diff --git a/Makefile b/Makefile
index 9ccf36f..8ce2e57 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,8 @@
 FILES = *.c */*.c
-INCLUDES = -I. -I./parser/ -I./compiler -I./vm -I./tokenizer
+LIBRARIES = -lpthread
+INCLUDES = -I. -I./parser/ -I./compiler/ -I./vm/ -I./tokenizer/
 CFLAGS = -std=c99 -g
 OUTFILE = jack-compiler
 
 main: ${FILES}
-	${CC} ${CFLAGS} ${INCLUDES} -o ${OUTFILE} ${FILES}
+	${CC} ${CFLAGS} ${LIBRARIES} ${INCLUDES} -o ${OUTFILE} ${FILES}
diff --git a/compiler/compiler.c b/compiler/compiler.c
index f4c50ae..dd21c0c 100644
--- a/compiler/compiler.c
+++ b/compiler/compiler.c
@@ -391,16 +391,6 @@ LINEBLOCK* compileclass(COMPILER* c, CLASS* class) {
 	return output;
 }
 
-void compile(COMPILER* c) {
-	LINEBLOCK* output = NULL;
-	CLASS* curr = c->classes;
-	while(curr != NULL) {
-		output = mergelnblks(output, compileclass(c, curr));
-		curr = curr->next;
-	}
-	c->output = output;
-}
-
 COMPILER* mkcompiler(CLASS* classes) {
 	COMPILER* c = (COMPILER*)malloc(sizeof(COMPILER));
 	c->globalscope = mkscope(NULL);
diff --git a/compiler/compiler.h b/compiler/compiler.h
index f9819e2..cbff6c5 100644
--- a/compiler/compiler.h
+++ b/compiler/compiler.h
@@ -7,10 +7,8 @@
 typedef struct {
 	CLASS* classes;
 	SCOPE* globalscope;
-	LINEBLOCK* output;
 } COMPILER;
 
 COMPILER* mkcompiler(CLASS* classes);
-void compile(COMPILER* c);
-
+LINEBLOCK* compileclass(COMPILER* c, CLASS* class);
 #endif
diff --git a/io.c b/io.c
new file mode 100644
index 0000000..ee22f28
--- /dev/null
+++ b/io.c
@@ -0,0 +1,177 @@
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include "util.h"
+#include "io.h"
+
+#include <limits.h>
+#ifndef PATH_MAX
+#ifdef __linux__
+#include <linux/limits.h>
+#else
+#define PATH_MAX 512
+#endif
+#endif
+
+char* strtail(char* str, int len, int count) {
+	int index = len - count;
+	if (index <= 0) return str;
+	return str + (sizeof(char) * (index));
+}
+
+char* strhead(char* str, int count) {
+	return str + (sizeof(char) * count);
+}
+
+char* trimstr(char* str, int len, int end) {
+	int count = len - end;
+	char oldchar = str[count];
+	str[count] = '\0';
+	char* newstr = (char*)malloc(sizeof(char) * (1 + count));
+	strcpy(newstr, str);
+	str[count] = oldchar;
+	return newstr;
+}
+
+char* getname(char* f, int len) {
+	int startind = 0;
+	int endind = len - 1;
+	bool readsmt = false;
+ 
+	for(int i = endind; i >= 0; i--) {
+		if(f[i] == '/') {
+			if(!readsmt) {
+				endind = i-1;
+				f[i] = '\0';
+				continue;
+			}
+			startind = i+1;
+			break;
+		}
+		if(f[i] == '.')
+			endind = i-1;
+		readsmt = true;
+	}
+
+	int sz = sizeof(char)*(endind - startind + 2);
+	char* startstr = strhead(f, startind);
+	char* retstr = (char*)malloc(sz);
+	snprintf(retstr, sz, "%s", startstr);
+	return retstr;
+}
+
+char* getfullname(char* fname, char* dirname, int dirlen) {
+	int fnamelen = strlen(fname);
+	int sz = sizeof(char)*(fnamelen+dirlen+2);
+	char* fullname = (char*)malloc(sz);
+	sprintf(fullname, "%s/%s", dirname, fname);
+	return fullname;
+}
+
+bool isdotjack(char* f, int len) {
+	const char* ext = ".jack";
+	return strcmp(strtail(f, len, strlen(ext)), ext) == 0;
+}
+
+bool isdir(char* f, int len) {
+	bool readsmt = false;
+	for(int i = len-1; i >= 0; i--) {
+		if(f[i] == '.')
+			if(readsmt)
+				return false;
+			else
+				continue;
+		if(f[i] == '/')
+			return 1;
+		readsmt = true;
+	}
+	return true;
+}
+
+char* getoutname(char* fullname, int len) {
+	char* trimmed = trimstr(fullname, len, 4);
+	int sz = sizeof(char) * (len-1);
+	char* outname = (char*)malloc(sz);
+	sprintf(outname, "%svm", trimmed);
+	return outname;
+}
+
+FILELIST* addfile(FILELIST* l, char* fullname, char* name) {
+	FILELIST* new = (FILELIST*)malloc(sizeof(FILELIST));
+	new->name = name;
+	new->fullname = fullname;
+	new->next = l;
+	new->outname = getoutname(fullname, strlen(fullname));
+	return new;
+}
+
+FILELIST* getfilesfromdir(char* dir) {
+	FILELIST* filelist = NULL;
+	DIR* d = opendir(dir);
+
+	if(d == NULL) {
+		eprintf("Error while opening directory '%s': %s\n", dir, strerror(errno));
+		exit(errno);
+	}
+
+	int len = strlen(dir);
+	struct dirent* thisfile;
+	while(thisfile = readdir(d), thisfile != NULL) {
+		if(isdotjack(thisfile->d_name, strlen(thisfile->d_name))) {
+			char* fullname = getfullname(thisfile->d_name, dir, len);
+			char* name = getname(thisfile->d_name, len);
+			filelist = addfile(filelist, fullname, name);
+		}
+	}
+	
+	closedir(d);
+
+	if(filelist == NULL) {
+		eprintf("Directory '%s' doesn't have any .jack file\n", dir);
+		exit(1);
+	}
+	return filelist;
+}
+
+FILELIST* getsinglefile(char* file) {
+	int len = strlen(file);
+	if(isdotjack(file, len)){
+		char* name = getname(file, len);
+		char* fullname = heapstr(file, len);
+
+		FILE* input = fopen(fullname, "r");
+		if(input == NULL) {
+			eprintf("Error while reading file '%s': %s\n", file, strerror(errno));
+			exit(errno);
+		}
+		fclose(input);
+
+		return addfile(NULL, fullname, name);
+	}
+	else {
+		eprintf("Input file must be named like 'Xxx.vm'\n");
+		exit(1);
+	}
+}
+
+FILELIST* getfiles(char* input) {
+	int inplen = strlen(input);
+	bool isitdir = isdir(input, inplen);
+
+	if(isitdir)
+		return getfilesfromdir(input);
+	else
+		return getsinglefile(input);
+}
+
+void freefilelist(FILELIST* fs) {
+	free(fs->name);
+	free(fs->fullname);
+	if(fs->next != NULL)
+		freefilelist(fs->next);
+}
diff --git a/io.h b/io.h
new file mode 100644
index 0000000..1e493b3
--- /dev/null
+++ b/io.h
@@ -0,0 +1,14 @@
+#ifndef IO_H
+#define IO_H
+
+typedef struct flist {
+	char* name;
+	char* fullname;
+	char* outname;
+	struct flist* next;
+} FILELIST;
+
+
+FILELIST* getfiles(char* input);
+void freefilelist(FILELIST* fs);
+#endif
diff --git a/main.c b/main.c
index 78dd57c..e892bd7 100644
--- a/main.c
+++ b/main.c
@@ -2,31 +2,126 @@
 #include <errno.h>
 #include <string.h>
 #include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
 #include "parser.h"
 #include "compiler.h"
+#include "io.h"
 
-void printcompiler(COMPILER* c) {
-	printlns(c->output->head, stdout);
+typedef struct unit {
+	FILELIST* file;
+	TOKEN* tokens;
+	CLASS* parsed;
+	COMPILER* compiler;
+	LINEBLOCK* compiled;
+	struct unit* next;
+} COMPILEUNIT;
+
+void* parseunit(void* input) {
+	COMPILEUNIT* unit = (COMPILEUNIT*)input;
+
+	unit->parsed = parse(unit->tokens, unit->file->name);
+
+	pthread_exit(NULL);
+}
+
+void* compileunit(void* input) {
+	COMPILEUNIT* unit = (COMPILEUNIT*)input;
+
+	unit->compiled = compileclass(unit->compiler, unit->parsed);
+
+	pthread_exit(NULL);
+}
+
+void waitthreads(pthread_t* threads, int amount) {
+	void* status;
+	int code;
+	for(int i = 0; i < amount; i++) {
+		code = pthread_join(threads[i], &status);
+		if(code) {
+			eprintf("Error while joining thread %i: %s\n", i, strerror(code));
+			exit(code);
+		}
+	}
+}
+
+void actonunits(COMPILEUNIT* units, void*(*fun)(void*)) {
+	pthread_t mythreads[_SC_THREAD_THREADS_MAX];
+	pthread_attr_t attr;
+	pthread_attr_init(&attr);
+	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+
+	COMPILEUNIT* curr = units;
+
+	int i;
+	int code;
+	do {
+		i = 0;
+		while(curr != NULL && i < _SC_THREAD_THREADS_MAX) {
+			code = pthread_create(&mythreads[i], NULL, fun, curr);
+
+			if(code) {
+				eprintf("Error while creating thread %i: %s\n", i, strerror(code));
+				exit(code);
+			}
+
+			curr = curr->next;
+			i++;
+		}
+		waitthreads(mythreads, i);
+	} while(i == _SC_THREAD_THREADS_MAX);
+
+	pthread_attr_destroy(&attr);
 }
 
 int main(int argc, char* argv[]) {
+
 	if(argc < 2) {
-		fprintf(stderr, "Usage: %s {input file}\n", argv[0]);
+		eprintf("Usage: %s {input file(s)}\n", argv[0]);
 		return 1;
 	}
 
-	FILE* input = fopen(argv[1], "r");
+	FILELIST* files = getfiles(argv[1]);
+	FILELIST* curr = files->next;
 
-	if(input == NULL) {
-		fprintf(stderr, "%s\n", strerror(errno));
-		return errno;
+	COMPILEUNIT* head = (COMPILEUNIT*)malloc(sizeof(COMPILEUNIT));
+
+	head->file = files;
+	head->tokens = tokenize(files->fullname);
+
+	COMPILEUNIT* currunit = head;
+	while(curr != NULL) {
+		COMPILEUNIT* newunit = (COMPILEUNIT*)malloc(sizeof(COMPILEUNIT));
+		newunit->file = curr;
+		newunit->tokens = tokenize(curr->fullname);
+		currunit->next = newunit;
+		currunit = newunit;
+		curr = curr->next;
+	}
+	currunit->next = NULL;
+
+	actonunits(head, parseunit);
+
+	CLASS* headclass = head->parsed;
+	CLASS* currclass = headclass;
+	currunit = head->next;
+	while(currunit != NULL) {
+		currclass->next = currunit->parsed;
+		currclass = currunit->parsed;
+		currunit = currunit->next;
+	}
+	currclass->next = NULL;
+	COMPILER* compiler = mkcompiler(headclass);
+
+	currunit = head;
+	while(currunit != NULL) {
+		currunit->compiler = compiler;
+		currunit = currunit->next;
 	}
 
-	PARSER* p = mkparser(tokenize(input), argv[1]);
-	parse(p);
-	COMPILER* c = mkcompiler(p->output);
-	compile(c);
-	printcompiler(c);
-	
+	actonunits(head, compileunit);
+
+	printlns(head->compiled->head, stdout);
+
 	return 0;
 }
diff --git a/parser/parser-structure.c b/parser/parser-structure.c
index 6dff980..08ba8bf 100644
--- a/parser/parser-structure.c
+++ b/parser/parser-structure.c
@@ -43,19 +43,11 @@ CLASS* parseclass(PARSER* p) {
 	class->subroutdecs = parsesubroutdecs(p);
 
 	checkcontent(p, "}");
-	return class;
-}
 
-CLASS* parseclasses(PARSER* p) {
-	CLASS* head = parseclass(p);
-	CLASS* curr = head;
-	while(p->current != NULL && equals(p, "class")) {
-		curr->next = parseclass(p);
-		curr = curr->next;
-	}
-	if(curr != NULL)
-		curr->next = NULL;
-	return head;
+	if(p->current != NULL)
+		unexpected(p);
+
+	return class;
 }
 
 int parsepossibilities(PARSER* p, STRINGARRAY* poss) {
diff --git a/parser/parser-structure.h b/parser/parser-structure.h
index 8c1cf34..0b66485 100644
--- a/parser/parser-structure.h
+++ b/parser/parser-structure.h
@@ -1,5 +1,5 @@
 #ifndef PARSER_STRUCTURE_H
 #define PARSER_STRUCTURE_H
 #include "parser.h"
-CLASS* parseclasses(PARSER* p);
+CLASS* parseclass(PARSER* p);
 #endif
diff --git a/parser/parser.c b/parser/parser.c
index dfd6187..732ccfe 100644
--- a/parser/parser.c
+++ b/parser/parser.c
@@ -5,15 +5,10 @@
 #include "parser.h"
 #include "parser-structure.h"
 
-// Statements
-PARSER* mkparser(TOKEN* tokens, char* file) {
+CLASS* parse(TOKEN* tokens, char* file) {
 	PARSER* parser = (PARSER*)malloc(sizeof(PARSER));
 	parser->tokens = tokens;
 	parser->current = tokens;
 	parser->file = file;
-	return parser;
-}
-
-void parse(PARSER* p) {
-	p->output = parseclasses(p);
+	return parseclass(parser);
 }
diff --git a/parser/parser.h b/parser/parser.h
index d4f27b4..bbd341a 100644
--- a/parser/parser.h
+++ b/parser/parser.h
@@ -8,9 +8,7 @@ typedef struct {
 	TOKEN* current;
 	TOKEN* checkpoint;
 	char* file;
-	CLASS* output;
 } PARSER;
 
-PARSER* mkparser(TOKEN* tokens, char* file);
-void parse(PARSER* p);
+CLASS* parse(TOKEN* tokens, char* file);
 #endif
diff --git a/tokenizer/tokenizer.c b/tokenizer/tokenizer.c
index 7c8ce89..cf14b4e 100644
--- a/tokenizer/tokenizer.c
+++ b/tokenizer/tokenizer.c
@@ -23,7 +23,7 @@ void freestr(STRING* str);
 
 // Token manipulation;
 TOKEN* appendtokenraw(TOKEN* curitem, STRING* token, int definedat, TOKENTYPE type);
-TOKEN* appendtoken(TOKEN* curitem, STRING* token, int definedat);
+TOKEN* appendtoken(TOKEN* curitem, STRING* token, char* file, int definedat);
 #define mktoken() (TOKEN*)malloc(sizeof(TOKEN))
 
 // Char types
@@ -33,7 +33,7 @@ bool issymbol(STRING* tk);
 bool isint(char* str);
 bool isintcons(STRING* tk);
 bool isidentifier(STRING* tk);
-TOKENTYPE gettokentype(STRING* tk, int definedat);
+TOKENTYPE gettokentype(STRING* tk, char* file, int definedat);
 
 // Stream handling
 void skipln(FILE* input);
@@ -78,9 +78,9 @@ TOKEN* appendtokenraw(TOKEN* curitem, STRING* token, int definedat, TOKENTYPE ty
 	return nextitem;
 }
 
-TOKEN* appendtoken(TOKEN* curitem, STRING* token, int definedat) {
+TOKEN* appendtoken(TOKEN* curitem, STRING* token, char* file, int definedat) {
 	append(token, '\0');
-	return appendtokenraw(curitem, token, definedat, gettokentype(token, definedat));
+	return appendtokenraw(curitem, token, definedat, gettokentype(token, file, definedat));
 }
 
 // Char types
@@ -128,12 +128,12 @@ bool isidentifier(STRING* tk) {
 	return true;
 }
 
-TOKENTYPE gettokentype(STRING* tk, int definedat) {
+TOKENTYPE gettokentype(STRING* tk, char* file, int definedat) {
 	if(iskeyword(tk)) return keyword;
 	if(issymbol(tk)) return symbol;
 	if(isintcons(tk)) return integer;
 	if(isidentifier(tk)) return identifier;
-	eprintf("Unexpected token '%s'; line %i\n", tk->str, definedat);
+	eprintf("Unexpected token '%s'; file '%s', line %i\n", tk->str, file, definedat);
 	exit(1);
 }
 
@@ -188,7 +188,7 @@ void readstr(FILE* input, STRING* tmp, int definedat) {
 	append(tmp, '\0');
 }
 
-TOKEN* tokenize(FILE* input) {
+TOKEN* tokenize(char* file) {
 	TOKEN* head = mktoken();
 	TOKEN* lastitem = head;
 	TOKEN* curitem = head;
@@ -198,6 +198,7 @@ TOKEN* tokenize(FILE* input) {
 	CHARTYPE curtype;
 
 	int lnscount = 1;
+	FILE* input = fopen(file, "r");
 	
 	unsigned char c;
 	while(c = fgetc(input), !feof(input)) {
@@ -208,7 +209,7 @@ TOKEN* tokenize(FILE* input) {
 			continue;
 		else if(c == '"') {
 			if(lasttype != space)
-				curitem = appendtoken(curitem, tmptoken, lnscount);
+				curitem = appendtoken(curitem, tmptoken, file, lnscount);
 			readstr(input, tmptoken, lnscount);
 			lastitem = curitem;
 			curitem = appendtokenraw(curitem, tmptoken, lnscount, string);
@@ -221,13 +222,13 @@ TOKEN* tokenize(FILE* input) {
 		if(curtype == common) {
 			if(lasttype == charsymbol) {
 				lastitem = curitem;
-				curitem = appendtoken(curitem, tmptoken, lnscount);
+				curitem = appendtoken(curitem, tmptoken, file, lnscount);
 			}
 			append(tmptoken, c);
 		} else {
 			if(lasttype != space){
 				lastitem = curitem;
-				curitem = appendtoken(curitem, tmptoken, lnscount);
+				curitem = appendtoken(curitem, tmptoken, file, lnscount);
 			}
 			if(curtype == charsymbol)
 				append(tmptoken, c);
diff --git a/tokenizer/tokenizer.h b/tokenizer/tokenizer.h
index 5c4cda6..d3b47c6 100644
--- a/tokenizer/tokenizer.h
+++ b/tokenizer/tokenizer.h
@@ -16,6 +16,6 @@ typedef struct token {
 	struct token* next;
 } TOKEN;
 
-TOKEN* tokenize(FILE* input);
+TOKEN* tokenize(char* filename);
 void freetokenlist(TOKEN* list);
 #endif