// second iteration:
// - insert correct addresses for variables and jump-addresses
int Assembler::make_program()
{
if (debug > 0)
printf("\n[FUNCTION: make_program]\n");
if (debug > 1)
printf("\tinitialize %i bytes for program\n",length_of_code);
// create byte-array for program:
program = (uint8_t*)malloc(length_of_code);
memset(program, 0, length_of_code);
// initialize byte-counter:
int c = 0;
// iterate through preprogram:
for (list<Precode>::iterator pc_iterator = preprogram.begin(); pc_iterator != preprogram.end(); pc_iterator++)
{
if (debug > 1)
printf("STATUS: reading next precode\n");
// get current code:
uint8_t code = pc_iterator->code;
if (pc_iterator != preprogram.begin())
{
program[pc_iterator->address + length_of_header] = code;
c = pc_iterator->address + length_of_header + 1;
}
else
{
program[pc_iterator->address] = code;
c = pc_iterator->address+ 1;
}
if (debug > 1)
printf("VAR: code at byte %i: %i\n",pc_iterator->address,code);
//check if current command is command with parameters and add them to program:
int value, err = -1;
// case jump-label:
if (code == JMP || code == JGZ || code == JOF || code == JEZ || code == JNO)
{
if (debug > 1)
printf("CASE: jump - get address\n");
err = find_label_address(pc_iterator->param1, &value);
}
// case var-name:
if (code == LDA || code == LDB || code == STR || code == MOV)
{
if (debug > 1)
printf("CASE: variable - get address\n");
err = find_var_address(pc_iterator->param1, &value);
}
// case constant value:
if (code == LDC)
{
if (debug > 1)
printf("Case: constant value\n");
value = pc_iterator->val;
// set err to 0 to flag for parsing:
err = 0;
}
// if no error occured:
if (err == 0)
{
parse_int(value, &program[c]);
c += WORDSIZE;
}
else if (err != -1)
return 1;
err = -1;
// check if current command has second parameter, and add it to program:
// case MOV:
if (code == MOV)
{
if (debug > 1)
printf("Case: move - get second address\n");
err = find_var_address(pc_iterator->param2, &value);
}
//if no error occured:
if (err == 0)
{
parse_int(value, &program[c]);
c += WORDSIZE;
}
else if (err != -1)
return 1;
}
return 0;
}
/*** process_file
* This function is the main input file processing loop. It takes the instruction string in ASM and turns it into
* machine code. First, the op-code and corresponding funct are determined and then the register names are read in and processed.
* The offset and jsec values are determined using other functions.
***/
struct instruction* process_file(struct instruction *inst, FILE *input)
{
char string[BUFFER_SIZE];
//note that the current instruction address is tracked. this is for use with branching and jumps.
int op, r1, r2, r3, funct, offset, jsec, address=0x4000;
while(fscanf(input, "%s", string) != EOF)
{
if (check_for_label(string) == 1)
{
fscanf(input, "%s", string);
}
set_op_funct(&op, &funct, string);
if (op == 0) //add, sub, and, or, slt, sltu
{
fscanf(input, "%s", string);
r3 = get_reg(string);
fscanf(input, "%s", string);
r1 = get_reg(string);
fscanf(input, "%s", string);
r2 = get_reg(string);
offset = 0;
jsec = 0;
}
else if (op == 2) //j
{
r1 = 0;
r2 = 0;
r3 = 0;
offset = 0;
fscanf(input, "%s", string);
jsec = find_label_address(inst, strcat(string,":"));
}
else if (op == 4) //beq
{
fscanf(input, "%s", string);
r1 = get_reg(string);
fscanf(input, "%s", string);
r2 = get_reg(string);
r3 = 0;
fscanf(input, "%s", string);
offset = calculate_offset(address, find_label_address(inst, strcat(string,":")));
jsec = 0;
}
else if (op == 8) //addi
{
fscanf(input, "%s", string);
r1 = get_reg(string);
fscanf(input, "%s", string);
r2 = get_reg(string);
r3 = 0;
fscanf(input, "%d", &offset);
jsec = 0;
}
else if (op == 10 || op == 11) //slti, sltiu
{
fscanf(input, "%s", string);
r2 = get_reg(string);
fscanf(input, "%s", string);
r1 = get_reg(string);
r3 = 0;
fscanf(input, "%d", &offset);
jsec = 0;
}
else if (op == 15) //lui
{
fscanf(input, "%s", string);
r1 = 0;
r2 = get_reg(string);
r3 = 0;
fscanf(input, "%d", &offset);
jsec = 0;
}
else if (op == 35 || op == 43) //lw, sw
{
fscanf(input, "%s", string);
r2 = get_reg(string);
fscanf(input, "%s", string);
int offset, reg;
get_mem_offset_and_word_reg(string, &offset, ®);
r1 = reg;
r3 = 0;
offset = offset;
jsec = 0;
}
inst = modify_ll_node(inst, address, op, r1, r2, r3, funct, offset, jsec);
address += 0x4; //the current address is incremented by 4 after every instruction is processed
}
return inst;
}
