n@SP\nM=M+1\n"
+
+ifThenElse :: [Char] -> Int -> [Char]
+ifThenElse cond n = "@" ++ cond' ++ show n ++ "\nD;J" ++ cond' ++ "\n" ++ push "0"
+                  ++ "@ENDIF" ++ cond' ++ show n ++ "\n0;JMP\n(" ++ cond' ++ show n ++ ")\n" 
+                  ++ push "-1" ++ "(ENDIF" ++ cond' ++ show n ++ ")\n"
+  where cond' = toUpper <$> cond
+
+pop :: [Char] -> [Char]
+pop xs = "@SP\nAM=M-1\nD=" ++ xs ++ "\n"
+
+parseline :: [[Char]] -> Int -> [Char] -> [Char]
+parseline [] _ acc = acc
+parseline (line:lines) n acc = parseline lines (n + 1) (acc ++ parse' cmd target n)
+  where cmd:target = words line
+
+stripJunk :: [Char] -> [[Char]]
+stripJunk = filter (not . isEmptyLine) . fmap (head . splitOn "//") . lines . replCrWithNl
+
+isEmptyLine :: [Char] -> Bool
+isEmptyLine = null . filter (not . flip elem " \t") 
+
+parseCode :: [Char] -> [Char]
+parseCode xs = preamble ++ (parseline (stripJunk xs) 0 "") ++ epilogue
+
+replCrWithNl :: [Char] -> [Char]
+replCrWithNl = fmap cr2nl 
+  where cr2nl '\r' = '\n'
+        cr2nl c = c
+
+--input = "push constant 17\npush constant 17\neq"
+
+main = do
+  args <- getArgs
+  let filename = head args
+  code <- readFile $ filename
+  writeFile (head (splitOn "." filename) ++ ".asm") (parseCode code)
+  --}
-- 
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