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use std::{io, mem, ptr, slice};
use Dec64;
const DEC_DIGITS_LUT: &'static[u8] =
b"0001020304050607080910111213141516171819\
2021222324252627282930313233343536373839\
4041424344454647484950515253545556575859\
6061626364656667686970717273747576777879\
8081828384858687888990919293949596979899";
const ZEROES: &'static[u8] = b"00000000000000000000000000000000";
impl Dec64 {
pub fn write<W: io::Write>(self, wr: &mut W) -> io::Result<()> {
let coefficient = self.coefficient();
let exponent = self.exponent();
if coefficient == 0 {
return wr.write_all(b"0");
} else if exponent == -128 {
return wr.write_all(b"nan");
}
let mut n = if coefficient >= 0 {
coefficient
} else {
try!(wr.write_all(b"-"));
(!coefficient).wrapping_add(1)
};
let mut buf: [u8; 30] = unsafe { mem::uninitialized() };
let mut curr = buf.len() as isize;
let buf_ptr = buf.as_mut_ptr();
let lut_ptr = DEC_DIGITS_LUT.as_ptr();
unsafe {
while n >= 10000 {
let rem = (n % 10000) as isize;
n /= 10000;
let d1 = (rem / 100) << 1;
let d2 = (rem % 100) << 1;
curr -= 4;
ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
ptr::copy_nonoverlapping(lut_ptr.offset(d2), buf_ptr.offset(curr + 2), 2);
}
let mut n = n as isize;
if n >= 100 {
let d1 = (n % 100) << 1;
n /= 100;
curr -= 2;
ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
}
if n < 10 {
curr -= 1;
*buf_ptr.offset(curr) = (n as u8) + 48;
} else {
let d1 = n << 1;
curr -= 2;
ptr::copy_nonoverlapping(lut_ptr.offset(d1), buf_ptr.offset(curr), 2);
}
if exponent < 0 {
let mut e = (!exponent).wrapping_add(1) as usize;
if e > 30 {
ptr::copy(buf_ptr.offset(1), buf_ptr, curr as usize);
*buf_ptr.offset(curr) = b'.';
curr -= 1;
e -= buf.len() - (curr as usize) - 2;
try!(wr.write_all(
slice::from_raw_parts(buf_ptr.offset(curr), buf.len() - curr as usize)
));
try!(wr.write_all(b"e-"));
let e = e as isize;
return if e > 100 {
try!(wr.write_all(b"1"));
wr.write_all(
slice::from_raw_parts(lut_ptr.offset((e % 100) << 1), 2)
)
} else if e > 10 {
wr.write_all(
slice::from_raw_parts(lut_ptr.offset(e << 1), 2)
)
} else {
wr.write_all(&[(e as u8) + b'0'])
};
} else {
let written = (buf.len() - curr as usize) - 1;
if e > written {
let zeroprefill = e - written;
curr -= zeroprefill as isize;
ptr::copy_nonoverlapping(ZEROES.as_ptr(), buf_ptr.offset(curr), zeroprefill);
}
ptr::copy(buf_ptr.offset(1), buf_ptr, buf.len() - (e as usize));
*buf_ptr.offset((buf.len() as isize) + (exponent as isize) - 1) = b'.';
curr -= 1;
}
} else if exponent > 0 {
try!(wr.write_all(
slice::from_raw_parts(buf_ptr.offset(curr), buf.len() - curr as usize)
));
try!(wr.write_all(b"e"));
let e = exponent as isize;
return if e > 100 {
try!(wr.write_all(b"1"));
wr.write_all(
slice::from_raw_parts(lut_ptr.offset((e % 100) << 1), 2)
)
} else if e > 10 {
wr.write_all(
slice::from_raw_parts(lut_ptr.offset(e << 1), 2)
)
} else {
wr.write_all(&[(e as u8) + b'0'])
};
}
wr.write_all(
slice::from_raw_parts(buf_ptr.offset(curr), buf.len() - curr as usize)
)
}
}
}