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use address::{Address, AddressDiff};
use memory::{STACK_ADDRESS_LO, STACK_ADDRESS_HI};
#[derive(Copy, Clone)]
pub struct StatusArgs {
pub negative: bool,
pub overflow: bool,
pub unused: bool,
pub brk: bool,
pub decimal_mode: bool,
pub disable_interrupts: bool,
pub zero: bool,
pub carry: bool,
}
impl StatusArgs {
pub fn none() -> StatusArgs {
StatusArgs {
negative: false,
overflow: false,
unused: false,
brk: false,
decimal_mode: false,
disable_interrupts: false,
zero: false,
carry: false,
}
}
}
bitflags! {
pub struct Status: u8 {
const PS_NEGATIVE = 0b1000_0000;
const PS_OVERFLOW = 0b0100_0000;
const PS_UNUSED = 0b0010_0000;
const PS_BRK = 0b0001_0000;
const PS_DECIMAL_MODE = 0b0000_1000;
const PS_DISABLE_INTERRUPTS = 0b0000_0100;
const PS_ZERO = 0b0000_0010;
const PS_CARRY = 0b0000_0001;
}
}
impl Status {
pub fn default() -> Status {
Status::new(StatusArgs {
negative: false,
overflow: false,
unused: true,
brk: false,
decimal_mode: false,
disable_interrupts: true,
zero: false,
carry: false,
})
}
pub fn new(StatusArgs { negative,
overflow,
unused,
brk,
decimal_mode,
disable_interrupts,
zero,
carry }: StatusArgs) -> Status
{
let mut out = Status::empty();
if negative {
out |= Status::PS_NEGATIVE
}
if overflow {
out |= Status::PS_OVERFLOW
}
if unused {
out |= Status::PS_UNUSED
}
if brk {
out |= Status::PS_BRK
}
if decimal_mode {
out |= Status::PS_DECIMAL_MODE
}
if disable_interrupts {
out |= Status::PS_DISABLE_INTERRUPTS
}
if zero {
out |= Status::PS_ZERO
}
if carry {
out |= Status::PS_CARRY
}
out
}
pub fn and(&mut self, rhs: Status) {
*self &= rhs;
}
pub fn or(&mut self, rhs: Status) {
*self |= rhs;
}
pub fn set_with_mask(&mut self, mask: Status, rhs: Status) {
*self = (*self & !mask) | rhs;
}
}
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
pub struct StackPointer(pub u8);
impl StackPointer {
pub fn to_address(self) -> Address {
STACK_ADDRESS_LO + AddressDiff(i32::from(self.0))
}
pub fn decrement(&mut self) {
self.0 -= 1;
}
pub fn increment(&mut self) {
self.0 += 1;
}
}
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub struct Registers {
pub accumulator: i8,
pub index_x: i8,
pub index_y: i8,
pub stack_pointer: StackPointer,
pub program_counter: Address,
pub status: Status,
}
impl Registers {
pub fn new() -> Registers {
Registers {
accumulator: 0,
index_x: 0,
index_y: 0,
stack_pointer: StackPointer(STACK_ADDRESS_HI.get_offset()),
program_counter: Address(0),
status: Status::default(),
}
}
}