133 lines
2.7 KiB
Rust
133 lines
2.7 KiB
Rust
//! Floating-point control and status register
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use bit_field::BitField;
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/// Floating-point control and status register
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#[derive(Clone, Copy, Debug)]
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pub struct FCSR {
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bits: u32,
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}
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/// Accrued Exception Flags
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#[derive(Clone, Copy, Debug)]
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pub struct Flags(u32);
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/// Accrued Exception Flag
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#[derive(Clone, Copy, Debug)]
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pub enum Flag {
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/// Inexact
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NX = 0b00001,
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/// Underflow
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UF = 0b00010,
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/// Overflow
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OF = 0b00100,
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/// Divide by Zero
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DZ = 0b01000,
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/// Invalid Operation
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NV = 0b10000,
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}
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impl Flags {
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/// Inexact
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#[inline]
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pub fn nx(&self) -> bool {
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self.0.get_bit(0)
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}
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/// Underflow
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#[inline]
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pub fn uf(&self) -> bool {
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self.0.get_bit(1)
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}
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/// Overflow
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#[inline]
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pub fn of(&self) -> bool {
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self.0.get_bit(2)
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}
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/// Divide by Zero
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#[inline]
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pub fn dz(&self) -> bool {
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self.0.get_bit(3)
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}
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/// Invalid Operation
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#[inline]
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pub fn nv(&self) -> bool {
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self.0.get_bit(4)
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}
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}
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/// Rounding Mode
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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pub enum RoundingMode {
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RoundToNearestEven = 0b000,
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RoundTowardsZero = 0b001,
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RoundDown = 0b010,
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RoundUp = 0b011,
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RoundToNearestMaxMagnitude = 0b100,
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Invalid = 0b111,
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}
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impl FCSR {
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/// Returns the contents of the register as raw bits
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pub fn bits(&self) -> u32 {
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self.bits
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}
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/// Accrued Exception Flags
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#[inline]
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pub fn fflags(&self) -> Flags {
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Flags(self.bits.get_bits(0..5))
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}
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/// Rounding Mode
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#[inline]
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pub fn frm(&self) -> RoundingMode {
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match self.bits.get_bits(5..8) {
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0b000 => RoundingMode::RoundToNearestEven,
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0b001 => RoundingMode::RoundTowardsZero,
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0b010 => RoundingMode::RoundDown,
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0b011 => RoundingMode::RoundUp,
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0b100 => RoundingMode::RoundToNearestMaxMagnitude,
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_ => RoundingMode::Invalid,
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}
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}
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}
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read_csr!(0x003, __read_fcsr);
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write_csr!(0x003, __write_fcsr);
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clear!(0x003, __clear_fcsr);
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/// Reads the CSR
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#[inline]
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pub fn read() -> FCSR {
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FCSR { bits: unsafe{ _read() as u32 } }
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}
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/// Writes the CSR
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#[inline]
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pub unsafe fn set_rounding_mode(frm: RoundingMode) {
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let old = read();
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let bits = ((frm as u32) << 5) | old.fflags().0;
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_write(bits as usize);
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}
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/// Resets `fflags` field bits
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#[inline]
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pub unsafe fn clear_flags() {
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let mask = 0b11111;
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_clear(mask);
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}
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/// Resets `fflags` field bit
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#[inline]
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pub unsafe fn clear_flag(flag: Flag) {
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_clear(flag as usize);
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}
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