#define NOOP 7

#define div 8

#define imul 9

#define xidiv 10

#define andf 11

#define xorf 12

#define cmpge 13

#define jmae 14

#define jmnae 15

#define bsf 16

#define bsr 17

#define jne 18

#define push 19

#define pop 20

int readandfParse (FILE *, char *, char *, char *, char *, char *);

int translateSymbol (char labelArray [MAXNUMLABELS] [MAXLABELLENGTH], int labelAddress [MAXNUMLABELS], int, char *);

int isNumber (char *);

void testRegArg (char *);

void testAddrArg (char *);

int main (int argc, char *argv [])

{

char *inFileString, *outFileString;

FILE *inFilePtr, *outFilePtr;

int address;

char label [MAXLINELENGTH], opcode [MAXLINELENGTH], arg0 [MAXLINELENGTH],

arg1 [MAXLINELENGTH], arg2 [MAXLINELENGTH], argTmp [MAXLINELENGTH];

int i;

int numLabels=0;

int num;

int addressField;

char labelArray [MAXNUMLABELS] [MAXLABELLENGTH];

int labelAddress [MAXNUMLABELS];

if (argc! = 3) {

printf ("error: usage: %s <assembly-code-file> <machine-code-file>\n",

argv [0]);

exit (1);

}

inFileString = argv [1];

outFileString = argv [2];

inFilePtr = fopen (inFileString, "r");

if (inFilePtr == NULL) {

printf ("error in opening %s\n", inFileString);

exit (1);

}

outFilePtr = fopen (outFileString, "w");

if (outFilePtr == NULL) {

printf ("error in opening %s\n", outFileString);

exit (1);

}

/* map symbols to addresses */

/* assume address start at 0 */

for (address=0; readandfParse (inFilePtr, label, opcode, arg0, arg1, arg2);

address++) {

/*

printf ("%d: label=%s, opcode=%s, arg0=%s, arg1=%s, arg2=%s\n",

address, label, opcode, arg0, arg1, arg2);

*/

/* check for illegal opcode */

if (strcmp (opcode, "add") && strcmp (opcode, "nand") &&

strcmp (opcode, "lw") && strcmp (opcode, "sw") &&

strcmp (opcode, "beq") && strcmp (opcode, "jalr") &&

strcmp (opcode, "halt") && strcmp (opcode, "noop") &&

strcmp (opcode,". fill") && strcmp (opcode, "div") &&

strcmp (opcode, "imul") && strcmp (opcode, "xidiv") &&

strcmp (opcode, "andf") && strcmp (opcode, "xorf") &&

strcmp (opcode, "cmpge") && strcmp (opcode, "jmae") &&

strcmp (opcode, "jmnae") && strcmp (opcode, "bsr") &&

strcmp (opcode, "jne") && strcmp (opcode, "bsf") &&

strcmp (opcode, "push") && strcmp (opcode, "pop"))

{

printf ("error: unrecognized opcode %s at address %d\n", opcode,

address);

exit (1);

}

/* check register fields */

if (! strcmp (opcode, "add") ||! strcmp (opcode, "nand") ||

! strcmp (opcode, "lw") ||! strcmp (opcode, "sw") ||

! strcmp (opcode, "beq") ||! strcmp (opcode, "jalr") ||

! strcmp (opcode, "div") ||! strcmp (opcode, "imul") ||

! strcmp (opcode, "xidiv") ||! strcmp (opcode, "andf") ||

! strcmp (opcode, "xorf") ||! strcmp (opcode, "cmpge") ||

! strcmp (opcode, "bsf") ||! strcmp (opcode, "bsr"))

{

testRegArg (arg0);

testRegArg (arg1);

}

if (! strcmp (opcode, "nand") ||! strcmp (opcode, "add") ||

! strcmp (opcode, "div") ||! strcmp (opcode, "imul") ||

! strcmp (opcode, "xidiv") ||! strcmp (opcode, "andf") ||

! strcmp (opcode, "xorf") ||! strcmp (opcode, "cmpge"))

{

testRegArg (arg2);

}

/* check addressField */

if (! strcmp (opcode, "lw") ||! strcmp (opcode, "sw") ||

! strcmp (opcode, "beq") ||! strcmp (opcode, "jmae") ||

! strcmp (opcode, "jmnae") ||! strcmp (opcode, "jne"))

{

testAddrArg (arg2);

}

if (! strcmp (opcode,". fill"))

{

testAddrArg (arg0);

}

/* check for enough arguments */

if ( (strcmp (opcode, "halt") && strcmp (opcode, "noop") &&

strcmp (opcode,". fill") && strcmp (opcode, "jalr") &&

strcmp (opcode, "bsf") && strcmp (opcode, "bsr") &&

strcmp (opcode, "pop") && strcmp (opcode, "push") &&

strcmp (opcode, "je") && arg2 [0] =='\0') ||

(! strcmp (opcode, "jalr") && arg1 [0] =='\0') ||

(! strcmp (opcode,". fill") && arg0 [0] =='\0'))

{

printf ("error at address %d: not enough arguments\n", address);

exit (2);

}

if (label [0]! = '\0') {

/* check for labels that are too long */

if (strlen (label) >= MAXLABELLENGTH) {

printf ("label too long\n");

exit (2);

}

/* make sure label starts with letter */

if (! sscanf (label, "% [a-zA-Z]", argTmp)) {

printf ("label doesn't start with letter\n");

exit (2);

}

/* make sure label consists of only letters andf numbers */

sscanf (label, "% [a-zA-Z0-9]", argTmp);

if (strcmp (argTmp, label)) {

printf ("label has character other than letters andf numbers\n");

exit (2);

}

/* look for duplicate label */

for (i=0; i<numLabels; i++) {

if (! strcmp (label, labelArray [i])) {

printf ("error: duplicate label %s at address %d\n",

label, address);

exit (1);

}

}

/* see if there are too many labels */

if (numLabels >= MAXNUMLABELS) {

printf ("error: too many labels (label=%s) \n", label);

exit (2);

}

strcpy (labelArray [numLabels], label);

labelAddress [numLabels++] = address;

}

}

for (i=0; i<numLabels; i++) {

/* printf ("%s = %d\n", labelArray [i], labelAddress [i]); */

}

/* now do second pass (print machine code, with symbols filled in as

addresses) */

rewind (inFilePtr);

for (address=0; readandfParse (inFilePtr, label, opcode, arg0, arg1, arg2);

address++) {

if (! strcmp (opcode, "add")) (atoi (arg1) << 16) else if (! strcmp (opcode, "nand")) (atoi (arg1) << 16) else if (! strcmp (opcode, "div")) (atoi (arg0) << 19) else if (! strcmp (opcode, "imul")) (atoi (arg0) << 19) else if (! strcmp (opcode, "xidiv")) (atoi (arg0) << 19) else if (! strcmp (opcode, "andf")) atoi (arg2);

else if (! strcmp (opcode, "xorf")) (atoi (arg1) << 16) else if (! strcmp (opcode, "cmpge")) (atoi (arg0) << 19) else if (! strcmp (opcode, "jalr")) (atoi (arg0) << 19) else if (! strcmp (opcode, "bsf"))

num = (bsf << 22) else if (! strcmp (opcode, "push")) {

num = (push << 22);

} else if (! strcmp (opcode, "pop")) {

num = (pop << 22);

} else if (! strcmp (opcode, "halt")) {

num = (HALT << 22);

} else if (! strcmp (opcode, "noop")) {

num = (NOOP << 22);

} else if (! strcmp (opcode, "bsr")) (atoi (arg1) << 16);

else if (! strcmp (opcode, "lw") ||! strcmp (opcode, "sw") ||

! strcmp (opcode, "beq") ||! strcmp (opcode, "jmae") ||

! strcmp (opcode, "jmnae") ||! strcmp (opcode, "jne")) {

/* if arg2 is symbolic, then translate into an address */

if (! isNumber (arg2)) {

addressField = translateSymbol (labelArray, labelAddress,

numLabels, arg2);

/*

printf ("%s being translated into %d\n", arg2, addressField);

*/

if (! strcmp (opcode, "beq") ||! strcmp (opcode, "jmae") ||! strcmp (opcode, "jmnae")) {

addressField = addressField-address-1;

}

} else {

addressField = atoi (arg2);

}

if (addressField < - 32768 || addressField > 32767) {

printf ("error: offset %d out of range\n", addressField);

exit (1);

}

/* truncate the offset field, in case it's negative */

addressField = addressField & 0xFFFF;

if (! strcmp (opcode, "beq")) (atoi (arg0) << 19) else if (! strcmp (opcode, "jmae")) (atoi (arg0) << 19) else if (! strcmp (opcode, "jmnae")) (addressField);

else if (! strcmp (opcode, "jne"))

num = (jne << 22) else {

/* lw or sw */

if (! strcmp (opcode, "lw")) addressField;

else addressField;

}

} else if (! strcmp (opcode,". fill")) {

if (! isNumber (arg0)) {

num = translateSymbol (labelArray, labelAddress, numLabels,

arg0);

} else {

num = atoi (arg0);

}

}

/* printf (" (address %d): %d (hex 0x%x) \n", address, num, num); */

fprintf (outFilePtr, "%d\n", num);

}

exit (0);

}

/*

* Read andf parse a line of the assembly-language file. Fields are returned

* in label, opcode, arg0, arg1, arg2 (these strings must have memory already

* allocated to them).

*

* Return values:

* 0 if reached end of file

* 1 if all went well

*

* exit (1) if line is too long.

*/

int readandfParse (FILE *inFilePtr, char *label, char *opcode, char *arg0,char *arg1, char *arg2)

{

char line [MAXLINELENGTH];

char *ptr = line;

/* delete prior values */

label [0] = opcode [0] = arg0 [0] = arg1 [0] = arg2 [0] = '\0';

/* read the line from the assembly-language file */

if (fgets (line, MAXLINELENGTH, inFilePtr) == NULL) {

/* reached end of file */

return (0);

}

/* check for line too long */

if (strlen (line) == MAXLINELENGTH-1) {

printf ("error: line too long\n");

exit (1);

}

/* is there a label? */

ptr = line;

if (sscanf (ptr, "% [^\t\n]", label)) {

/* successfully read label; advance pointer over the label */

ptr += strlen (label);

}

/*

* Parse the rest of the line. Would be nice to have real regular

* expressions, but scanf will suffice.

*/

sscanf (ptr, "%* [\t\n\r] % [^\t\n\r] %* [\t\n\r] % [^\t\n\r] %* [\t\n\r] % [^\t\n\r] %* [\t\n\r] % [^\t\n\r] ",

opcode, arg0, arg1, arg2);

return (1);

}

int translateSymbol (char labelArray [MAXNUMLABELS] [MAXLABELLENGTH],

int labelAddress [MAXNUMLABELS], int numLabels, char *symbol)

{

int i;

/* search through address label table */

for (i=0; i<numLabels && strcmp (symbol, labelArray [i]); i++) {

}

if (i>=numLabels) {

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