initial commit

1 files changed, 333 insertions, 0 deletions

diff --git a/compiler.c b/compiler.c
new file mode 100644
index 0000000..18983be
--- /dev/null
+++ b/compiler.c
@@ -0,0 +1,333 @@
+/* Assembler for LC */

+

+#include <stdlib.h>

+#include <stdio.h>

+#include <string.h>

+#define MAXLINELENGTH 1000

+#define MAXNUMLABELS 65536

+#define MAXLABELLENGTH 7 /* includes the null character termination */

+

+#define ADD 0

+#define NAND 1

+#define LW 2

+#define SW 3

+#define BEQ 4

+#define JALR 5

+#define HALT 6

+#define NOOP 7

+

+/*

+ * Read and 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

+readAndParse(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) {

+	printf("error: missing label %s\n", symbol);

+	exit(1);

+    }

+

+    return(labelAddress[i]);

+}

+

+int

+isNumber(char *string)

+{

+    /* return 1 if string is a number */

+    int i;

+    return( (sscanf(string, "%d", &i)) == 1);

+}

+

+/*

+ * Test register argument; make sure it's in range and has no bad characters.

+ */

+void

+testRegArg(char *arg)

+{

+    int num;

+    char c;

+

+    if (atoi(arg) < 0 || atoi(arg) > 7) {

+	printf("error: register out of range\n");

+	exit(2);

+    }

+    if (sscanf(arg, "%d%c", &num, &c) != 1) {

+	printf("bad character in register argument\n");

+	exit(2);

+    }

+}

+

+/*

+ * Test addressField argument.

+ */

+void

+testAddrArg(char *arg)

+{

+    int num;

+    char c;

+

+    /* test numeric addressField */

+    if (isNumber(arg)) {

+	if (sscanf(arg, "%d%c", &num, &c) != 1) {

+	    printf("bad character in addressField\n");

+	    exit(2);

+	}

+    }

+}

+

+/*

+ * main function

+ */

+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; readAndParse(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") ) {

+	    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")) {

+	    testRegArg(arg0);

+	    testRegArg(arg1);

+	}

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

+	    testRegArg(arg2);

+	}

+

+	/* check addressField */

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

+		!strcmp(opcode, "beq")) {

+	    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")

+	      && 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 and numbers */

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

+	    if (strcmp(argTmp, label)) {

+	        printf("label has character other than letters and 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; readAndParse(inFilePtr, label, opcode, arg0, arg1, arg2);

+	    address++) {

+	if (!strcmp(opcode, "add")) {

+	    num = (ADD << 22) | (atoi(arg0) << 19) | (atoi(arg1) << 16)

+		    | atoi(arg2);

+	} else if (!strcmp(opcode, "nand")) {

+	    num = (NAND << 22) | (atoi(arg0) << 19) | (atoi(arg1) << 16)

+		    | atoi(arg2);

+	} else if (!strcmp(opcode, "jalr")) {

+	    num = (JALR << 22) | (atoi(arg0) << 19) | (atoi(arg1) << 16);

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

+	    num = (HALT << 22);

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

+	    num = (NOOP << 22);

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

+		   !strcmp(opcode, "beq")) {

+	    /* 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")) {

+		    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")) {

+		num = (BEQ << 22) | (atoi(arg0) << 19) | (atoi(arg1) << 16)

+		    | addressField;

+	    } else {

+		/* lw or sw */

+		if (!strcmp(opcode, "lw")) {

+		    num = (LW << 22) | (atoi(arg0) << 19) |

+			    (atoi(arg1) << 16) | addressField;

+		} else {

+		    num = (SW << 22) | (atoi(arg0) << 19) |

+			    (atoi(arg1) << 16) | 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);

+}

+