• Continue to read Chapter 9 Language Translation
• Labs start up again Wednesday after break

largest.as

summer.as

• Syntax: Covered in chapter one; Refine notation
• Also deal with Meaning
• Levels of the machine: Multi-level model

• Translate Java:

  z = (x + y); 

• To Assembler:

  copy 	ax, x
  add	ax, y
  copy 	cn1, ax 
  copy	ax, cn1
  copy	z, ax 

• R1: <n>j -> //as sequence of letters and/or digits that begins with a letter//
  replaces
  R1: <name> -> //a sequence of letters and/or digits that begins with a letter//
  The new R1 says
  "change <n>j into a sequence of letters and/or digits that begins with a letter."

• R2: <e>i -> <n>j
  where "e" stands for "expression"
  Example
<e>1 -> <n>3 -> x
  or
<e>1 ->* x
• R3: <s>k -> <n>j = <e>i;
  where "s" stands for "statement"
  It says "<s>k" can be replaced by
  "<n>j = <e>i;"

derivation	rule

<s>1		R3: <s>1 -> <n>2 = <e>3;
<n>2 = <e>3;	R1: <n>2 -> ans
ans = <e>3;	R2: <e>3 -> <n>4
ans = <n>4;	R1: <n>4 -> data
ans = data; 

• R4: <e>i -> ( <e>j + <e>k )
• R5: <e>i -> ( <e>j * <e>k )

ANS = (X + (Y * Z));



derivation		rule

s1			R3: s1 -> n2 = e3;
n2 = e3;		R1: n2 -> ANS
ANS = e3;		R4: e3 -> (e4 + e5)
ANS = (e4 + e5);	R2: e4 -> n6
ANS = (n6 + e5);	R1: n6 -> X
ANS = (X + e5);		R5: e5 -> (e7 * e8)
ANS = (X + (e7 * e8));	R2: e7 -> n9
ANS = (X + (n9 * e8));	R1: n9 -> Y
ANS = (X + (Y * e8));	R2: e8 -> n10
ANS = (X + (Y * n10));	R1: n10 -> Z
ANS = (X + (Y * Z));