isa/checker.cpp


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#include <cassert>

#include "isa/checker.h"
#include "isa/isa.h"

void checker::execute() {
    assert(!halted);
    auto int_enable_delay = ctlregs[INT_ENABLE] >> 1;
    if (ctlregs[INT_ENABLE] & 1) {
        // check for interrupt
    }
    ctlregs[INT_ENABLE] = (int_enable_delay << 1) | int_enable_delay;
    inst = decode(ctlregs[DATA_INSTRUCTION_FIELD_BUFFER],
                  pc,
                  mem.fetch(pc));
    auto next_pc = inst.next_pc;
    if (inst.need_indirect_load) {
        auto addr = mem.fetch(inst.init_address.value());
        if (inst.need_autoinc_store)
            mem.store(*inst.init_address, (addr + 1) & 07777);
        inst.final_address = addr;
    } else {
        assert(!inst.need_autoinc_store);
    }
    if (inst.need_exec_load)
        inst.data = mem.fetch(inst.final_address.value());
    if (inst.need_read_acc)
        inst.acc = acc;
    if (inst.need_read_link)
        inst.link = link;
    if (inst.read_ctlreg.has_value())
        inst.ctlval = ctlregs[*inst.read_ctlreg];
    inst.execute();
    if (inst.need_write_acc)
        acc = inst.acc.value();
    if (inst.need_write_link)
        link = inst.link.value();
    if (inst.write_ctlreg.has_value())
        ctlregs[*inst.write_ctlreg] = inst.ctlval.value();
    if (inst.need_exec_store)
        mem.store(inst.final_address.value(), inst.data.value());
    assert(inst.next_pc == next_pc || inst.possibly_redirects);
    pc = inst.next_pc;
    halted = inst.halt;
}