blob: 6b8095cbb97b14b17e23c00e9d16ce64ff944ec0 [file] [log] [blame]
mod exponent;
mod mantissa;
use core::{mem, ptr};
use self::exponent::*;
use self::mantissa::*;
use d2s;
use d2s::*;
use f2s;
use f2s::*;
#[cfg(feature = "no-panic")]
use no_panic::no_panic;
/// Print f64 to the given buffer and return number of bytes written. Human
/// readable formatting.
///
/// At most 24 bytes will be written.
///
/// ## Special cases
///
/// This function **does not** check for NaN or infinity. If the input
/// number is not a finite float, the printed representation will be some
/// correctly formatted but unspecified numerical value.
///
/// Please check [`is_finite`] yourself before calling this function, or
/// check [`is_nan`] and [`is_infinite`] and handle those cases yourself.
///
/// [`is_finite`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_finite
/// [`is_nan`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_nan
/// [`is_infinite`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_infinite
///
/// ## Safety
///
/// The `result` pointer argument must point to sufficiently many writable bytes
/// to hold Ryū's representation of `f`.
///
/// ## Example
///
/// ```rust
/// let f = 1.234f64;
///
/// unsafe {
/// let mut buffer: [u8; 24] = std::mem::uninitialized();
/// let n = ryu::raw::pretty_d2s_buffered_n(f, &mut buffer[0]);
/// let s = std::str::from_utf8_unchecked(&buffer[..n]);
/// assert_eq!(s, "1.234");
/// }
/// ```
#[cfg_attr(must_use_return, must_use)]
#[cfg_attr(feature = "no-panic", no_panic)]
pub unsafe fn d2s_buffered_n(f: f64, result: *mut u8) -> usize {
let bits = mem::transmute::<f64, u64>(f);
let sign = ((bits >> (DOUBLE_MANTISSA_BITS + DOUBLE_EXPONENT_BITS)) & 1) != 0;
let ieee_mantissa = bits & ((1u64 << DOUBLE_MANTISSA_BITS) - 1);
let ieee_exponent =
(bits >> DOUBLE_MANTISSA_BITS) as u32 & ((1u32 << DOUBLE_EXPONENT_BITS) - 1);
let mut index = 0isize;
if sign {
*result = b'-';
index += 1;
}
if ieee_exponent == 0 && ieee_mantissa == 0 {
ptr::copy_nonoverlapping(b"0.0".as_ptr(), result.offset(index), 3);
return sign as usize + 3;
}
let v = d2d(ieee_mantissa, ieee_exponent);
let length = d2s::decimal_length(v.mantissa) as isize;
let k = v.exponent as isize;
let kk = length + k; // 10^(kk-1) <= v < 10^kk
debug_assert!(k >= -324);
if 0 <= k && kk <= 16 {
// 1234e7 -> 12340000000.0
write_mantissa_long(v.mantissa, result.offset(index + length));
for i in length..kk {
*result.offset(index + i) = b'0';
}
*result.offset(index + kk) = b'.';
*result.offset(index + kk + 1) = b'0';
index as usize + kk as usize + 2
} else if 0 < kk && kk <= 16 {
// 1234e-2 -> 12.34
write_mantissa_long(v.mantissa, result.offset(index + length + 1));
ptr::copy(result.offset(index + 1), result.offset(index), kk as usize);
*result.offset(index + kk) = b'.';
index as usize + length as usize + 1
} else if -5 < kk && kk <= 0 {
// 1234e-6 -> 0.001234
*result.offset(index) = b'0';
*result.offset(index + 1) = b'.';
let offset = 2 - kk;
for i in 2..offset {
*result.offset(index + i) = b'0';
}
write_mantissa_long(v.mantissa, result.offset(index + length + offset));
index as usize + length as usize + offset as usize
} else if length == 1 {
// 1e30
*result.offset(index) = b'0' + v.mantissa as u8;
*result.offset(index + 1) = b'e';
index as usize + 2 + write_exponent3(kk - 1, result.offset(index + 2))
} else {
// 1234e30 -> 1.234e33
write_mantissa_long(v.mantissa, result.offset(index + length + 1));
*result.offset(index) = *result.offset(index + 1);
*result.offset(index + 1) = b'.';
*result.offset(index + length + 1) = b'e';
index as usize
+ length as usize
+ 2
+ write_exponent3(kk - 1, result.offset(index + length + 2))
}
}
/// Print f32 to the given buffer and return number of bytes written. Human
/// readable formatting.
///
/// At most 16 bytes will be written.
///
/// ## Special cases
///
/// This function **does not** check for NaN or infinity. If the input
/// number is not a finite float, the printed representation will be some
/// correctly formatted but unspecified numerical value.
///
/// Please check [`is_finite`] yourself before calling this function, or
/// check [`is_nan`] and [`is_infinite`] and handle those cases yourself.
///
/// [`is_finite`]: https://doc.rust-lang.org/std/primitive.f32.html#method.is_finite
/// [`is_nan`]: https://doc.rust-lang.org/std/primitive.f32.html#method.is_nan
/// [`is_infinite`]: https://doc.rust-lang.org/std/primitive.f32.html#method.is_infinite
///
/// ## Safety
///
/// The `result` pointer argument must point to sufficiently many writable bytes
/// to hold Ryū's representation of `f`.
///
/// ## Example
///
/// ```rust
/// let f = 1.234f32;
///
/// unsafe {
/// let mut buffer: [u8; 16] = std::mem::uninitialized();
/// let n = ryu::raw::pretty_f2s_buffered_n(f, &mut buffer[0]);
/// let s = std::str::from_utf8_unchecked(&buffer[..n]);
/// assert_eq!(s, "1.234");
/// }
/// ```
#[cfg_attr(must_use_return, must_use)]
#[cfg_attr(feature = "no-panic", no_panic)]
pub unsafe fn f2s_buffered_n(f: f32, result: *mut u8) -> usize {
let bits = mem::transmute::<f32, u32>(f);
let sign = ((bits >> (FLOAT_MANTISSA_BITS + FLOAT_EXPONENT_BITS)) & 1) != 0;
let ieee_mantissa = bits & ((1u32 << FLOAT_MANTISSA_BITS) - 1);
let ieee_exponent =
((bits >> FLOAT_MANTISSA_BITS) & ((1u32 << FLOAT_EXPONENT_BITS) - 1)) as u32;
let mut index = 0isize;
if sign {
*result = b'-';
index += 1;
}
if ieee_exponent == 0 && ieee_mantissa == 0 {
ptr::copy_nonoverlapping(b"0.0".as_ptr(), result.offset(index), 3);
return sign as usize + 3;
}
let v = f2d(ieee_mantissa, ieee_exponent);
let length = f2s::decimal_length(v.mantissa) as isize;
let k = v.exponent as isize;
let kk = length + k; // 10^(kk-1) <= v < 10^kk
debug_assert!(k >= -45);
if 0 <= k && kk <= 13 {
// 1234e7 -> 12340000000.0
write_mantissa(v.mantissa, result.offset(index + length));
for i in length..kk {
*result.offset(index + i) = b'0';
}
*result.offset(index + kk) = b'.';
*result.offset(index + kk + 1) = b'0';
index as usize + kk as usize + 2
} else if 0 < kk && kk <= 13 {
// 1234e-2 -> 12.34
write_mantissa(v.mantissa, result.offset(index + length + 1));
ptr::copy(result.offset(index + 1), result.offset(index), kk as usize);
*result.offset(index + kk) = b'.';
index as usize + length as usize + 1
} else if -6 < kk && kk <= 0 {
// 1234e-6 -> 0.001234
*result.offset(index) = b'0';
*result.offset(index + 1) = b'.';
let offset = 2 - kk;
for i in 2..offset {
*result.offset(index + i) = b'0';
}
write_mantissa(v.mantissa, result.offset(index + length + offset));
index as usize + length as usize + offset as usize
} else if length == 1 {
// 1e30
*result.offset(index) = b'0' + v.mantissa as u8;
*result.offset(index + 1) = b'e';
index as usize + 2 + write_exponent2(kk - 1, result.offset(index + 2))
} else {
// 1234e30 -> 1.234e33
write_mantissa(v.mantissa, result.offset(index + length + 1));
*result.offset(index) = *result.offset(index + 1);
*result.offset(index + 1) = b'.';
*result.offset(index + length + 1) = b'e';
index as usize
+ length as usize
+ 2
+ write_exponent2(kk - 1, result.offset(index + length + 2))
}
}