diff --git a/src/fileaccess.c b/src/fileio.c
similarity index 96%
rename from src/fileaccess.c
rename to src/fileio.c
index 14bf70d..45b25e8 100644
--- a/src/fileaccess.c
+++ b/src/fileio.c
@@ -37,6 +37,7 @@ int writeBinaryFile(word instrs[], char outputFile[]){
 
 //reads assembly file of "inputFile" name, and passes 
 //each line into a parser
+//TODO: allocate whole file in memory, line-by-line
 int readAssemblyFile(char inputFile[]) {
     if (!isValidFileFormat(filename, "s")){
         exit(EXIT_FAILURE);
diff --git a/src/parser.c b/src/parser.c
index 1c30fc3..9f5f526 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -14,7 +14,10 @@
 // - count operands and match type/values
 // - generate final a64inst and return
 
-char *tokeniseOperands(char* str, int operandCount, char *operands[]){
+//takes string of operands, and reference to operandcounter
+//takes input of result array
+//outputs array of operands
+void tokeniseOperands(char* str, int operandCount, char *operands[]){
     char *operandsDupe = strdup(str);
     int operandCount = 0;
     char *operand = strtok(operandsDupe, OPERAND_DELIMITER);
@@ -25,10 +28,10 @@ char *tokeniseOperands(char* str, int operandCount, char *operands[]){
         operand = strtok(NULL, OPERAND_DELIMITER);
         operands[operandCount] = operand;
     }
-    return(operands);
-
 }
 
+//takes inputted assembly line and returns a 
+//pointer to an abstract representation of the instruction
 a64inst_instruction *parser(char asmLine[]){
     a64inst_instruction *instr = malloc(sizeof(a64inst_instruction)); 
     if (instr == NULL){
@@ -36,6 +39,7 @@ a64inst_instruction *parser(char asmLine[]){
     }
 
     //"opcode operand1, {operand2}, ..."
+    //duplicated as strtok modifies the input string
     char *stringptr = strdup(asmLine);
 
     char *opcode = strtok(stringptr, " ");