int relative_mode(int *disp){
int PC;
char *temp;
/* Clean '@' or '#' */
if((OPERAND1[0] == '@') || (OPERAND1[0] == '#')){
temp = &OPERAND1[1];
strcpy(OPERAND1, temp);
}
if(!search_SYMTAB(OPERAND1)){
printf("ERROR. %s is not found. It's an undeclared SYMBOL\n", OPERAND1);
exit(0);
}
PC = (int)strtol(LOC, NULL, 16) + OPCODE_format; // PC point to next instruction.
/* try PC relative first */
*disp = SYMBOL_ADDR - PC;
if((*disp >= -2048) && (*disp < 2048)){
return 1;
}
/* try Base relative */
*disp = SYMBOL_ADDR - BASE;
if(*disp < 4096){
return 0;
}
/* else (invalid addressing mode) */
else{
printf("ERROR! Invalid Addressing Mode.\n");
exit(1);
}
}
//Pass 1
void PASS_ONE()
{
FILE * fp1,*fp2; //file pointers
char line[100], s1[100], s2[100], s3[100], s4[100],startingADDRESS[5], saveLOCCTR[5];
int t,flag_SYMTAB, flag_OPTAB;
printf("Enter the input file name :");
scanf("%s",in_file); //input file name
fp1 = fopen(in_file, "r"); //corresponding file opened
if(fp1 == NULL) //if '.txt' not in entered file name
{
strcat(in_file, ".txt"); //concatenating '.txt'
fp1 = fopen(in_file, "r");
if(fp1 == NULL)
{
printf("Could not open source file!!\n");
exit(0);
}
}
strcpy(out_file, in_file);
out_file[strlen(out_file)-4] = '\0';
strcat(out_file, "-intermediate.txt"); //to get intermediate file name
fp2 = fopen(out_file, "w");
if(fp2 == NULL)
{
printf("Could not open Intermediate file!!\n");
exit(0);
}
//fgets(line, 100, fp1);//For column headers
//Read first line
fgets(line, 100 ,fp1); //reading a line of the input
t = sscanf(line,"%s %s %s %s",s1,s2,s3,s4); //t stores the number of words read
if(t==2) //two words read
{
strcpy(s3, s2); //shifting the words read
strcpy(s2, s1);
strcpy(s1, "");
}
char temp[10];
if(strcmp(s2,"START")==0) //start line
{
strcpy(LOCCTR,s3);
make_length(LOCCTR,temp,4);
line[strlen(line)-1] = '\0';
if(t==1)
fprintf(fp2, "%s %s %s",temp,line," Syntax error : less arguments");
else if(t>3)
fprintf(fp2, "%s %s %s",temp,line," Syntax error : more arguments");
else
fprintf(fp2, "%s %s",temp,line);//Write to Intermediate file
fprintf(fp2,"\n");
fgets(line, 100 ,fp1);//Read next line
t = sscanf(line,"%s %s %s %s",s1,s2,s3,s4);
if(t==2)
{
strcpy(s3, s2);
strcpy(s2, s1);
strcpy(s1, "");
}
}
else //if START was not found
{
strcpy(LOCCTR, "0000");
printf("Syntax Error : NO START found!!\n");
}
strcpy(startingADDRESS, LOCCTR);
while(!feof(fp1) && (strcmp(s2, "END")!=0))
{
flag_SYMTAB = 0;flag_OPTAB = 0;
strcpy(saveLOCCTR, LOCCTR);
if(line[0] != '#')//Not a comment line
{
if(t==3)//Symbol exists in Label Field
{
if(search_SYMTAB(s1))//Label exists in SYMTAB
flag_SYMTAB = 1;
else
insert_SYMTAB(s1,LOCCTR);
}
strcpy(saveLOCCTR, LOCCTR);
char * OPCODE = search_OPTAB(s2);
if(OPCODE != NULL)
increment_LOCCTR(3);
else if(strcmp(s2, "WORD") == 0) //WORD detected
increment_LOCCTR(3);
else if(strcmp(s2, "RESW") == 0) //RESW detected
increment_LOCCTR(3 * atoi(s3));
else if(strcmp(s2, "RESB") == 0) //RESB detected
increment_LOCCTR(atoi(s3));
else if(strcmp(s2, "BYTE") == 0) //BYTE detected
increment_LOCCTR(find_length_BYTE(s3));
else
{
increment_LOCCTR(3);
flag_OPTAB = 1;//OPCODE not found and is not an assembler directive
}
}
make_length(saveLOCCTR,temp,4);
strcpy(saveLOCCTR,temp);
char write[100];//Line to write in Intermediate file
line[strlen(line)-1] = '\0';//Remove newline character from line read so taht it writes error on same line
if(flag_OPTAB == 0 )
{
if(flag_SYMTAB == 0)
sprintf(write, "%s %s",saveLOCCTR, line);
else
sprintf(write,"%s %s %s",saveLOCCTR, line, "Duplicate Symbol");
}
else
{
if(flag_SYMTAB == 0)
sprintf(write,"%s %s %s",saveLOCCTR, line, "Invalid Operation Code");
else
sprintf(write,"%s %s %s %s",saveLOCCTR, line, "Duplicate Symbol", "Invalid Operation Code");
}
if(t==1)
fprintf(fp2, "%s %s",write," Syntax error : less arguments");
else if(t>3)
fprintf(fp2, "%s %s",write," Syntax error : more arguments");
else
fprintf(fp2, "%s",write);//Write to Intermediate file
fprintf(fp2,"\n");
//Read next line
fgets(line, 100, fp1);
t = sscanf(line,"%s %s %s %s",s1,s2,s3,s4);
if(t==2)
{
strcpy(s3, s2);
strcpy(s2, s1);
strcpy(s1, "");
}
}
make_length(LOCCTR,temp,4);
//Write last line to Intermediate file
fprintf(fp2, "%s %s",temp, line);
fclose(fp1);
fclose(fp2);
//Computing Program Length
int start, location,l;
char length[5];
sscanf(startingADDRESS, "%x", &start);
sscanf(LOCCTR, "%x", &location);
l = location - start;
itoa(l, length, 16); //getting the length of the code in a string
strcpy(out_file, in_file);
out_file[strlen(out_file)-4] = '\0';
strcat(out_file, "-length.txt");
fp2 = fopen(out_file, "w");
if(fp2 != NULL)
fprintf(fp2, "%s", length);
fclose(fp2); //closing file pointer
}
//pass II
void PASS_TWO()
{
FILE * fp1,*fp2,*fp3;
char line[100], s1[100], s2[100], s3[100], s4[100], startADDRESS[5], length[5], name[100];
//s1 is Location, s2 is Label, s3 is Opcode, s4 is Operand
char * symbolADDRESS;
char OBJECTCODE[100] ;
int t,flag_SYMTAB,main_flag = 0,linecounter = 0;
printf("Enter the intermediate file name :");
scanf("%s",im_file);
fp1 = fopen(im_file, "r"); //opening intermediate file
if(fp1 == NULL)
{
strcat(im_file, ".txt");
fp1 = fopen(im_file, "r");
if(fp1 == NULL)
{
printf("Could not open Intermediate file!!\n");
exit(0);
}
}
loadSYMTAB_from_file(); //loading symbol table
strcpy(obj_file, im_file);
obj_file[strlen(obj_file)-17] = '\0';
strcat(obj_file, "-object.txt");
fp2 = fopen(obj_file, "w");
if(fp2 == NULL)
{
printf("Could not open Object file!!\n");
exit(0);
}
//Read first line
fgets(line, 100 ,fp1);
linecounter++;
t = sscanf(line,"%s %s %s %s",s1,s2,s3,s4);
if(t==3)
{
strcpy(s4, s3);
strcpy(s3, s2);
}
if(strcmp(s3,"START")==0)
{
strcpy(startADDRESS, s1);
strcpy(name, s2);//s2 != s3
fgets(line, 100 ,fp1);//Read next line
linecounter++;
t = sscanf(line,"%s %s %s %s",s1,s2,s3,s4);
if(t==3)
{
strcpy(s4, s3);
strcpy(s3, s2);
}
}
else
{
strcpy(startADDRESS, "0000");
strcpy(name, "UNNAMED");
}
//Getting Program Length
char S[100];
strcpy(S, im_file);
S[strlen(S)-17] = '\0';
strcat(S, "-length.txt");
fp3 = fopen(S, "r");
fscanf(fp3, "%s",length);
fclose(fp3);
//Writing Header Record
char temp1[7], temp2[7];
make_length(startADDRESS, temp1, 6);
make_length(length, temp2, 6);
fprintf(fp2,"H|%s|%s|%s",name,temp1,temp2);
fprintf(fp2,"\n");
//Initialse text record
fprintf(fp2, "T|%s|%s",temp1,length);
while(!feof(fp1) && (strcmp(s3, "END")!=0))
{
flag_SYMTAB = 0;
if(s2[0] != '#')//Not a comment line
{
char * OPCODE = search_OPTAB(s3);
if(OPCODE != NULL)//OPCODE found in OPTAB
{
if(s4!=NULL)//There is a symbol in operand field
{
symbolADDRESS = search_SYMTAB(s4);
if(symbolADDRESS != NULL)
make_length(symbolADDRESS, temp1, 4);
if(symbolADDRESS == NULL)//Operand does not exist in SYMTAB
{
printf("Line %d : Error : Symbol is not defined\n",linecounter);
main_flag = 1;
flag_SYMTAB = 1;
}
}
else//No symbol in operand field
strcpy(symbolADDRESS,"0000");
//Assemble object code instruction
strcpy(OBJECTCODE, OPCODE);
if(symbolADDRESS != NULL)
strcat(OBJECTCODE, temp1);
}
else if(OPCODE==NULL && (strcmp(s3, "BYTE") == 0))
convert_BYTE(s4,OBJECTCODE);
else if(OPCODE==NULL && (strcmp(s3, "WORD") == 0))
convert_WORD(s4,OBJECTCODE);
else//OPCODE is RESW or RESB
strcpy(OBJECTCODE, "");
if(strcmp(OBJECTCODE,"") != 0)
fprintf(fp2, "|%s",OBJECTCODE);//Add object code to text
}
//Read next line
fgets(line, 100, fp1);
linecounter++;
t = sscanf(line,"%s %s %s %s",s1,s2,s3,s4);
if(t==3)
{
strcpy(s4, s3);
strcpy(s3, s2);
}
}
//Write End Record
fprintf(fp2,"\n");
make_length(startADDRESS, temp1, 6);
fprintf(fp2,"E|%s",temp1);
fclose(fp1);
fclose(fp2);
strcpy(obj_file, im_file);
obj_file[strlen(obj_file)-17] = '\0';
strcat(obj_file, "-object.txt");
if(main_flag == 1) //error in file
remove(obj_file); //removing the object file as error has been detected
}
void convert_Object(void){
char *temp;
int n, i, x, b, p, e;
int disp = 0;
int j;
char str[3];
get_OPformat();
/* if is format 1 */
if(OPCODE_format == 1){
OBJECT_CODE = instPtr->Opcode;
OBJECT_ox = 1; // need to generate OBJECT CODE
convert_ObToString(); // convert int object code to string.
}
/* else if is format 2 */
else if(OPCODE_format == 2){
OBJECT_CODE = (instPtr->Opcode) << 8; // shit left 1 Byte
if(OPERAND_ox == 2){
OBJECT_CODE += ((reg_value(OPERAND1) << 4) | reg_value(OPERAND2)); // 2 registers
}
else{
OBJECT_CODE += (reg_value(OPERAND1) << 4); // 1 register
}
OBJECT_ox = 1; // need to generate OBJECT CODE
convert_ObToString(); // convert int object code to string.
}
/* else (format 3) */
else if(OPCODE_format == 3){
/* if is Immediate addressing */
if(OPERAND1[0] == '#'){
n = 0;
i = 1;
}
/* else if is Indirect addressing */
else if(OPERAND1[0] == '@'){
n = 1;
i = 0;
}
/* else (simple) */
else{
i = 1;
n = 1;
}
/* Calculate displacement,
if OPERAND1 is immediate address constant */
if((OPERAND1[0] == '#') && (OPERAND1[1] >= '0') && (OPERAND1[1] <= '9')){
disp = atoi(&OPERAND1[1]); // we don't need #
b = 0;
p = 0;
}
/* else if PC relative */
else if(relative_mode(&disp)){
b = 0;
p = 1;
}
/* else (BASE relative) */
else{
b = 1;
p = 0;
}
/* if is index address */
if((OPERAND_ox == 2) && (OPERAND2[0] == 'X')){
x = 1;
}
/* else (not index address) */
else{
x = 0;
}
e = 0; // format 3
/* exception RSUB <-- L */
if(!strcmp(OPCODE, "RSUB")){
n = 1;
i = 1;
x = 0;
b = 0;
p = 0;
e = 0;
disp = reg_L;
}
/* generate object code */
OBJECT_CODE = (instPtr->Opcode) << 16; // shift left 16 bits
OBJECT_CODE += ((n << 17) + (i << 16) + (x << 15) + (b << 14) + (p << 13) + (e << 12));
OBJECT_CODE |= (disp & 0x00000FFF) ;
OBJECT_ox = 1; // need to generate OBJECT CODE
convert_ObToString(); // convert int object code to string.
}
/* else if is format 4 */
else if(OPCODE_format == 4){
/* if is Immediate addressing */
if(OPERAND1[0] == '#'){
n = 0;
i = 1;
}
/* else if is Indirect addressing */
else if(OPERAND1[0] == '@'){
n = 1;
i = 0;
}
/* else (simple) */
else{
i = 1;
n = 1;
}
/* Calculate address,
if OPERAND1 is immediate address constant */
if((OPERAND1[0] == '#') && (OPERAND1[1] >= '0') && (OPERAND1[1] <= '9')){
disp = atoi(&OPERAND1[1]); // we don't need #
b = 0;
p = 0;
}
/* else (direct addressing) */
else{
/* Clean '@' or '#' */
if((OPERAND1[0] == '@') || (OPERAND1[0] == '#')){
temp = &OPERAND1[1];
strcpy(OPERAND1, temp);
}
/* search SYMTAB */
if(search_SYMTAB(OPERAND1) == 0){
printf("ERROR! %s is not found. It's an invalid SYMBOL\n", OPERAND1);
exit(0);
}
b = 0;
p = 0;
disp = SYMBOL_ADDR;
/* Relocation */
relocate(0); // store address
}
/* if is index address */
if((OPERAND_ox == 2) && (OPERAND2[0] == 'X')){
x = 1;
}
/* else (not index address) */
else{
x = 0;
}
e = 1; // format 4
/* generate object code */
OBJECT_CODE = (instPtr->Opcode) << 24; // shift left 16 bits
OBJECT_CODE += ((n << 25) + (i << 24) + (x << 23) + (b << 22) + (p << 21) + (e << 20));
OBJECT_CODE += disp;
OBJECT_ox = 1; // need to generate OBJECT CODE
convert_ObToString(); // convert int object code to string.
}
/* else if OPCODE = 'BYTE', then */
else if(!strcmp(OPCODE, "BYTE")){
/* if string */
if(OPERAND1[0] == 'C'){
OBJECT_CODE = (int)OPERAND1[2];
for(j = 3, S_L = 1; OPERAND1[j] != '\''; j++, S_L++){
OBJECT_CODE = (int)OPERAND1[j] + (OBJECT_CODE << 8);
}
}
/* else (char) */
else{
str[0] = OPERAND1[2];
str[1] = OPERAND1[3];
str[2] = '\0';
OBJECT_CODE = (int)strtol(str, NULL, 16);
S_L = 1;
}
OBJECT_ox = 1;
convert_ObToString();
}
/* else if OPCODE = 'WORD', then */
else if(!strcmp(OPCODE, "BYTE")){
OBJECT_CODE = atoi(OPERAND1);
OBJECT_ox = 1;
S_L = 1;
convert_ObToString();
}
/* else if OPCODE = 'BASE', then */
else if(OPCODE_format == 7){
/* search SYMTAB */
if(search_SYMTAB(OPERAND1) == 0){
printf("ERROR! %s is not found. It's an invalid SYMBOL\n", OPERAND1);
exit(0);
}
BASE = SYMBOL_ADDR;
OBJECT_ox = 0;
}
else if(OPCODE_format == 0){
OBJECT_ox = 0;
}
else{
/* Set ERROR Flag */
printf("ERROR.\n");
exit(0);
}
// printf("x = %d, b = %d, p = %d, e = %d, disp = %X\n", x, b, p, e, disp); // for testing
return ;
}
