/*
	Paul Cameron Smith
	CDA 3101 - Comp Org 2
	MIPS Assembler
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_SIZE 100 	// maximum number of lines to parse/store

int getOpcode(char instr[32]){
	int opc;
	if (strcmp(instr, "add") == 0)
		opc = 0;
	else if (strcmp(instr, "addi") == 0)
		opc = 8;
	else if (strcmp(instr, "nor") == 0)
		opc = 0;
	else if (strcmp(instr, "ori") == 0)
		opc = 13;
	else if (strcmp(instr, "sll") == 0)
		opc = 0;
	else if (strcmp(instr, "lui") == 0)
		opc = 15;
	else if (strcmp(instr, "sw") == 0)
		opc = 43;
	else if (strcmp(instr, "lw") == 0)
		opc = 35;
	else if (strcmp(instr, "bne") == 0)
		opc = 5;
	else if (strcmp(instr, "j") == 0)
		opc = 2;
	return opc;
}
int getDecRep(char reg[2]){
	int decrep;
	if (strcmp(reg, "0") == 0)
		decrep = 0;
	else if (strcmp(reg, "1") == 0)
		decrep = 1;
	else if (strcmp(reg, "t0") == 0)
		decrep = 8;
	else if (strcmp(reg, "t1") == 0)
		decrep = 9;
	else if (strcmp(reg, "t2") == 0)
		decrep = 10;
	else if (strcmp(reg, "t3") == 0)
		decrep = 11;
	else if (strcmp(reg, "t4") == 0)
		decrep = 12;
	else if (strcmp(reg, "t5") == 0)
		decrep = 13;
	else if (strcmp(reg, "t6") == 0)
		decrep = 14;
	else if (strcmp(reg, "t7") == 0)
		decrep = 15;
	else if (strcmp(reg, "s0") == 0)
		decrep = 16;
	else if (strcmp(reg, "s1") == 0)
		decrep = 17;
	else if (strcmp(reg, "s2") == 0)
		decrep = 18;
	else if (strcmp(reg, "s3") == 0)
		decrep = 19;
	else if (strcmp(reg, "s4") == 0)
		decrep = 20;
	else if (strcmp(reg, "s5") == 0)
		decrep = 21;
	else if (strcmp(reg, "s6") == 0)
		decrep = 22;
	else if (strcmp(reg, "s7") == 0)
		decrep = 23;
	return decrep;
}

int main(int argc, char **argv){

	char cptr[100];			// where to store temp line
	char label[32], dir[32], instr[32], opands[32], extra[32];
	int num = 0, dat = 0;		// dat is a flag to know
	char labels[MAX_SIZE][32];	// labels
	int	addresses[MAX_SIZE];
	char* operations[100];
	int i = 0, a = 0, pc = 0;

	for (i; i < MAX_SIZE; i++){
		strcpy(labels[i], "");
		addresses[i] = 0;
	}

	/* Pass #1, associate each symbolic label with an address, start @ 0 */

	while (fgets(cptr, sizeof(cptr), stdin) != NULL){		// grabs line from input stream, stores in cptr
		i=0;										// the number of characters in each line (cptr)
		while (cptr[i] != '\0'){						// cptr[i] == null at the end of a line
			i++; 								// parse through each character
		}										// cptr should now be one complete line (includes \n at the end)

		// DO STUFF WITH CPTR
		if ( sscanf( cptr, "%[^:]:\t%s\t%s", label, instr, opands) == 3 && dat == 0){
		// only do this before data (dat = 0)
			//printf("%#010X: ", pc);				//print 0x 8-digit hex line#:
			strcpy(labels[a], label);				// store label in labels[a]
			addresses[a] = pc;						// store pc into addresses[a]
			if ( strcmp(instr, "la") == 0)
				pc+=4;
			//printf(cptr);						//print line contents

		}
		else if (sscanf( cptr, "%[^:]:\t%s\t%d", label, dir, &num) == 3 && dat == 1){
		// do this AFTER data (dat = 1)
			//printf("%#010X: ", pc);				//print 0x 8-digit hex line#:
			strcpy(labels[a], label);				// store label in labels[a]
			addresses[a] = pc;						// store pc into addresses[a]
			if (strcmp(dir,".space") == 0)
				pc += (num - 4);
			//printf(cptr);						//print line contents
		}
		else if (sscanf( cptr, "\t%s\t%s", instr, opands) == 2){
			//printf("%#010X: ", pc);				//print 0x 8-digit hex line#:
			if ( strcmp(instr, "la") == 0)
				pc+=4;
			//printf(cptr);						//print line contents
		}
		else if (sscanf( cptr, "\t%s", extra) == 1){
			if (strcmp(extra, ".data") == 0){
				dat = 1;
				pc -= 4;
			}
			else if (strcmp(extra, ".text") == 0)
				pc -= 4;
		}
		pc+=4;			// move onto the lext adress
		a++;
	}

	rewind(stdin);			// puts me back at the beginning of stdin

	/* Pass #2, translate instructions into corresponding machine code*/
	i = 0, pc = 0, dat = 0;
	int op = 0, rs = 0, rt = 0, rd = 0, shamt = 0, funct = 0, immed = 0, targaddr = 0;
	char s[2], t[2], d[2];
	int bin = 0;

	while (fgets(cptr, sizeof(cptr), stdin) != NULL) {

		//sscanf( cptr, "%[^:]: %s %s", label, instr, opands);
		//printf("%s %s %s ///", label, instr, opands);

		// we dont care about the labels anymore, thanks to the first loop
		// we only care about the instructions, and
		// depending on the instr, we do things with the operands.

		if (sscanf( cptr, "\t%s", extra) == 1){
			if (strcmp(extra, ".data") == 0){		// if we hit data
				break;						// leave the loop, we dont need anything else
			}
			else if (strcmp(extra, ".text") == 0)	// we have all the labels we need from 1st loop
				continue;						//ignore, do nothing first line
			// else
			// 	printf("You don't belong here...");
		}

		bin = 0;

		if ( sscanf( cptr, "%[^:]:\t%s\t%s", label, instr, opands) == 3){
			printf("0x%08X: ", pc);				//print 0x 8-digit hex line#:
		}
		else if	(sscanf( cptr, "\t%s\t%s", instr, opands) == 2){
			printf("0x%08X: ", pc);				//print 0x 8-digit hex line#:
		}

		if ( strcmp(instr, "la") == 0){
			bin = 0;
			strcpy(instr, "lui");
		// lui
			if( sscanf(opands, "$%[^,],%s", t, label) == 2){
				op = getOpcode(instr);
				rt = getDecRep("1");
				bin = (op << 5) | 0;
				bin = (bin << 5) | rt;			// now get immed by grabbing top 16 bits from label
				for (i = 0; i < a; i++){
					if (strcmp(labels[i], label) == 0){
						immed = (addresses[i] >> 16);
						break;
					}
				}
				bin = (bin << 16) | immed;
				printf("0x%08X\n", bin);
			// split
				pc += 4;
				bin = 0;
				printf("0x%#08X: ", pc);		//print 0x 8-digit hex line#:
				// do ori instr
				strcpy(instr, "ori");
			// ori
				bin = 0;
				op = getOpcode(instr);
				rs = getDecRep("1");		// get rs
				rt = getDecRep(t);			// get rt;
				bin = (bin&op);
				bin = (op << 5) | rs;
				bin = (bin << 5) | rt;
				for (i = 0; i < a; i++){
					if (strcmp(labels[i], label) == 0){
						immed = (addresses[i] & 65535);
						break;
					}
				}
				bin = (bin << 16) | immed;
				printf("0x%08X\n", bin);		//print line contents
			}
		}
		//for every other instr (add, addi, nor, ori, sll, lui, sw, lw, bne, j
		else if ( strcmp(instr, "add") == 0){
			if ( sscanf(opands, "$%[^,],$%[^,],$%s", d, s, t) == 3){
				op = getOpcode(instr);
				rs = getDecRep(s);			// get rs;
				rt = getDecRep(t);			// get rt;
				rd = getDecRep(d);			// get rd;
				bin = (op << 10) | rs;
				bin = (bin << 5) | rt;
				bin = (bin << 5) | rd;
				bin = (bin << 5); 			// shamt is 0 for add, no need to or
				funct = 32;				// get funct;
			 	bin = (bin << 6) | funct;
			 	printf("0x%08X\n", bin);		//print line contents
			}
		}	// 99% correct I think lol
		else if ( strcmp(instr, "addi") == 0){
			if ( sscanf(opands, "$%[^,],$%[^,],%d", t, s, &immed) == 3){
				op = getOpcode(instr);
				rs = getDecRep(s);			// get rs;
				rt = getDecRep(t);			// get rt;
				bin = (op << 5) | rs;
				bin = (bin << 5) | rt;
				immed = (immed & 0x0000FFFF);
				immed = (immed | 0x0000);
			 	bin = (bin << 16) | immed;
			 	printf("0x%08X\n", bin);		//print line contents
			}
		}	// completed
		else if ( strcmp(instr, "nor") == 0){
			if ( sscanf(opands, "$%[^,],$%[^,],$%s", d, s, t) == 3){
				op = getOpcode(instr);
				rs = getDecRep(s);			// get rs;
				rt = getDecRep(t);			// get rt;
				rd = getDecRep(d);			// get rd;
				bin = (op << 5) | rs;
				bin = (bin << 5) | rt;
				bin = (bin << 5) | rd;
				bin = (bin << 5); 			// shamt is 0 for add, no need to or
				funct = 39;				// get funct;
			 	bin = (bin << 6) | funct;
			 	printf("0x%08X\n", bin);		//print line contents
			}
		}	// nothin personal, kid
		else if ( strcmp(instr, "ori") == 0){
			if ( sscanf(opands, "$%[^,],$%[^,],%d", t, s, &immed) == 3)
			{
				bin = 63;
				op = getOpcode(instr);
				rs = getDecRep(s);			// get rs
				rt = getDecRep(t);			// get rt;
				bin = (bin&op);
				bin = (bin << 5) | rs;
				bin = (bin << 5) | rt;
				bin = (bin << 16) | immed;	// get immed;
				printf("0x%08X\n", bin);		//print line contents
			}
		}	// annihilated
		else if ( strcmp(instr, "sll") == 0){
			if ( sscanf(opands, "$%[^,],$%[^,],%d", d, t, &shamt) == 3){
				op = getOpcode(instr);
				rd = getDecRep(d);
				rt = getDecRep(t);
				bin = (op << 5) | 0;
				bin = (bin << 5) | rt;
				bin = (bin << 5) | rd;
				bin = (bin << 5) | shamt;
				bin = (bin << 6);
				printf("0x%08X\n", bin);
			}
		}	// destroyed
		else if ( strcmp(instr, "lui") == 0){
			if ( sscanf(opands, "$%[^,],%d", t, &immed) == 2){
				op = getOpcode(instr);
				rt = getDecRep(t);
				bin = (op << 5) | 0;
				bin = (bin << 5) | rt;
				bin = (bin << 16) | immed;
				printf("0x%08X\n", bin);		//print line contents
			}
		}	// pwn'd
		else if ( strcmp(instr, "sw") == 0){
			if ( sscanf(opands, "$%[^,],%d($%[^)]", t, &immed, s) == 3){
				op = getOpcode(instr);
				rs = getDecRep(s);
				rt = getDecRep(t);
				bin = (op << 5) | rs;
				bin = (bin << 5) | rt;
				bin = (bin << 16) | immed;
				printf("0x%08X\n", bin);		//print line contents
			}
		}	// easy game
		else if ( strcmp(instr, "lw") == 0){
			if ( sscanf(opands, "$%[^,],%d($%[^)]", t, &immed, s) == 3){
				op = getOpcode(instr);
				rs = getDecRep(s);
				rt = getDecRep(t);
				bin = (op << 5) | rs;
				bin = (bin << 5) | rt;
				bin = (bin << 16) | immed;
				printf("0x%08X\n", bin);		//print line contents
			}
		}	// easy life
		else if ( strcmp(instr, "bne") == 0){
			if ( sscanf(opands, "$%[^,],$%[^,],%s", s, t, label) == 3){
				op = getOpcode(instr);
				rs = getDecRep(s);
				rt = getDecRep(t);
				bin = (op << 5) | rs;
				bin = (bin << 5) | rt;
				for (i = 0; i < a; i++)
					if (strcmp(labels[i], label) == 0){
						immed = (addresses[i]-pc)/4;
						break;
					}
				immed = (immed & 0x0000FFFF);
				immed = (immed | 0x0000);
				bin = (bin << 16) | immed;
				printf("0x%08X\n", bin);		//print line contents
			}
		}	// i mean, it could be better
		else if ( strcmp(instr, "j") == 0){
			if ( sscanf(opands, "%s", label) == 1){
				op = getOpcode(instr);
				for (i = 0; i < a; i++)
					if (strcmp(labels[i], label) == 0)
						break;
				targaddr = addresses[i] >> 2;
				targaddr = (0x03FFFFFF & targaddr);
				bin = (op << 26) | targaddr;
				printf("0x%08X\n", bin);		//print line contents
			}
		}	// gg wp
		pc += 4;
	}

	/* Printing & error checking */

	// printf("%i", pc);
	// for(i = 0; i < a; i++){			// parse lines
	 //		if( lines[i] != NULL) 			// if element has data
	 //		printf("\n%s:\t%d", labels[i], addresses[i]);			// print the line
	// }

	return 0;

}