CS270 Colorado State University











=====================
Pass Two in Assembler
=====================

Output of Pass 0 and Pass 1
    
    
    
    
    ./LC3assem test.asm test.LC3 >& test.out
    
    
    
    Pass 0 or parser generates a singly linked list
        


            .ORIG x3000
            ADD R1, R0, #15       ; R1 = 15
            AND R0, R0, #0        ; R0 = 0
INCR0       ADD R0, R0, #1        ; R0++
            LD  R2, INCR0         ; R2 = M
            ADD R2, R2, #1        ; R2++
            ST  R2, INCR0         ; M = R2
            ADD R1, R1, #-1       ; R1--
            BRp x3001             ; If R1 > 0, GOTO: x3001
            HALT
            .END

        
  
    Pass 1  assigns addresses to each instruction and inserts labels into
            symbol table
        
        
        
        
        
        
        
        
        
        
   
   
    Pass 2 determines offset.
    
        Example 1: LD R2, INCR0
    
            
            
            

            
            
            
            
        Example 2: BRp x3001
            
            
            
            
            
            
            
            
            
            
            

=======================
Pass Three in Assembler
=======================

    
    
    
    Write a file header and function header for pass_three.
    
    Based on the opcode and other fields in insn_t construct an instruction.
    
    Check that immediates and offsets fit within provided number of bits.
    
    Write the instruction to the output file.
    
    
    
    fprintf
    
    
    sprintf
    
    
    
    
    
    

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mstrout@cs.colostate.edu, 10/20/08