From a8bd2cac6d7b3d71f2ff3d9ce655e65a827d5775 Mon Sep 17 00:00:00 2001
From: "Juan J. Martinez" <jjm@usebox.net>
Date: Sun, 25 Sep 2022 20:14:20 +0100
Subject: Attempt at mul

---
 src/Micro/Asm/Sdcc.hs | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/src/Micro/Asm/Sdcc.hs b/src/Micro/Asm/Sdcc.hs
index 238fe2e..3aa9a36 100644
--- a/src/Micro/Asm/Sdcc.hs
+++ b/src/Micro/Asm/Sdcc.hs
@@ -1,6 +1,7 @@
 module Micro.Asm.Sdcc where
 
 import qualified Micro.Ast as A
+import Text.Parsec (SourcePos, sourceColumn, sourceLine)
 
 toIdent :: A.Ident -> String
 toIdent id = "_" ++ id
@@ -23,6 +24,9 @@ toInit (A.Type t) (A.Num v _)
   | otherwise = ".dw " ++ show v
 toInit _ v = ".dw " ++ show v
 
+posToIdent :: SourcePos -> String
+posToIdent p = "l" ++ show (sourceLine p) ++ "$" ++ show (sourceColumn p)
+
 header :: String -> [String]
 header version = [";", "; File created by Micro v" ++ version ++ " (SDCC)", ";"]
 
@@ -38,6 +42,26 @@ area name = "\n\t.area " ++ name
 globl :: String -> String
 globl id = "\t.globl " ++ id
 
+mul8 :: A.Expr -> A.Expr -> SourcePos -> [String]
+mul8 a b p = do
+  let loop = posToIdent p
+  let loop0 = loop ++ "z"
+  oCode (emit a)
+    ++ [ "\tor a",
+         "\tjr z, " ++ toIdent loop0,
+         "\tld b, a",
+         "\tdec b",
+         "\tjr z, " ++ toIdent loop0
+       ]
+    ++ oCode (emit b)
+    ++ [ "\tld c, a",
+         toLabel loop True,
+         "\tadd c",
+         "\tdjnz "
+           ++ toIdent loop,
+         toLabel loop0 True
+       ]
+
 data Output = Output
   { oPre :: [String],
     oInit :: [String],
@@ -74,6 +98,15 @@ emit x =
       o {oCode = oCode (emit a) ++ ["\tsub #" ++ show v]}
     (A.BinOp A.Minus _ a b) ->
       o {oCode = oCode (emit a) ++ ["\tld c, a"] ++ oCode (emit b) ++ ["\tld b, a", "\tld a, c", "\tsub b"]}
+    (A.BinOp A.Mul _ _ (A.Num 0 _)) ->
+      o {oCode = ["\txor a"]}
+    (A.BinOp A.Mul _ _ (A.Num 1 _)) -> o
+    (A.BinOp A.Mul _ a (A.Num 2 _)) ->
+      o {oCode = oCode (emit a) ++ ["\tsla a"]}
+    (A.BinOp A.Mul _ a (A.Num v _)) ->
+      o {oCode = oCode (emit a) ++ ["\tld c, a"] ++ replicate (fromInteger v - 1) "\tadd c"}
+    (A.BinOp A.Mul p a b) -> do
+      o {oCode = mul8 a b p}
     (A.BinOp A.Assign _ (A.Variable id _) b) ->
       o {oCode = oCode (emit b) ++ ["\tld (" ++ toIdent id ++ "), a"]}
     _ -> o {oCode = [";; unimplemented " ++ show x]}
-- 
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