Shorten prefixes for float constants

Change `SIGNIFICAND_*` to `SIG_*` and `EXPONENT_*` to `EXP_*`. This makes things more consistent with `libm`, and terseness is convenient here since there isn't anything to confuse.
rust-lang · Jan 3, 2025 · 85604d9 · 85604d9
1 parent ff0ca1f
commit 85604d9
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Showing 10 changed files with 111 additions and 116 deletions.
diff --git a/src/float/add.rs b/src/float/add.rs
@@ -13,14 +13,14 @@ where
     let zero = F::Int::ZERO;
 
     let bits = F::BITS.cast();
-    let significand_bits = F::SIGNIFICAND_BITS;
-    let max_exponent = F::EXPONENT_MAX;
+    let significand_bits = F::SIG_BITS;
+    let max_exponent = F::EXP_MAX;
 
     let implicit_bit = F::IMPLICIT_BIT;
-    let significand_mask = F::SIGNIFICAND_MASK;
+    let significand_mask = F::SIG_MASK;
     let sign_bit = F::SIGN_MASK as F::Int;
     let abs_mask = sign_bit - one;
-    let exponent_mask = F::EXPONENT_MASK;
+    let exponent_mask = F::EXP_MASK;
     let inf_rep = exponent_mask;
     let quiet_bit = implicit_bit >> 1;
     let qnan_rep = exponent_mask | quiet_bit;

diff --git a/src/float/cmp.rs b/src/float/cmp.rs
@@ -38,7 +38,7 @@ fn cmp<F: Float>(a: F, b: F) -> Result {
 
     let sign_bit = F::SIGN_MASK as F::Int;
     let abs_mask = sign_bit - one;
-    let exponent_mask = F::EXPONENT_MASK;
+    let exponent_mask = F::EXP_MASK;
     let inf_rep = exponent_mask;
 
     let a_rep = a.to_bits();
@@ -87,7 +87,7 @@ fn unord<F: Float>(a: F, b: F) -> bool {
 
     let sign_bit = F::SIGN_MASK as F::Int;
     let abs_mask = sign_bit - one;
-    let exponent_mask = F::EXPONENT_MASK;
+    let exponent_mask = F::EXP_MASK;
     let inf_rep = exponent_mask;
 
     let a_rep = a.to_bits();

diff --git a/src/float/conv.rs b/src/float/conv.rs
@@ -32,7 +32,7 @@ mod int_to_float {
     /// Usually 1 is subtracted from this function's result, so that a mantissa with the implicit
     /// bit set can be added back later.
     fn exp<I: Int, F: Float<Int: CastFrom<u32>>>(n: u32) -> F::Int {
-        F::Int::cast_from(F::EXPONENT_BIAS - 1 + I::BITS - n)
+        F::Int::cast_from(F::EXP_BIAS - 1 + I::BITS - n)
     }
 
     /// Adjust a mantissa with dropped bits to perform correct rounding.
@@ -54,17 +54,17 @@ mod int_to_float {
     /// value to cancel it out.
     fn repr<F: Float>(e: F::Int, m: F::Int) -> F::Int {
         // + rather than | so the mantissa can overflow into the exponent
-        (e << F::SIGNIFICAND_BITS) + m
+        (e << F::SIG_BITS) + m
     }
 
     /// Shift distance from a left-aligned integer to a smaller float.
     fn shift_f_lt_i<I: Int, F: Float>() -> u32 {
-        (I::BITS - F::BITS) + F::EXPONENT_BITS
+        (I::BITS - F::BITS) + F::EXP_BITS
     }
 
     /// Shift distance from an integer with `n` leading zeros to a smaller float.
     fn shift_f_gt_i<I: Int, F: Float>(n: u32) -> u32 {
-        F::SIGNIFICAND_BITS - I::BITS + 1 + n
+        F::SIG_BITS - I::BITS + 1 + n
     }
 
     /// Perform a signed operation as unsigned, then add the sign back.
@@ -85,9 +85,9 @@ mod int_to_float {
         }
         let n = i.leading_zeros();
         // Mantissa with implicit bit set (significant bits)
-        let m_base = (i << n) >> f32::EXPONENT_BITS;
+        let m_base = (i << n) >> f32::EXP_BITS;
         // Bits that will be dropped (insignificant bits)
-        let adj = (i << n) << (f32::SIGNIFICAND_BITS + 1);
+        let adj = (i << n) << (f32::SIG_BITS + 1);
         let m = m_adj::<f32>(m_base, adj);
         let e = exp::<u32, f32>(n) - 1;
         repr::<f32>(e, m)
@@ -116,7 +116,7 @@ mod int_to_float {
         let m = (i as u64) << (shift_f_gt_i::<u32, f128>(n) - 64);
         let e = exp::<u32, f128>(n) as u64 - 1;
         // High 64 bits of f128 representation.
-        let h = (e << (f128::SIGNIFICAND_BITS - 64)) + m;
+        let h = (e << (f128::SIG_BITS - 64)) + m;
 
         // Shift back to the high bits, the rest of the mantissa will always be 0.
         (h as u128) << 64
@@ -128,8 +128,8 @@ mod int_to_float {
         // Mantissa with implicit bit set
         let m_base: u32 = (i_m >> shift_f_lt_i::<u64, f32>()) as u32;
         // The entire lower half of `i` will be truncated (masked portion), plus the
-        // next `EXPONENT_BITS` bits.
-        let adj = (i_m >> f32::EXPONENT_BITS | i_m & 0xFFFF) as u32;
+        // next `EXP_BITS` bits.
+        let adj = (i_m >> f32::EXP_BITS | i_m & 0xFFFF) as u32;
         let m = m_adj::<f32>(m_base, adj);
         let e = if i == 0 { 0 } else { exp::<u64, f32>(n) - 1 };
         repr::<f32>(e, m)
@@ -141,8 +141,8 @@ mod int_to_float {
         }
         let n = i.leading_zeros();
         // Mantissa with implicit bit set
-        let m_base = (i << n) >> f64::EXPONENT_BITS;
-        let adj = (i << n) << (f64::SIGNIFICAND_BITS + 1);
+        let m_base = (i << n) >> f64::EXP_BITS;
+        let adj = (i << n) << (f64::SIG_BITS + 1);
         let m = m_adj::<f64>(m_base, adj);
         let e = exp::<u64, f64>(n) - 1;
         repr::<f64>(e, m)
@@ -167,7 +167,7 @@ mod int_to_float {
 
         // Within the upper `F::BITS`, everything except for the signifcand
         // gets truncated
-        let d1: u32 = (i_m >> (u128::BITS - f32::BITS - f32::SIGNIFICAND_BITS - 1)).cast();
+        let d1: u32 = (i_m >> (u128::BITS - f32::BITS - f32::SIG_BITS - 1)).cast();
 
         // The entire rest of `i_m` gets truncated. Zero the upper `F::BITS` then just
         // check if it is nonzero.
@@ -186,8 +186,8 @@ mod int_to_float {
         // Mantissa with implicit bit set
         let m_base: u64 = (i_m >> shift_f_lt_i::<u128, f64>()) as u64;
         // The entire lower half of `i` will be truncated (masked portion), plus the
-        // next `EXPONENT_BITS` bits.
-        let adj = (i_m >> f64::EXPONENT_BITS | i_m & 0xFFFF_FFFF) as u64;
+        // next `EXP_BITS` bits.
+        let adj = (i_m >> f64::EXP_BITS | i_m & 0xFFFF_FFFF) as u64;
         let m = m_adj::<f64>(m_base, adj);
         let e = if i == 0 { 0 } else { exp::<u128, f64>(n) - 1 };
         repr::<f64>(e, m)
@@ -200,8 +200,8 @@ mod int_to_float {
         }
         let n = i.leading_zeros();
         // Mantissa with implicit bit set
-        let m_base = (i << n) >> f128::EXPONENT_BITS;
-        let adj = (i << n) << (f128::SIGNIFICAND_BITS + 1);
+        let m_base = (i << n) >> f128::EXP_BITS;
+        let adj = (i << n) << (f128::SIG_BITS + 1);
         let m = m_adj::<f128>(m_base, adj);
         let e = exp::<u128, f128>(n) - 1;
         repr::<f128>(e, m)
@@ -362,29 +362,29 @@ where
     F::Int: CastFrom<u32>,
     u32: CastFrom<F::Int>,
 {
-    let int_max_exp = F::EXPONENT_BIAS + I::MAX.ilog2() + 1;
-    let foobar = F::EXPONENT_BIAS + I::UnsignedInt::BITS - 1;
+    let int_max_exp = F::EXP_BIAS + I::MAX.ilog2() + 1;
+    let foobar = F::EXP_BIAS + I::UnsignedInt::BITS - 1;
 
     if fbits < F::ONE.to_bits() {
         // < 0 gets rounded to 0
         I::ZERO
-    } else if fbits < F::Int::cast_from(int_max_exp) << F::SIGNIFICAND_BITS {
+    } else if fbits < F::Int::cast_from(int_max_exp) << F::SIG_BITS {
         // >= 1, < integer max
         let m_base = if I::UnsignedInt::BITS >= F::Int::BITS {
-            I::UnsignedInt::cast_from(fbits) << (I::BITS - F::SIGNIFICAND_BITS - 1)
+            I::UnsignedInt::cast_from(fbits) << (I::BITS - F::SIG_BITS - 1)
         } else {
-            I::UnsignedInt::cast_from(fbits >> (F::SIGNIFICAND_BITS - I::BITS + 1))
+            I::UnsignedInt::cast_from(fbits >> (F::SIG_BITS - I::BITS + 1))
         };
 
         // Set the implicit 1-bit.
         let m: I::UnsignedInt = I::UnsignedInt::ONE << (I::BITS - 1) | m_base;
 
         // Shift based on the exponent and bias.
-        let s: u32 = (foobar) - u32::cast_from(fbits >> F::SIGNIFICAND_BITS);
+        let s: u32 = (foobar) - u32::cast_from(fbits >> F::SIG_BITS);
 
         let unsigned = m >> s;
         map_inbounds(I::from_unsigned(unsigned))
-    } else if fbits <= F::EXPONENT_MASK {
+    } else if fbits <= F::EXP_MASK {
         // >= max (incl. inf)
         out_of_bounds()
     } else {

diff --git a/src/float/div.rs b/src/float/div.rs
@@ -105,16 +105,16 @@ where
     let hw = F::BITS / 2;
     let lo_mask = F::Int::MAX >> hw;
 
-    let significand_bits = F::SIGNIFICAND_BITS;
+    let significand_bits = F::SIG_BITS;
     // Saturated exponent, representing infinity
-    let exponent_sat: F::Int = F::EXPONENT_MAX.cast();
+    let exponent_sat: F::Int = F::EXP_MAX.cast();
 
-    let exponent_bias = F::EXPONENT_BIAS;
+    let exponent_bias = F::EXP_BIAS;
     let implicit_bit = F::IMPLICIT_BIT;
-    let significand_mask = F::SIGNIFICAND_MASK;
+    let significand_mask = F::SIG_MASK;
     let sign_bit = F::SIGN_MASK;
     let abs_mask = sign_bit - one;
-    let exponent_mask = F::EXPONENT_MASK;
+    let exponent_mask = F::EXP_MASK;
     let inf_rep = exponent_mask;
     let quiet_bit = implicit_bit >> 1;
     let qnan_rep = exponent_mask | quiet_bit;

diff --git a/src/float/extend.rs b/src/float/extend.rs
@@ -15,19 +15,19 @@ where
     let src_zero = F::Int::ZERO;
     let src_one = F::Int::ONE;
     let src_bits = F::BITS;
-    let src_sign_bits = F::SIGNIFICAND_BITS;
-    let src_exp_bias = F::EXPONENT_BIAS;
+    let src_sign_bits = F::SIG_BITS;
+    let src_exp_bias = F::EXP_BIAS;
     let src_min_normal = F::IMPLICIT_BIT;
-    let src_infinity = F::EXPONENT_MASK;
+    let src_infinity = F::EXP_MASK;
     let src_sign_mask = F::SIGN_MASK as F::Int;
     let src_abs_mask = src_sign_mask - src_one;
-    let src_qnan = F::SIGNIFICAND_MASK;
+    let src_qnan = F::SIG_MASK;
     let src_nan_code = src_qnan - src_one;
 
     let dst_bits = R::BITS;
-    let dst_sign_bits = R::SIGNIFICAND_BITS;
-    let dst_inf_exp = R::EXPONENT_MAX;
-    let dst_exp_bias = R::EXPONENT_BIAS;
+    let dst_sign_bits = R::SIG_BITS;
+    let dst_inf_exp = R::EXP_MAX;
+    let dst_exp_bias = R::EXP_BIAS;
     let dst_min_normal = R::IMPLICIT_BIT;
 
     let sign_bits_delta = dst_sign_bits - src_sign_bits;

diff --git a/src/float/mod.rs b/src/float/mod.rs
@@ -42,32 +42,32 @@ pub(crate) trait Float:
     const ZERO: Self;
     const ONE: Self;
 
-    /// The bitwidth of the float type
+    /// The bitwidth of the float type.
     const BITS: u32;
 
-    /// The bitwidth of the significand
-    const SIGNIFICAND_BITS: u32;
+    /// The bitwidth of the significand.
+    const SIG_BITS: u32;
 
-    /// The bitwidth of the exponent
-    const EXPONENT_BITS: u32 = Self::BITS - Self::SIGNIFICAND_BITS - 1;
+    /// The bitwidth of the exponent.
+    const EXP_BITS: u32 = Self::BITS - Self::SIG_BITS - 1;
 
     /// The saturated value of the exponent (infinite representation), in the rightmost postiion.
-    const EXPONENT_MAX: u32 = (1 << Self::EXPONENT_BITS) - 1;
+    const EXP_MAX: u32 = (1 << Self::EXP_BITS) - 1;
 
-    /// The exponent bias value
-    const EXPONENT_BIAS: u32 = Self::EXPONENT_MAX >> 1;
+    /// The exponent bias value.
+    const EXP_BIAS: u32 = Self::EXP_MAX >> 1;
 
-    /// A mask for the sign bit
+    /// A mask for the sign bit.
     const SIGN_MASK: Self::Int;
 
-    /// A mask for the significand
-    const SIGNIFICAND_MASK: Self::Int;
+    /// A mask for the significand.
+    const SIG_MASK: Self::Int;
 
-    /// The implicit bit of the float format
+    /// The implicit bit of the float format.
     const IMPLICIT_BIT: Self::Int;
 
-    /// A mask for the exponent
-    const EXPONENT_MASK: Self::Int;
+    /// A mask for the exponent.
+    const EXP_MASK: Self::Int;
 
     /// Returns `self` transmuted to `Self::Int`
     fn to_bits(self) -> Self::Int;
@@ -122,12 +122,12 @@ macro_rules! float_impl {
             const ONE: Self = 1.0;
 
             const BITS: u32 = $bits;
-            const SIGNIFICAND_BITS: u32 = $significand_bits;
+            const SIG_BITS: u32 = $significand_bits;
 
             const SIGN_MASK: Self::Int = 1 << (Self::BITS - 1);
-            const SIGNIFICAND_MASK: Self::Int = (1 << Self::SIGNIFICAND_BITS) - 1;
-            const IMPLICIT_BIT: Self::Int = 1 << Self::SIGNIFICAND_BITS;
-            const EXPONENT_MASK: Self::Int = !(Self::SIGN_MASK | Self::SIGNIFICAND_MASK);
+            const SIG_MASK: Self::Int = (1 << Self::SIG_BITS) - 1;
+            const IMPLICIT_BIT: Self::Int = 1 << Self::SIG_BITS;
+            const EXP_MASK: Self::Int = !(Self::SIGN_MASK | Self::SIG_MASK);
 
             fn to_bits(self) -> Self::Int {
                 self.to_bits()
@@ -142,8 +142,7 @@ macro_rules! float_impl {
                     // necessary builtin (__unordtf2) to test whether `f128` is NaN.
                     // FIXME(f16_f128): Remove once the nightly toolchain has the __unordtf2 builtin
                     // x is NaN if all the bits of the exponent are set and the significand is non-0
-                    x.to_bits() & $ty::EXPONENT_MASK == $ty::EXPONENT_MASK
-                        && x.to_bits() & $ty::SIGNIFICAND_MASK != 0
+                    x.to_bits() & $ty::EXP_MASK == $ty::EXP_MASK && x.to_bits() & $ty::SIG_MASK != 0
                 }
                 #[cfg(not(feature = "mangled-names"))]
                 fn is_nan(x: $ty) -> bool {
@@ -159,10 +158,10 @@ macro_rules! float_impl {
                 self.is_sign_negative()
             }
             fn exp(self) -> Self::ExpInt {
-                ((self.to_bits() & Self::EXPONENT_MASK) >> Self::SIGNIFICAND_BITS) as Self::ExpInt
+                ((self.to_bits() & Self::EXP_MASK) >> Self::SIG_BITS) as Self::ExpInt
             }
             fn frac(self) -> Self::Int {
-                self.to_bits() & Self::SIGNIFICAND_MASK
+                self.to_bits() & Self::SIG_MASK
             }
             fn imp_frac(self) -> Self::Int {
                 self.frac() | Self::IMPLICIT_BIT
@@ -173,21 +172,19 @@ macro_rules! float_impl {
             fn from_parts(negative: bool, exponent: Self::Int, significand: Self::Int) -> Self {
                 Self::from_bits(
                     ((negative as Self::Int) << (Self::BITS - 1))
-                        | ((exponent << Self::SIGNIFICAND_BITS) & Self::EXPONENT_MASK)
-                        | (significand & Self::SIGNIFICAND_MASK),
+                        | ((exponent << Self::SIG_BITS) & Self::EXP_MASK)
+                        | (significand & Self::SIG_MASK),
                 )
             }
             fn normalize(significand: Self::Int) -> (i32, Self::Int) {
-                let shift = significand
-                    .leading_zeros()
-                    .wrapping_sub(Self::EXPONENT_BITS);
+                let shift = significand.leading_zeros().wrapping_sub(Self::EXP_BITS);
                 (
                     1i32.wrapping_sub(shift as i32),
                     significand << shift as Self::Int,
                 )
             }
             fn is_subnormal(self) -> bool {
-                (self.to_bits() & Self::EXPONENT_MASK) == Self::Int::ZERO
+                (self.to_bits() & Self::EXP_MASK) == Self::Int::ZERO
             }
         }
     };

diff --git a/src/float/mul.rs b/src/float/mul.rs
@@ -13,20 +13,20 @@ where
     let zero = F::Int::ZERO;
 
     let bits = F::BITS;
-    let significand_bits = F::SIGNIFICAND_BITS;
-    let max_exponent = F::EXPONENT_MAX;
+    let significand_bits = F::SIG_BITS;
+    let max_exponent = F::EXP_MAX;
 
-    let exponent_bias = F::EXPONENT_BIAS;
+    let exponent_bias = F::EXP_BIAS;
 
     let implicit_bit = F::IMPLICIT_BIT;
-    let significand_mask = F::SIGNIFICAND_MASK;
-    let sign_bit = F::SIGN_MASK as F::Int;
+    let significand_mask = F::SIG_MASK;
+    let sign_bit = F::SIGN_MASK;
     let abs_mask = sign_bit - one;
-    let exponent_mask = F::EXPONENT_MASK;
+    let exponent_mask = F::EXP_MASK;
     let inf_rep = exponent_mask;
     let quiet_bit = implicit_bit >> 1;
     let qnan_rep = exponent_mask | quiet_bit;
-    let exponent_bits = F::EXPONENT_BITS;
+    let exponent_bits = F::EXP_BITS;
 
     let a_rep = a.to_bits();
     let b_rep = b.to_bits();