Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 176 insertions, 0 deletions

diff --git a/third_party/rust/ryu/src/f2s.rs b/third_party/rust/ryu/src/f2s.rs
new file mode 100644
index 0000000000..eeb457ac83
--- /dev/null
+++ b/third_party/rust/ryu/src/f2s.rs
@@ -0,0 +1,176 @@
+// Translated from C to Rust. The original C code can be found at
+// https://github.com/ulfjack/ryu and carries the following license:
+//
+// Copyright 2018 Ulf Adams
+//
+// The contents of this file may be used under the terms of the Apache License,
+// Version 2.0.
+//
+//    (See accompanying file LICENSE-Apache or copy at
+//     http://www.apache.org/licenses/LICENSE-2.0)
+//
+// Alternatively, the contents of this file may be used under the terms of
+// the Boost Software License, Version 1.0.
+//    (See accompanying file LICENSE-Boost or copy at
+//     https://www.boost.org/LICENSE_1_0.txt)
+//
+// Unless required by applicable law or agreed to in writing, this software
+// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.
+
+use crate::common::*;
+use crate::f2s_intrinsics::*;
+
+pub const FLOAT_MANTISSA_BITS: u32 = 23;
+pub const FLOAT_EXPONENT_BITS: u32 = 8;
+const FLOAT_BIAS: i32 = 127;
+pub use crate::f2s_intrinsics::{FLOAT_POW5_BITCOUNT, FLOAT_POW5_INV_BITCOUNT};
+
+// A floating decimal representing m * 10^e.
+pub struct FloatingDecimal32 {
+    pub mantissa: u32,
+    // Decimal exponent's range is -45 to 38
+    // inclusive, and can fit in i16 if needed.
+    pub exponent: i32,
+}
+
+#[cfg_attr(feature = "no-panic", inline)]
+pub fn f2d(ieee_mantissa: u32, ieee_exponent: u32) -> FloatingDecimal32 {
+    let (e2, m2) = if ieee_exponent == 0 {
+        (
+            // We subtract 2 so that the bounds computation has 2 additional bits.
+            1 - FLOAT_BIAS - FLOAT_MANTISSA_BITS as i32 - 2,
+            ieee_mantissa,
+        )
+    } else {
+        (
+            ieee_exponent as i32 - FLOAT_BIAS - FLOAT_MANTISSA_BITS as i32 - 2,
+            (1u32 << FLOAT_MANTISSA_BITS) | ieee_mantissa,
+        )
+    };
+    let even = (m2 & 1) == 0;
+    let accept_bounds = even;
+
+    // Step 2: Determine the interval of valid decimal representations.
+    let mv = 4 * m2;
+    let mp = 4 * m2 + 2;
+    // Implicit bool -> int conversion. True is 1, false is 0.
+    let mm_shift = (ieee_mantissa != 0 || ieee_exponent <= 1) as u32;
+    let mm = 4 * m2 - 1 - mm_shift;
+
+    // Step 3: Convert to a decimal power base using 64-bit arithmetic.
+    let mut vr: u32;
+    let mut vp: u32;
+    let mut vm: u32;
+    let e10: i32;
+    let mut vm_is_trailing_zeros = false;
+    let mut vr_is_trailing_zeros = false;
+    let mut last_removed_digit = 0u8;
+    if e2 >= 0 {
+        let q = log10_pow2(e2);
+        e10 = q as i32;
+        let k = FLOAT_POW5_INV_BITCOUNT + pow5bits(q as i32) - 1;
+        let i = -e2 + q as i32 + k;
+        vr = mul_pow5_inv_div_pow2(mv, q, i);
+        vp = mul_pow5_inv_div_pow2(mp, q, i);
+        vm = mul_pow5_inv_div_pow2(mm, q, i);
+        if q != 0 && (vp - 1) / 10 <= vm / 10 {
+            // We need to know one removed digit even if we are not going to loop below. We could use
+            // q = X - 1 above, except that would require 33 bits for the result, and we've found that
+            // 32-bit arithmetic is faster even on 64-bit machines.
+            let l = FLOAT_POW5_INV_BITCOUNT + pow5bits(q as i32 - 1) - 1;
+            last_removed_digit =
+                (mul_pow5_inv_div_pow2(mv, q - 1, -e2 + q as i32 - 1 + l) % 10) as u8;
+        }
+        if q <= 9 {
+            // The largest power of 5 that fits in 24 bits is 5^10, but q <= 9 seems to be safe as well.
+            // Only one of mp, mv, and mm can be a multiple of 5, if any.
+            if mv % 5 == 0 {
+                vr_is_trailing_zeros = multiple_of_power_of_5_32(mv, q);
+            } else if accept_bounds {
+                vm_is_trailing_zeros = multiple_of_power_of_5_32(mm, q);
+            } else {
+                vp -= multiple_of_power_of_5_32(mp, q) as u32;
+            }
+        }
+    } else {
+        let q = log10_pow5(-e2);
+        e10 = q as i32 + e2;
+        let i = -e2 - q as i32;
+        let k = pow5bits(i) - FLOAT_POW5_BITCOUNT;
+        let mut j = q as i32 - k;
+        vr = mul_pow5_div_pow2(mv, i as u32, j);
+        vp = mul_pow5_div_pow2(mp, i as u32, j);
+        vm = mul_pow5_div_pow2(mm, i as u32, j);
+        if q != 0 && (vp - 1) / 10 <= vm / 10 {
+            j = q as i32 - 1 - (pow5bits(i + 1) - FLOAT_POW5_BITCOUNT);
+            last_removed_digit = (mul_pow5_div_pow2(mv, (i + 1) as u32, j) % 10) as u8;
+        }
+        if q <= 1 {
+            // {vr,vp,vm} is trailing zeros if {mv,mp,mm} has at least q trailing 0 bits.
+            // mv = 4 * m2, so it always has at least two trailing 0 bits.
+            vr_is_trailing_zeros = true;
+            if accept_bounds {
+                // mm = mv - 1 - mm_shift, so it has 1 trailing 0 bit iff mm_shift == 1.
+                vm_is_trailing_zeros = mm_shift == 1;
+            } else {
+                // mp = mv + 2, so it always has at least one trailing 0 bit.
+                vp -= 1;
+            }
+        } else if q < 31 {
+            // TODO(ulfjack): Use a tighter bound here.
+            vr_is_trailing_zeros = multiple_of_power_of_2_32(mv, q - 1);
+        }
+    }
+
+    // Step 4: Find the shortest decimal representation in the interval of valid representations.
+    let mut removed = 0i32;
+    let output = if vm_is_trailing_zeros || vr_is_trailing_zeros {
+        // General case, which happens rarely (~4.0%).
+        while vp / 10 > vm / 10 {
+            vm_is_trailing_zeros &= vm - (vm / 10) * 10 == 0;
+            vr_is_trailing_zeros &= last_removed_digit == 0;
+            last_removed_digit = (vr % 10) as u8;
+            vr /= 10;
+            vp /= 10;
+            vm /= 10;
+            removed += 1;
+        }
+        if vm_is_trailing_zeros {
+            while vm % 10 == 0 {
+                vr_is_trailing_zeros &= last_removed_digit == 0;
+                last_removed_digit = (vr % 10) as u8;
+                vr /= 10;
+                vp /= 10;
+                vm /= 10;
+                removed += 1;
+            }
+        }
+        if vr_is_trailing_zeros && last_removed_digit == 5 && vr % 2 == 0 {
+            // Round even if the exact number is .....50..0.
+            last_removed_digit = 4;
+        }
+        // We need to take vr + 1 if vr is outside bounds or we need to round up.
+        vr + ((vr == vm && (!accept_bounds || !vm_is_trailing_zeros)) || last_removed_digit >= 5)
+            as u32
+    } else {
+        // Specialized for the common case (~96.0%). Percentages below are relative to this.
+        // Loop iterations below (approximately):
+        // 0: 13.6%, 1: 70.7%, 2: 14.1%, 3: 1.39%, 4: 0.14%, 5+: 0.01%
+        while vp / 10 > vm / 10 {
+            last_removed_digit = (vr % 10) as u8;
+            vr /= 10;
+            vp /= 10;
+            vm /= 10;
+            removed += 1;
+        }
+        // We need to take vr + 1 if vr is outside bounds or we need to round up.
+        vr + (vr == vm || last_removed_digit >= 5) as u32
+    };
+    let exp = e10 + removed;
+
+    FloatingDecimal32 {
+        exponent: exp,
+        mantissa: output,
+    }
+}