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Diffstat (limited to 'vendor/ryu/src/s2d.rs')
| -rw-r--r-- | vendor/ryu/src/s2d.rs | 217 |
1 files changed, 0 insertions, 217 deletions
diff --git a/vendor/ryu/src/s2d.rs b/vendor/ryu/src/s2d.rs deleted file mode 100644 index 152ca97..0000000 --- a/vendor/ryu/src/s2d.rs +++ /dev/null @@ -1,217 +0,0 @@ -use crate::common::*; -use crate::d2s; -use crate::d2s_intrinsics::*; -use crate::parse::Error; -#[cfg(feature = "no-panic")] -use no_panic::no_panic; - -const DOUBLE_EXPONENT_BIAS: usize = 1023; - -fn floor_log2(value: u64) -> u32 { - 63_u32.wrapping_sub(value.leading_zeros()) -} - -#[cfg_attr(feature = "no-panic", no_panic)] -pub fn s2d(buffer: &[u8]) -> Result<f64, Error> { - let len = buffer.len(); - if len == 0 { - return Err(Error::InputTooShort); - } - - let mut m10digits = 0; - let mut e10digits = 0; - let mut dot_index = len; - let mut e_index = len; - let mut m10 = 0u64; - let mut e10 = 0i32; - let mut signed_m = false; - let mut signed_e = false; - - let mut i = 0; - if unsafe { *buffer.get_unchecked(0) } == b'-' { - signed_m = true; - i += 1; - } - - while let Some(c) = buffer.get(i).copied() { - if c == b'.' { - if dot_index != len { - return Err(Error::MalformedInput); - } - dot_index = i; - i += 1; - continue; - } - if c < b'0' || c > b'9' { - break; - } - if m10digits >= 17 { - return Err(Error::InputTooLong); - } - m10 = 10 * m10 + (c - b'0') as u64; - if m10 != 0 { - m10digits += 1; - } - i += 1; - } - - if let Some(b'e') | Some(b'E') = buffer.get(i) { - e_index = i; - i += 1; - match buffer.get(i) { - Some(b'-') => { - signed_e = true; - i += 1; - } - Some(b'+') => i += 1, - _ => {} - } - while let Some(c) = buffer.get(i).copied() { - if c < b'0' || c > b'9' { - return Err(Error::MalformedInput); - } - if e10digits > 3 { - // TODO: Be more lenient. Return +/-Infinity or +/-0 instead. - return Err(Error::InputTooLong); - } - e10 = 10 * e10 + (c - b'0') as i32; - if e10 != 0 { - e10digits += 1; - } - i += 1; - } - } - - if i < len { - return Err(Error::MalformedInput); - } - if signed_e { - e10 = -e10; - } - e10 -= if dot_index < e_index { - (e_index - dot_index - 1) as i32 - } else { - 0 - }; - if m10 == 0 { - return Ok(if signed_m { -0.0 } else { 0.0 }); - } - - if m10digits + e10 <= -324 || m10 == 0 { - // Number is less than 1e-324, which should be rounded down to 0; return - // +/-0.0. - let ieee = (signed_m as u64) << (d2s::DOUBLE_EXPONENT_BITS + d2s::DOUBLE_MANTISSA_BITS); - return Ok(f64::from_bits(ieee)); - } - if m10digits + e10 >= 310 { - // Number is larger than 1e+309, which should be rounded to +/-Infinity. - let ieee = ((signed_m as u64) << (d2s::DOUBLE_EXPONENT_BITS + d2s::DOUBLE_MANTISSA_BITS)) - | (0x7ff_u64 << d2s::DOUBLE_MANTISSA_BITS); - return Ok(f64::from_bits(ieee)); - } - - // Convert to binary float m2 * 2^e2, while retaining information about - // whether the conversion was exact (trailing_zeros). - let e2: i32; - let m2: u64; - let mut trailing_zeros: bool; - if e10 >= 0 { - // The length of m * 10^e in bits is: - // log2(m10 * 10^e10) = log2(m10) + e10 log2(10) = log2(m10) + e10 + e10 * log2(5) - // - // We want to compute the DOUBLE_MANTISSA_BITS + 1 top-most bits (+1 for - // the implicit leading one in IEEE format). We therefore choose a - // binary output exponent of - // log2(m10 * 10^e10) - (DOUBLE_MANTISSA_BITS + 1). - // - // We use floor(log2(5^e10)) so that we get at least this many bits; - // better to have an additional bit than to not have enough bits. - e2 = floor_log2(m10) - .wrapping_add(e10 as u32) - .wrapping_add(log2_pow5(e10) as u32) - .wrapping_sub(d2s::DOUBLE_MANTISSA_BITS + 1) as i32; - - // We now compute [m10 * 10^e10 / 2^e2] = [m10 * 5^e10 / 2^(e2-e10)]. - // To that end, we use the DOUBLE_POW5_SPLIT table. - let j = e2 - .wrapping_sub(e10) - .wrapping_sub(ceil_log2_pow5(e10)) - .wrapping_add(d2s::DOUBLE_POW5_BITCOUNT); - debug_assert!(j >= 0); - debug_assert!(e10 < d2s::DOUBLE_POW5_SPLIT.len() as i32); - m2 = mul_shift_64( - m10, - unsafe { d2s::DOUBLE_POW5_SPLIT.get_unchecked(e10 as usize) }, - j as u32, - ); - - // We also compute if the result is exact, i.e., - // [m10 * 10^e10 / 2^e2] == m10 * 10^e10 / 2^e2. - // This can only be the case if 2^e2 divides m10 * 10^e10, which in turn - // requires that the largest power of 2 that divides m10 + e10 is - // greater than e2. If e2 is less than e10, then the result must be - // exact. Otherwise we use the existing multiple_of_power_of_2 function. - trailing_zeros = - e2 < e10 || e2 - e10 < 64 && multiple_of_power_of_2(m10, (e2 - e10) as u32); - } else { - e2 = floor_log2(m10) - .wrapping_add(e10 as u32) - .wrapping_sub(ceil_log2_pow5(-e10) as u32) - .wrapping_sub(d2s::DOUBLE_MANTISSA_BITS + 1) as i32; - let j = e2 - .wrapping_sub(e10) - .wrapping_add(ceil_log2_pow5(-e10)) - .wrapping_sub(1) - .wrapping_add(d2s::DOUBLE_POW5_INV_BITCOUNT); - debug_assert!(-e10 < d2s::DOUBLE_POW5_INV_SPLIT.len() as i32); - m2 = mul_shift_64( - m10, - unsafe { d2s::DOUBLE_POW5_INV_SPLIT.get_unchecked(-e10 as usize) }, - j as u32, - ); - trailing_zeros = multiple_of_power_of_5(m10, -e10 as u32); - } - - // Compute the final IEEE exponent. - let mut ieee_e2 = i32::max(0, e2 + DOUBLE_EXPONENT_BIAS as i32 + floor_log2(m2) as i32) as u32; - - if ieee_e2 > 0x7fe { - // Final IEEE exponent is larger than the maximum representable; return +/-Infinity. - let ieee = ((signed_m as u64) << (d2s::DOUBLE_EXPONENT_BITS + d2s::DOUBLE_MANTISSA_BITS)) - | (0x7ff_u64 << d2s::DOUBLE_MANTISSA_BITS); - return Ok(f64::from_bits(ieee)); - } - - // We need to figure out how much we need to shift m2. The tricky part is - // that we need to take the final IEEE exponent into account, so we need to - // reverse the bias and also special-case the value 0. - let shift = if ieee_e2 == 0 { 1 } else { ieee_e2 as i32 } - .wrapping_sub(e2) - .wrapping_sub(DOUBLE_EXPONENT_BIAS as i32) - .wrapping_sub(d2s::DOUBLE_MANTISSA_BITS as i32); - debug_assert!(shift >= 0); - - // We need to round up if the exact value is more than 0.5 above the value - // we computed. That's equivalent to checking if the last removed bit was 1 - // and either the value was not just trailing zeros or the result would - // otherwise be odd. - // - // We need to update trailing_zeros given that we have the exact output - // exponent ieee_e2 now. - trailing_zeros &= (m2 & ((1_u64 << (shift - 1)) - 1)) == 0; - let last_removed_bit = (m2 >> (shift - 1)) & 1; - let round_up = last_removed_bit != 0 && (!trailing_zeros || ((m2 >> shift) & 1) != 0); - - let mut ieee_m2 = (m2 >> shift).wrapping_add(round_up as u64); - debug_assert!(ieee_m2 <= 1_u64 << (d2s::DOUBLE_MANTISSA_BITS + 1)); - ieee_m2 &= (1_u64 << d2s::DOUBLE_MANTISSA_BITS) - 1; - if ieee_m2 == 0 && round_up { - // Due to how the IEEE represents +/-Infinity, we don't need to check - // for overflow here. - ieee_e2 += 1; - } - let ieee = ((((signed_m as u64) << d2s::DOUBLE_EXPONENT_BITS) | ieee_e2 as u64) - << d2s::DOUBLE_MANTISSA_BITS) - | ieee_m2; - Ok(f64::from_bits(ieee)) -} |