Struct csx64::exec::fpu::FPU

pub struct FPU {
    pub vals: [F80; 8],
    pub control: Control,
    pub status: Status,
    pub tag: Tag,
}

The complete FPU unit.

FPU value registers are not exposed on their own because they have interactions among one another and other internal FPU state registers that would make the separation pointless.

Fields

vals: [F80; 8]

The physical value registers. These are exposed so that they can be used in external calculations, however care should be taken when mutating them directly, as this would not take into account the other registers.

control: Control

status: Status

tag: Tag

Implementations

impl FPU

pub fn new() -> Self

Creates a new FPU in the initialized state.

pub fn reset(&mut self)

Clears the fpu back to the initialized state.

pub fn clear_exceptions(&mut self)

Clears the exception bits from the status register.

pub fn st_to_physical(&self, st: u8) -> u8

Converts a stack-top (ST) relative index to a physical index. A physical index is needed to directly use the stored register values or get a specific value from the tag register. Note that this will change if the top field is changed in the status register.

pub fn set_st(&mut self, st: u8, val: F80)

Assigns a value to the specified ST register. Updates the tag register accordingly.

pub fn get_st(&self, st: u8) -> Option<F80>

Gets the value in the specified ST register. If the tag for that register is marked Empty, returns None.

pub fn free_st(&mut self, st: u8)

Frees the specified ST register. This sets its tag to empty, but does not modify the value register.

pub fn push(&mut self, val: F80) -> Result<(), ()>

Pushes a value onto the fpu stack. Updates the status and tag registers accordingly. Fails if the push location is non-empty, in which case this operation is no-op.

pub fn pop(&mut self) -> Result<(), ()>

Pops a value off the fpu stack. Updates the status and tag registers accordingly, but the (logically) removed value is not modified. Fails if the pop location is empty, in which case this operation is no-op.

Trait Implementations

impl Default for FPU

fn default() -> FPU

Returns the “default value” for a type.