use core::fmt::{self, Debug};
use crate::common::{is_8digits_le, parse_digits, ByteSlice};
#[derive(Clone)]
pub struct Decimal {
pub num_digits: usize,
pub decimal_point: i32,
pub negative: bool,
pub truncated: bool,
pub digits: [u8; Self::MAX_DIGITS],
}
impl Debug for Decimal {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("Decimal")
.field("num_digits", &self.num_digits)
.field("decimal_point", &self.decimal_point)
.field("negative", &self.negative)
.field("truncated", &self.truncated)
.field("digits", &(&self.digits[..self.num_digits]))
.finish()
}
}
impl PartialEq for Decimal {
fn eq(&self, other: &Self) -> bool {
self.num_digits == other.num_digits
&& self.decimal_point == other.decimal_point
&& self.negative == other.negative
&& self.truncated == other.truncated
&& self.digits[..] == other.digits[..]
}
}
impl Eq for Decimal {}
impl Default for Decimal {
fn default() -> Self {
Self {
num_digits: 0,
decimal_point: 0,
negative: false,
truncated: false,
digits: [0; Self::MAX_DIGITS],
}
}
}
impl Decimal {
pub const MAX_DIGITS: usize = 768;
pub const MAX_DIGITS_WITHOUT_OVERFLOW: usize = 19;
pub const DECIMAL_POINT_RANGE: i32 = 2047;
#[inline]
pub fn try_add_digit(&mut self, digit: u8) {
if self.num_digits < Self::MAX_DIGITS {
self.digits[self.num_digits] = digit;
}
self.num_digits += 1;
}
#[inline]
pub fn trim(&mut self) {
while self.num_digits != 0 && self.digits[self.num_digits - 1] == 0 {
self.num_digits -= 1;
}
}
#[inline]
pub fn round(&self) -> u64 {
if self.num_digits == 0 || self.decimal_point < 0 {
return 0;
} else if self.decimal_point > 18 {
return 0xFFFF_FFFF_FFFF_FFFF_u64;
}
let dp = self.decimal_point as usize;
let mut n = 0_u64;
for i in 0..dp {
n *= 10;
if i < self.num_digits {
n += self.digits[i] as u64;
}
}
let mut round_up = false;
if dp < self.num_digits {
round_up = self.digits[dp] >= 5;
if self.digits[dp] == 5 && dp + 1 == self.num_digits {
round_up = self.truncated || ((dp != 0) && (1 & self.digits[dp - 1] != 0))
}
}
if round_up {
n += 1;
}
n
}
#[inline]
pub fn left_shift(&mut self, shift: usize) {
if self.num_digits == 0 {
return;
}
let num_new_digits = number_of_digits_decimal_left_shift(self, shift);
let mut read_index = self.num_digits;
let mut write_index = self.num_digits + num_new_digits;
let mut n = 0_u64;
while read_index != 0 {
read_index -= 1;
write_index -= 1;
n += (self.digits[read_index] as u64) << shift;
let quotient = n / 10;
let remainder = n - (10 * quotient);
if write_index < Self::MAX_DIGITS {
self.digits[write_index] = remainder as u8;
} else if remainder > 0 {
self.truncated = true;
}
n = quotient;
}
while n > 0 {
write_index -= 1;
let quotient = n / 10;
let remainder = n - (10 * quotient);
if write_index < Self::MAX_DIGITS {
self.digits[write_index] = remainder as u8;
} else if remainder > 0 {
self.truncated = true;
}
n = quotient;
}
self.num_digits += num_new_digits;
if self.num_digits > Self::MAX_DIGITS {
self.num_digits = Self::MAX_DIGITS;
}
self.decimal_point += num_new_digits as i32;
self.trim();
}
#[inline]
pub fn right_shift(&mut self, shift: usize) {
let mut read_index = 0;
let mut write_index = 0;
let mut n = 0_u64;
while (n >> shift) == 0 {
if read_index < self.num_digits {
n = (10 * n) + self.digits[read_index] as u64;
read_index += 1;
} else if n == 0 {
return;
} else {
while (n >> shift) == 0 {
n *= 10;
read_index += 1;
}
break;
}
}
self.decimal_point -= read_index as i32 - 1;
if self.decimal_point < -Self::DECIMAL_POINT_RANGE {
self.num_digits = 0;
self.decimal_point = 0;
self.negative = false;
self.truncated = false;
return;
}
let mask = (1_u64 << shift) - 1;
while read_index < self.num_digits {
let new_digit = (n >> shift) as u8;
n = (10 * (n & mask)) + self.digits[read_index] as u64;
read_index += 1;
self.digits[write_index] = new_digit;
write_index += 1;
}
while n > 0 {
let new_digit = (n >> shift) as u8;
n = 10 * (n & mask);
if write_index < Self::MAX_DIGITS {
self.digits[write_index] = new_digit;
write_index += 1;
} else if new_digit > 0 {
self.truncated = true;
}
}
self.num_digits = write_index;
self.trim();
}
}
#[inline]
pub fn parse_decimal(mut s: &[u8]) -> Decimal {
let mut d = Decimal::default();
let start = s;
let c = s.get_first();
d.negative = c == b'-';
if c == b'-' || c == b'+' {
s = s.advance(1);
}
s = s.skip_chars(b'0');
parse_digits(&mut s, |digit| d.try_add_digit(digit));
if s.check_first(b'.') {
s = s.advance(1);
let first = s;
if d.num_digits == 0 {
s = s.skip_chars(b'0');
}
if cfg!(target_endian = "little") {
while s.len() >= 8 && d.num_digits + 8 < Decimal::MAX_DIGITS {
let v = s.read_u64();
if !is_8digits_le(v) {
break;
}
d.digits[d.num_digits..].write_u64(v - 0x3030_3030_3030_3030);
d.num_digits += 8;
s = s.advance(8);
}
}
parse_digits(&mut s, |digit| d.try_add_digit(digit));
d.decimal_point = s.len() as i32 - first.len() as i32;
}
if d.num_digits != 0 {
let mut n_trailing_zeros = 0;
for &c in start[..(start.len() - s.len())].iter().rev() {
if c == b'0' {
n_trailing_zeros += 1;
} else if c != b'.' {
break;
}
}
d.decimal_point += n_trailing_zeros as i32;
d.num_digits -= n_trailing_zeros;
d.decimal_point += d.num_digits as i32;
if d.num_digits > Decimal::MAX_DIGITS {
d.truncated = true;
d.num_digits = Decimal::MAX_DIGITS;
}
}
if s.check_first2(b'e', b'E') {
s = s.advance(1);
let mut neg_exp = false;
if s.check_first(b'-') {
neg_exp = true;
s = s.advance(1);
} else if s.check_first(b'+') {
s = s.advance(1);
}
let mut exp_num = 0_i32;
parse_digits(&mut s, |digit| {
if exp_num < 0x10000 {
exp_num = 10 * exp_num + digit as i32;
}
});
d.decimal_point += if neg_exp { -exp_num } else { exp_num };
}
for i in d.num_digits..Decimal::MAX_DIGITS_WITHOUT_OVERFLOW {
d.digits[i] = 0;
}
d
}
#[inline]
fn number_of_digits_decimal_left_shift(d: &Decimal, mut shift: usize) -> usize {
const TABLE: [u16; 65] = [
0x0000, 0x0800, 0x0801, 0x0803, 0x1006, 0x1009, 0x100D, 0x1812, 0x1817, 0x181D, 0x2024,
0x202B, 0x2033, 0x203C, 0x2846, 0x2850, 0x285B, 0x3067, 0x3073, 0x3080, 0x388E, 0x389C,
0x38AB, 0x38BB, 0x40CC, 0x40DD, 0x40EF, 0x4902, 0x4915, 0x4929, 0x513E, 0x5153, 0x5169,
0x5180, 0x5998, 0x59B0, 0x59C9, 0x61E3, 0x61FD, 0x6218, 0x6A34, 0x6A50, 0x6A6D, 0x6A8B,
0x72AA, 0x72C9, 0x72E9, 0x7B0A, 0x7B2B, 0x7B4D, 0x8370, 0x8393, 0x83B7, 0x83DC, 0x8C02,
0x8C28, 0x8C4F, 0x9477, 0x949F, 0x94C8, 0x9CF2, 0x051C, 0x051C, 0x051C, 0x051C,
];
const TABLE_POW5: [u8; 0x051C] = [
5, 2, 5, 1, 2, 5, 6, 2, 5, 3, 1, 2, 5, 1, 5, 6, 2, 5, 7, 8, 1, 2, 5, 3, 9, 0, 6, 2, 5, 1,
9, 5, 3, 1, 2, 5, 9, 7, 6, 5, 6, 2, 5, 4, 8, 8, 2, 8, 1, 2, 5, 2, 4, 4, 1, 4, 0, 6, 2, 5,
1, 2, 2, 0, 7, 0, 3, 1, 2, 5, 6, 1, 0, 3, 5, 1, 5, 6, 2, 5, 3, 0, 5, 1, 7, 5, 7, 8, 1, 2,
5, 1, 5, 2, 5, 8, 7, 8, 9, 0, 6, 2, 5, 7, 6, 2, 9, 3, 9, 4, 5, 3, 1, 2, 5, 3, 8, 1, 4, 6,
9, 7, 2, 6, 5, 6, 2, 5, 1, 9, 0, 7, 3, 4, 8, 6, 3, 2, 8, 1, 2, 5, 9, 5, 3, 6, 7, 4, 3, 1,
6, 4, 0, 6, 2, 5, 4, 7, 6, 8, 3, 7, 1, 5, 8, 2, 0, 3, 1, 2, 5, 2, 3, 8, 4, 1, 8, 5, 7, 9,
1, 0, 1, 5, 6, 2, 5, 1, 1, 9, 2, 0, 9, 2, 8, 9, 5, 5, 0, 7, 8, 1, 2, 5, 5, 9, 6, 0, 4, 6,
4, 4, 7, 7, 5, 3, 9, 0, 6, 2, 5, 2, 9, 8, 0, 2, 3, 2, 2, 3, 8, 7, 6, 9, 5, 3, 1, 2, 5, 1,
4, 9, 0, 1, 1, 6, 1, 1, 9, 3, 8, 4, 7, 6, 5, 6, 2, 5, 7, 4, 5, 0, 5, 8, 0, 5, 9, 6, 9, 2,
3, 8, 2, 8, 1, 2, 5, 3, 7, 2, 5, 2, 9, 0, 2, 9, 8, 4, 6, 1, 9, 1, 4, 0, 6, 2, 5, 1, 8, 6,
2, 6, 4, 5, 1, 4, 9, 2, 3, 0, 9, 5, 7, 0, 3, 1, 2, 5, 9, 3, 1, 3, 2, 2, 5, 7, 4, 6, 1, 5,
4, 7, 8, 5, 1, 5, 6, 2, 5, 4, 6, 5, 6, 6, 1, 2, 8, 7, 3, 0, 7, 7, 3, 9, 2, 5, 7, 8, 1, 2,
5, 2, 3, 2, 8, 3, 0, 6, 4, 3, 6, 5, 3, 8, 6, 9, 6, 2, 8, 9, 0, 6, 2, 5, 1, 1, 6, 4, 1, 5,
3, 2, 1, 8, 2, 6, 9, 3, 4, 8, 1, 4, 4, 5, 3, 1, 2, 5, 5, 8, 2, 0, 7, 6, 6, 0, 9, 1, 3, 4,
6, 7, 4, 0, 7, 2, 2, 6, 5, 6, 2, 5, 2, 9, 1, 0, 3, 8, 3, 0, 4, 5, 6, 7, 3, 3, 7, 0, 3, 6,
1, 3, 2, 8, 1, 2, 5, 1, 4, 5, 5, 1, 9, 1, 5, 2, 2, 8, 3, 6, 6, 8, 5, 1, 8, 0, 6, 6, 4, 0,
6, 2, 5, 7, 2, 7, 5, 9, 5, 7, 6, 1, 4, 1, 8, 3, 4, 2, 5, 9, 0, 3, 3, 2, 0, 3, 1, 2, 5, 3,
6, 3, 7, 9, 7, 8, 8, 0, 7, 0, 9, 1, 7, 1, 2, 9, 5, 1, 6, 6, 0, 1, 5, 6, 2, 5, 1, 8, 1, 8,
9, 8, 9, 4, 0, 3, 5, 4, 5, 8, 5, 6, 4, 7, 5, 8, 3, 0, 0, 7, 8, 1, 2, 5, 9, 0, 9, 4, 9, 4,
7, 0, 1, 7, 7, 2, 9, 2, 8, 2, 3, 7, 9, 1, 5, 0, 3, 9, 0, 6, 2, 5, 4, 5, 4, 7, 4, 7, 3, 5,
0, 8, 8, 6, 4, 6, 4, 1, 1, 8, 9, 5, 7, 5, 1, 9, 5, 3, 1, 2, 5, 2, 2, 7, 3, 7, 3, 6, 7, 5,
4, 4, 3, 2, 3, 2, 0, 5, 9, 4, 7, 8, 7, 5, 9, 7, 6, 5, 6, 2, 5, 1, 1, 3, 6, 8, 6, 8, 3, 7,
7, 2, 1, 6, 1, 6, 0, 2, 9, 7, 3, 9, 3, 7, 9, 8, 8, 2, 8, 1, 2, 5, 5, 6, 8, 4, 3, 4, 1, 8,
8, 6, 0, 8, 0, 8, 0, 1, 4, 8, 6, 9, 6, 8, 9, 9, 4, 1, 4, 0, 6, 2, 5, 2, 8, 4, 2, 1, 7, 0,
9, 4, 3, 0, 4, 0, 4, 0, 0, 7, 4, 3, 4, 8, 4, 4, 9, 7, 0, 7, 0, 3, 1, 2, 5, 1, 4, 2, 1, 0,
8, 5, 4, 7, 1, 5, 2, 0, 2, 0, 0, 3, 7, 1, 7, 4, 2, 2, 4, 8, 5, 3, 5, 1, 5, 6, 2, 5, 7, 1,
0, 5, 4, 2, 7, 3, 5, 7, 6, 0, 1, 0, 0, 1, 8, 5, 8, 7, 1, 1, 2, 4, 2, 6, 7, 5, 7, 8, 1, 2,
5, 3, 5, 5, 2, 7, 1, 3, 6, 7, 8, 8, 0, 0, 5, 0, 0, 9, 2, 9, 3, 5, 5, 6, 2, 1, 3, 3, 7, 8,
9, 0, 6, 2, 5, 1, 7, 7, 6, 3, 5, 6, 8, 3, 9, 4, 0, 0, 2, 5, 0, 4, 6, 4, 6, 7, 7, 8, 1, 0,
6, 6, 8, 9, 4, 5, 3, 1, 2, 5, 8, 8, 8, 1, 7, 8, 4, 1, 9, 7, 0, 0, 1, 2, 5, 2, 3, 2, 3, 3,
8, 9, 0, 5, 3, 3, 4, 4, 7, 2, 6, 5, 6, 2, 5, 4, 4, 4, 0, 8, 9, 2, 0, 9, 8, 5, 0, 0, 6, 2,
6, 1, 6, 1, 6, 9, 4, 5, 2, 6, 6, 7, 2, 3, 6, 3, 2, 8, 1, 2, 5, 2, 2, 2, 0, 4, 4, 6, 0, 4,
9, 2, 5, 0, 3, 1, 3, 0, 8, 0, 8, 4, 7, 2, 6, 3, 3, 3, 6, 1, 8, 1, 6, 4, 0, 6, 2, 5, 1, 1,
1, 0, 2, 2, 3, 0, 2, 4, 6, 2, 5, 1, 5, 6, 5, 4, 0, 4, 2, 3, 6, 3, 1, 6, 6, 8, 0, 9, 0, 8,
2, 0, 3, 1, 2, 5, 5, 5, 5, 1, 1, 1, 5, 1, 2, 3, 1, 2, 5, 7, 8, 2, 7, 0, 2, 1, 1, 8, 1, 5,
8, 3, 4, 0, 4, 5, 4, 1, 0, 1, 5, 6, 2, 5, 2, 7, 7, 5, 5, 5, 7, 5, 6, 1, 5, 6, 2, 8, 9, 1,
3, 5, 1, 0, 5, 9, 0, 7, 9, 1, 7, 0, 2, 2, 7, 0, 5, 0, 7, 8, 1, 2, 5, 1, 3, 8, 7, 7, 7, 8,
7, 8, 0, 7, 8, 1, 4, 4, 5, 6, 7, 5, 5, 2, 9, 5, 3, 9, 5, 8, 5, 1, 1, 3, 5, 2, 5, 3, 9, 0,
6, 2, 5, 6, 9, 3, 8, 8, 9, 3, 9, 0, 3, 9, 0, 7, 2, 2, 8, 3, 7, 7, 6, 4, 7, 6, 9, 7, 9, 2,
5, 5, 6, 7, 6, 2, 6, 9, 5, 3, 1, 2, 5, 3, 4, 6, 9, 4, 4, 6, 9, 5, 1, 9, 5, 3, 6, 1, 4, 1,
8, 8, 8, 2, 3, 8, 4, 8, 9, 6, 2, 7, 8, 3, 8, 1, 3, 4, 7, 6, 5, 6, 2, 5, 1, 7, 3, 4, 7, 2,
3, 4, 7, 5, 9, 7, 6, 8, 0, 7, 0, 9, 4, 4, 1, 1, 9, 2, 4, 4, 8, 1, 3, 9, 1, 9, 0, 6, 7, 3,
8, 2, 8, 1, 2, 5, 8, 6, 7, 3, 6, 1, 7, 3, 7, 9, 8, 8, 4, 0, 3, 5, 4, 7, 2, 0, 5, 9, 6, 2,
2, 4, 0, 6, 9, 5, 9, 5, 3, 3, 6, 9, 1, 4, 0, 6, 2, 5,
];
shift &= 63;
let x_a = TABLE[shift];
let x_b = TABLE[shift + 1];
let num_new_digits = (x_a >> 11) as _;
let pow5_a = (0x7FF & x_a) as usize;
let pow5_b = (0x7FF & x_b) as usize;
let pow5 = &TABLE_POW5[pow5_a..];
for (i, &p5) in pow5.iter().enumerate().take(pow5_b - pow5_a) {
if i >= d.num_digits {
return num_new_digits - 1;
} else if d.digits[i] == p5 {
continue;
} else if d.digits[i] < p5 {
return num_new_digits - 1;
} else {
return num_new_digits;
}
}
num_new_digits
}