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simplify fallback widening multiplication

This commit is contained in:
Trevor Spiteri 2018-10-24 13:30:21 +02:00
parent 2cb5caf996
commit 49a83c4174
1 changed files with 31 additions and 20 deletions
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51
src/arith.rs
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@ -778,15 +778,14 @@ macro_rules! mul_div_fallback {
let lh_rl = lh.wrapping_mul(rl);
let ll_rh = ll.wrapping_mul(rh);
let lh_rh = lh.wrapping_mul(rh);
let col01 = ll_rl as <$Single as FallbackHelper>::Unsigned;
let (col12, carry_col3) = lh_rl.carrying_add(ll_rh);
let col23 = lh_rh;
let (col12_hi, col12_lo) = col12.hi_lo();
let col12_lo_up = col12_lo.shift_lo_up_unsigned();
let (ans01, carry_col2) = col01.carrying_add(col12_lo_up);
let carries = carry_col2 as $Single + carry_col3.shift_lo_up();
let ans23 = col23.wrapping_add(carries).wrapping_add(col12_hi);
let col01 = ll_rl as <$Single as FallbackHelper>::Unsigned;
let (col01_hi, col01_lo) = col01.hi_lo();
let partial_col12 = lh_rl + col01_hi as $Single;
let (col12, carry_col3) = partial_col12.carrying_add(ll_rh);
let (col12_hi, col12_lo) = col12.hi_lo();
let ans01 = col12_lo.shift_lo_up_unsigned() + col01_lo;
let ans23 = lh_rh + col12_hi + carry_col3.shift_lo_up();
ans23.combine_lo_then_shl(ans01, frac_bits)
}
}
@ -885,16 +884,20 @@ mod tests {
let frac = Frac::to_u32();
let a = 0x0003456789abcdef_0123456789abcdef_u128;
let b = 5;
let af = FixedU128::<Frac>::from_bits(a << frac);
let bf = FixedU128::<Frac>::from_bits(b << frac);
assert_eq!((af + bf).to_bits(), (a << frac) + (b << frac));
assert_eq!((af - bf).to_bits(), (a << frac) - (b << frac));
assert_eq!((af * bf).to_bits(), (a << frac) * b);
// assert_eq!((af / bf).to_bits(), (a << frac) / b);
assert_eq!((af & bf).to_bits(), (a << frac) & (b << frac));
assert_eq!((af | bf).to_bits(), (a << frac) | (b << frac));
assert_eq!((af ^ bf).to_bits(), (a << frac) ^ (b << frac));
assert_eq!((!af).to_bits(), !(a << frac));
for &(a, b) in &[(a, b), (b, a)] {
let af = FixedU128::<Frac>::from_bits(a << frac);
let bf = FixedU128::<Frac>::from_bits(b << frac);
assert_eq!((af + bf).to_bits(), (a << frac) + (b << frac));
if a > b {
assert_eq!((af - bf).to_bits(), (a << frac) - (b << frac));
}
assert_eq!((af * bf).to_bits(), (a << frac) * b);
// assert_eq!((af / bf).to_bits(), (a << frac) / b);
assert_eq!((af & bf).to_bits(), (a << frac) & (b << frac));
assert_eq!((af | bf).to_bits(), (a << frac) | (b << frac));
assert_eq!((af ^ bf).to_bits(), (a << frac) ^ (b << frac));
assert_eq!((!af).to_bits(), !(a << frac));
}
}
#[test]
@ -903,8 +906,16 @@ mod tests {
let frac = Frac::to_u32();
let a = 0x0003456789abcdef_0123456789abcdef_i128;
let b = 5;
for &pair in &[(a, b), (a, -b), (-a, b), (-a, -b)] {
let (a, b) = pair;
for &(a, b) in &[
(a, b),
(a, -b),
(-a, b),
(-a, -b),
(b, a),
(b, -a),
(-b, a),
(-b, -a),
] {
let af = FixedI128::<Frac>::from_bits(a << frac);
let bf = FixedI128::<Frac>::from_bits(b << frac);
assert_eq!((af + bf).to_bits(), (a << frac) + (b << frac));