Struct pir_8_emu::isa::GeneralPurposeRegister

pub struct GeneralPurposeRegister { /* fields omitted */ }

There are eight 8-bit General Purpose registers, each has an internal address for use within the CPU, instructions like MOVE and LOAD can use these addresses.

All the registers will start with an initial value of 0.

There are eight 8-bit General Purpose registers, each has an internal address for use within the CPU, instructions like MOVE and LOAD can use these addresses. The first five registers have some special functionality, as described, the last three have no special functionality. The last four registers can also be used with the stack.

Address	Letter	Description
000	F	Flag register (can also be used to get a zero value)
001	S	Output of the ALU - ALU operations will overwrite any value stored
010	X	Input to ALU (Only input for unary operations)
011	Y	Second input for ALU
100	A	Port number for PORT instruction
101	B
110	C
111	D

Flag register

The flag register can be be read and written to as a general purpose register, though keep in mind that ALU and Compare instructions can effect the value of the flags.

Not all of the bits have a specified role (yet), though the CLRF operation will still clear them.

A value of 1 denotes the flag as 'set', whilst a value of 0 denotes the flag is 'unset'.

Below is a description of what each bit in the flag register denotes.

Bit	Letter	Description
0	Z	Zero flag
1	C	Carry flag
2	P	Parity (even number of set bits)
3	E	Equals flag
4	G	Greater than
5
6
7

Methods

impl GeneralPurposeRegister

pub fn new(address: u8, letter: char) -> Option<GeneralPurposeRegister>

Create a new, empty register named as specified.

Examples

let x = GeneralPurposeRegister::new(0b010, 'X').unwrap();
assert_eq!(*x, 0);
assert_eq!(x.address(), 0b010);
assert_eq!(x.letter(), 'X');

assert_eq!(GeneralPurposeRegister::new(0b1000, 'Q'), None);

pub fn address(self) -> u8

The address for this register

Limited to 3 bits' width

pub fn letter(self) -> char

The letter/mnemonic for this register

E.g. "X"

pub fn relabel(&mut self, to_letter: char) -> Result<(), ()>

Change this register's letter to the specified one

Will return Err(()) if the letter isn't ASCII

impl GeneralPurposeRegister

pub fn defaults() -> GeneralPurposeRegisterBank

Get the default 8 GP registers specified in the ISA

pub fn from_letters(s: &str) -> Result<GeneralPurposeRegisterBank, i8>

Create a GP register bank from letters contained within the specified string

The string must be 8-ASCII-characters-long.

If it's shorter, Err(-1) is returned, if it's longer, Err(8) is returned, if character for register at address AAA is non-ASCII, Err(AAA) is returned,

Examples

assert_eq!(GeneralPurposeRegister::from_letters("FSXYABCD"), Ok(GeneralPurposeRegister::defaults()));

Trait Implementations

impl Clone for GeneralPurposeRegister

fn clone(&self) -> GeneralPurposeRegister

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for GeneralPurposeRegister

impl Debug for GeneralPurposeRegister

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Deref for GeneralPurposeRegister

type Target = u8

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl DerefMut for GeneralPurposeRegister

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl Display for GeneralPurposeRegister

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Eq for GeneralPurposeRegister

impl Hash for GeneralPurposeRegister

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].

impl Ord for GeneralPurposeRegister

fn cmp(&self, other: &GeneralPurposeRegister) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

🔬 This is a nightly-only experimental API. (clamp)

Restrict a value to a certain interval.

impl PartialEq<GeneralPurposeRegister> for GeneralPurposeRegister

fn eq(&self, other: &GeneralPurposeRegister) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &GeneralPurposeRegister) -> bool

This method tests for !=.

impl PartialOrd<GeneralPurposeRegister> for GeneralPurposeRegister

fn partial_cmp(&self, other: &GeneralPurposeRegister) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &GeneralPurposeRegister) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &GeneralPurposeRegister) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &GeneralPurposeRegister) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &GeneralPurposeRegister) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl ReadWritable for GeneralPurposeRegister

fn was_read(&self) -> bool

Check if this object was read from.

fn was_written(&self) -> bool

Check if this object was written to.

fn reset_rw(&mut self)

Reset the R/W marking of this object.

impl StructuralEq for GeneralPurposeRegister

impl StructuralPartialEq for GeneralPurposeRegister