Løsningsforslag til ukeoppgaver 5. november 2009


Oppgave 1
---------

1a   v1 = -17;

Code 12: Instruksjoner kan ikke inneholde negative tall.

Korrekt:
Code   12:  201000000000017  SET       1  0         17  #       17
Code   13:  501000000000001  SUB       1  0          1  # R1 = -
Code   14:  301000000000005  STORE     1  0          5  # v1 = 

1b   v2 = v1 - 1;

Code: 16: Siste parameter i SUB-instruksjonen angir et
_registernummer_, ikke en _verdi_. Angitt kode vil trekke fra
innholdet av register R1, og det er ikke det vi ønsker.

Korrekt:
Code   15:  101000000000005  LOAD      1  0          5  # R1 = v1
Code   16:  203010000000000  SET       3  1          0  # <save operand>
Code   17:  201000000000001  SET       1  0          1  # R1 = 1
Code   18:  501030000000001  SUB       1  3          1  # -
Code   19:  301000000000006  STORE     1  0          6  # v2 = 

1c   v3 = v1*-2;

Code 21+: Instruksjonen som kopierer R1 til R3 mangler.

Korrekt:
Code   20:  101000000000005  LOAD      1  0          5  # R1 = v1
Code   21:  203010000000000  SET       3  1          0  # <save operand>
Code   22:  201000000000002  SET       1  0          2  #       2
Code   23:  501000000000001  SUB       1  0          1  # R1 = -
Code   24:  601030000000001  MUL       1  3          1  # *
Code   25:  301000000000007  STORE     1  0          7  # v3 = 

1d   v4 = 2*v2 + 2;

Code 32+: STORE-instruksjonen mangler.

Korrekt:
Code   26:  201000000000002  SET       1  0          2  # R1 = 2
Code   27:  203010000000000  SET       3  1          0  # <save operand>
Code   28:  101000000000006  LOAD      1  0          6  # R1 = v2
Code   29:  601030000000001  MUL       1  3          1  # *
Code   30:  203010000000000  SET       3  1          0  # <save operand>
Code   31:  201000000000002  SET       1  0          2  # R1 = 2
Code   32:  401030000000001  ADD       1  3          1  # +
Code   33:  301000000000008  STORE     1  0          8  # v4 = 

1e   v5 = v1*3 - v2*2;

Uttrykket skal regnes ut som  ((v1*3)-v2)*2 (slik reglene for RusC
tilsier): 
Code   34:  101000000000005  LOAD      1  0          5  # R1 = v1
Code   35:  203010000000000  SET       3  1          0  # <save operand>
Code   36:  201000000000003  SET       1  0          3  # R1 = 3
Code   37:  601030000000001  MUL       1  3          1  # *
Code   38:  203010000000000  SET       3  1          0  # <save operand>
Code   39:  101000000000006  LOAD      1  0          6  # R1 = v2
Code   40:  501030000000001  SUB       1  3          1  # -
Code   41:  203010000000000  SET       3  1          0  # <save operand>
Code   42:  201000000000002  SET       1  0          2  # R1 = 2
Code   43:  601030000000001  MUL       1  3          1  # *
Code   44:  301000000000009  STORE     1  0          9  # v5 = 


Oppgave 2
---------

    public static void noteCode(int addr, String instrName, int instrNo,
				int op1, int op2, int op3, String comment) {
	if (! doLogCode) return;

	writeLogLine("Code " + fNum(addr,4) + ": " + 
		     fNum(((instrNo*100 + op1)*100 + op2)*10000000000L + op3,16) +
		     "  " + fStr(instrName,8) + fNum(op1,3) + 
		     fNum(op2,3) + fNum(op3,11) + "  # " + comment);
    }

    public static void noteRes(int addr, int nWords, String comment) {
	if (! doLogCode) return;

	writeLogLine("Code " + fNum(addr,4) + ": " + fStr("",18) +
		     fStr("RES",8) + fNum(nWords,17) + "  # " + comment);
    }

    public static void noteUpdate(int addr, long newVal, int op3, String comment) {
	if (! doLogCode) return;

	writeLogLine("---> " + fNum(addr,4) + ": " + fNum(newVal,16) +
		     fNum(op3,27) + "  # " + comment);
    }

    private static String fNum(long n, int w) {
	String s = "" + n;
	while (s.length() < w) s = " " + s;
	return s;
    }

    private static String fStr(String s, int w) {
	while (s.length() < w) s += " ";
	return s;
    }