Binary coded decimal: Difference between revisions
Rust implementation
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992098765431 - 987654321 = 991111111110
991111111110 - 987654321 = 990123456789
</pre>
=={{header|Rust}}==
Based on the Forth implementation re: how to implement BCD arithmetic in software. Uses operator overloading for new BCD type.
<lang Rust>
#[derive(Copy, Clone)]
pub struct Bcd64 {
bits: u64
}
use std::ops::*;
impl Add for Bcd64 {
type Output = Self;
fn add(self, other: Self) -> Self {
let t1 = self.bits + 0x0666_6666_6666_6666;
let t2 = t1.wrapping_add(other.bits);
let t3 = t1 ^ other.bits;
let t4 = !(t2 ^ t3) & 0x1111_1111_1111_1110;
let t5 = (t4 >> 2) | (t4 >> 3);
return Bcd64{ bits: t2 - t5 };
}
}
impl Neg for Bcd64 {
type Output = Self;
fn neg(self) -> Self { // return 10's complement
let t1 = -(self.bits as i64) as u64;
let t2 = t1.wrapping_add(0xFFFF_FFFF_FFFF_FFFF);
let t3 = t2 ^ 1;
let t4 = !(t2 ^ t3) & 0x1111_1111_1111_1110;
let t5 = (t4 >> 2) | (t4 >> 3);
return Bcd64{ bits: t1 - t5 };
}
}
impl Sub for Bcd64 {
type Output = Self;
fn sub(self, other: Self) -> Self {
return self + -other;
}
}
#[test]
fn addition_test() {
let one = Bcd64{ bits: 0x01 };
assert_eq!((Bcd64{ bits: 0x19 } + one).bits, 0x20);
assert_eq!((Bcd64{ bits: 0x30 } - one).bits, 0x29);
assert_eq!((Bcd64{ bits: 0x99 } + one).bits, 0x100);
}
</lang>
{{Out}}
For the output, use "cargo test" to run the unit test for this module.
<pre>
running 1 test
test bcd::addition_test ... ok
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
</pre>
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