fast-posit 0.2.0

Software implementation of the Posit floating point format
Documentation 
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use super::*;
use crate::Quire;

use core::fmt::Debug;

impl<
  const N: u32,
  const ES: u32,
  Int: crate::Int,
  const RS: u32,
> Debug for Posit<N, ES, Int, RS> {
  fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
    if const { Self::JUNK_BITS == 0 } {
      let bits = self.0;
      f.debug_tuple("Posit")
        .field(&format_args!("0b{bits:0w$b}", w=Int::BITS as usize))
        .finish()
    } else {
      let bits_junk = self.0.lshr(Self::BITS);
      let bits_significant = self.0.mask_lsb(Self::BITS);
      f.debug_tuple("Posit")
        .field(&format_args!("0b{bits_junk:0wj$b}_{bits_significant:0ws$b}", wj=Self::JUNK_BITS as usize, ws=Self::BITS as usize))
        .finish()
    }
  }
}

impl<
  const N: u32,
  const ES: u32,
  const RS: u32,
  Int: crate::Int,
> Debug for Decoded<N, ES, RS, Int> {
  fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
    let frac_hidden = self.frac.lshr(Self::FRAC_WIDTH);
    let frac_explicit = (self.frac << 2).lshr(3);
    let frac_round = self.frac & Int::ONE;
    if const { Self::ES != 0 } {
      let exp_regime = self.exp.lshr(ES);
      let exp_exponent = self.exp.mask_lsb(ES);
      let exp_total = self.exp;
      f.debug_struct("Decoded")
        .field("frac", &format_args!("0b{frac_hidden:02b}_{frac_explicit:0w$b}_{frac_round:b}",
          w=Int::BITS as usize - 3
        ))
        .field("exp", &format_args!("0b{exp_regime:0wr$b}_{exp_exponent:0we$b} ({exp_total:+})",
          wr=(Int::BITS - ES) as usize, we=ES as usize,
        ))
        .finish()
    } else {
      let exp_total = self.exp;
      f.debug_struct("Decoded")
        .field("frac", &format_args!("0b{frac_hidden:02b}_{frac_explicit:0w$b}_{frac_round:b}",
          w=Int::BITS as usize - 3
        ))
        .field("exp", &format_args!("0b{exp_total:0wr$b}_ ({exp_total:+})",
          wr=(Int::BITS - ES) as usize,
        ))
        .finish()
    }
  }
}

impl<
  const N: u32,
  const ES: u32,
  const SIZE: usize,
> Debug for Quire<N, ES, SIZE> {
  fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
    let mut handle = f.debug_tuple("Quire");
    for i in self.0 {
      handle.field(&format_args!("0x{i:02x}"));
    }
    handle.finish()
  }
}

#[cfg(test)]
#[allow(overflowing_literals)]
mod tests {
  use super::*;

  #[test]
  fn posit_nojunk() {
    assert_eq!(
      format!("{:?}", Posit::<8, 2, i8>::from_bits(0b00101011)).as_str(),
      "Posit(0b00101011)",
    );
    assert_eq!(
      format!("{:?}", Posit::<8, 2, i8>::from_bits(0b10101011)).as_str(),
      "Posit(0b10101011)",
    );
  }

  #[test]
  fn posit_junk() {
    assert_eq!(
      format!("{:?}", Posit::<6, 2, i16>::from_bits(0b001011)).as_str(),
      "Posit(0b0000000000_001011)",
    );
    assert_eq!(
      format!("{:?}", Posit::<6, 2, i16>::from_bits(0b101011)).as_str(),
      "Posit(0b1111111111_101011)",
    );
  }

  #[test]
  fn decoded() {
    assert_eq!(
      format!("{:?}", Decoded::<6, 2, 6, i16>{ frac: 0b01_0010101110110_0, exp: 3 }).as_str(),
      "Decoded { frac: 0b01_0010101110110_0, exp: 0b00000000000000_11 (+3) }",
    );
    assert_eq!(
      format!("{:?}", Decoded::<6, 2, 6, i16>{ frac: 0b10_1101010001010_0, exp: 3 }).as_str(),
      "Decoded { frac: 0b10_1101010001010_0, exp: 0b00000000000000_11 (+3) }",
    );
    assert_eq!(
      format!("{:?}", Decoded::<6, 2, 6, i16>{ frac: 0b01_0000000000000_1, exp: -1 }).as_str(),
      "Decoded { frac: 0b01_0000000000000_1, exp: 0b11111111111111_11 (-1) }",
    );
    assert_eq!(
      format!("{:?}", Decoded::<6, 4, 6, i16>{ frac: 0b01_0000000000000_1, exp: -20 }).as_str(),
      "Decoded { frac: 0b01_0000000000000_1, exp: 0b111111111110_1100 (-20) }",
    );
    assert_eq!(
      format!("{:?}", Decoded::<6, 0, 6, i16>{ frac: 0b01_0000000000000_1, exp: -20 }).as_str(),
      "Decoded { frac: 0b01_0000000000000_1, exp: 0b1111111111101100_ (-20) }",
    );
  }

  #[test]
  fn quire() {
    let bytes = [0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78];
    assert_eq!(
      format!("{:?}", crate::q8::from_le_bytes(bytes)).as_str(),
      "Quire(0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78, 0x12, 0x34, 0x56, 0x78)",
    );
  }
}