/* Return resulting exception status */
static exc_t sim_step()
{
word_t aluA;
word_t aluB;
word_t alufun;
exc_t status = update_state(); /* Update state from last cycle */
if (plusmode) {
pc = gen_pc();
}
valp = pc;
if (get_byte_val(mem, valp, &instr)) {
icode = HI4(instr);
ifun = LO4(instr);
} else {
instr = HPACK(I_NOP,0);
icode = I_NOP;
ifun = 0;
status = EXC_ADDR;
sim_log("Couldn't fetch at address 0x%x\n", valp);
}
valp++;
if (gen_need_regids()) {
byte_t regids;
if (get_byte_val(mem, valp, ®ids)) {
ra = GET_RA(regids);
rb = GET_RB(regids);
} else {
ra = REG_NONE;
rb = REG_NONE;
status = EXC_ADDR;
sim_log("Couldn't fetch at address 0x%x\n", valp);
}
valp++;
} else {
ra = REG_NONE;
rb = REG_NONE;
}
if (gen_need_valC()) {
if (get_word_val(mem, valp, &valc)) {
} else {
valc = 0;
status = EXC_ADDR;
sim_log("Couldn't fetch at address 0x%x\n", valp);
}
valp+=4;
} else {
valc = 0;
}
if (status == EXC_NONE && !gen_instr_valid()) {
status = EXC_INSTR;
}
sim_log("IF: Fetched %s at 0x%x. ra=%s, rb=%s, valC = 0x%x\n",
iname(HPACK(icode,ifun)), pc, reg_name(ra), reg_name(rb), valc);
if (status == EXC_NONE && icode == I_HALT) {
status = EXC_HALT;
}
srcA = gen_srcA();
if (srcA != REG_NONE) {
vala = get_reg_val(reg, srcA);
} else {
vala = 0;
}
srcB = gen_srcB();
if (srcB != REG_NONE) {
valb = get_reg_val(reg, srcB);
} else {
valb = 0;
}
destE = gen_dstE();
destM = gen_dstM();
aluA = gen_aluA();
aluB = gen_aluB();
alufun = gen_alufun();
vale = compute_alu(alufun, aluA, aluB);
cc_in = cc;
if (gen_set_cc())
cc_in = compute_cc(alufun, aluA, aluB);
bcond = (icode == I_JMP) && take_branch(cc, ifun);
mem_addr = gen_mem_addr();
mem_data = gen_mem_data();
if (status == EXC_NONE && gen_mem_read()) {
if (!get_word_val(mem, mem_addr, &valm)) {
sim_log("Couldn't read at address 0x%x\n", mem_addr);
return EXC_ADDR;
}
} else
valm = 0;
mem_write = status == EXC_NONE && gen_mem_write();
if (plusmode) {
prev_icode_in = icode;
prev_ifun_in = ifun;
prev_valc_in = valc;
prev_valm_in = valm;
prev_valp_in = valp;
prev_bcond_in = bcond;
} else {
/* Update PC */
pc_in = gen_new_pc();
}
sim_report();
return status;
}
/* Return resulting status */
static byte_t sim_step()
{
word_t aluA;
word_t aluB;
word_t alufun;
status = STAT_AOK;
imem_error = dmem_error = FALSE;
update_state(); /* Update state from last cycle */
if (plusmode) {
pc = gen_pc();
}
valp = pc;
instr = HPACK(I_NOP, F_NONE);
imem_error = !get_byte_val(mem, valp, &instr);
if (imem_error) {
sim_log("Couldn't fetch at address 0x%x\n", valp);
}
imem_icode = HI4(instr);
imem_ifun = LO4(instr);
icode = gen_icode();
ifun = gen_ifun();
instr_valid = gen_instr_valid();
valp++;
if (gen_need_regids()) {
byte_t regids;
if (get_byte_val(mem, valp, ®ids)) {
ra = GET_RA(regids);
rb = GET_RB(regids);
} else {
ra = REG_NONE;
rb = REG_NONE;
status = STAT_ADR;
sim_log("Couldn't fetch at address 0x%x\n", valp);
}
valp++;
} else {
ra = REG_NONE;
rb = REG_NONE;
}
if (gen_need_valC()) {
if (get_word_val(mem, valp, &valc)) {
} else {
valc = 0;
status = STAT_ADR;
sim_log("Couldn't fetch at address 0x%x\n", valp);
}
valp+=4;
} else {
valc = 0;
}
sim_log("IF: Fetched %s at 0x%x. ra=%s, rb=%s, valC = 0x%x\n",
iname(HPACK(icode,ifun)), pc, reg_name(ra), reg_name(rb), valc);
if (status == STAT_AOK && icode == I_HALT) {
status = STAT_HLT;
}
srcA = gen_srcA();
if (srcA != REG_NONE) {
vala = get_reg_val(reg, srcA);
} else {
vala = 0;
}
srcB = gen_srcB();
if (srcB != REG_NONE) {
valb = get_reg_val(reg, srcB);
} else {
valb = 0;
}
cond = cond_holds(cc, ifun);
destE = gen_dstE();
destM = gen_dstM();
aluA = gen_aluA();
aluB = gen_aluB();
alufun = gen_alufun();
vale = compute_alu(alufun, aluA, aluB);
cc_in = cc;
if (gen_set_cc())
cc_in = compute_cc(alufun, aluA, aluB);
bcond = cond && (icode == I_JMP);
mem_addr = gen_mem_addr();
mem_data = gen_mem_data();
if (gen_mem_read()) {
dmem_error = dmem_error || !get_word_val(mem, mem_addr, &valm);
if (dmem_error) {
sim_log("Couldn't read at address 0x%x\n", mem_addr);
}
} else
valm = 0;
mem_write = gen_mem_write();
if (mem_write) {
/* Do a test read of the data memory to make sure address is OK */
word_t junk;
dmem_error = dmem_error || !get_word_val(mem, mem_addr, &junk);
}
status = gen_Stat();
if (plusmode) {
prev_icode_in = icode;
prev_ifun_in = ifun;
prev_valc_in = valc;
prev_valm_in = valm;
prev_valp_in = valp;
prev_bcond_in = bcond;
} else {
/* Update PC */
pc_in = gen_new_pc();
}
sim_report();
return status;
}