[NBKCoreKit] Comparisons (#85).

Sources/NBKCoreKit/Private/NBKStrictSignedInteger+Comparisons.swift

@@ -0,0 +1,51 @@
+//=----------------------------------------------------------------------------=
+// This source file is part of the Numberick open source project.
+//
+// Copyright (c) 2023 Oscar Byström Ericsson
+// Licensed under Apache License, Version 2.0
+//
+// See http://www.apache.org/licenses/LICENSE-2.0 for license information.
+//=----------------------------------------------------------------------------=
+
+//*============================================================================*
+// MARK: * NBK x Strict Signed Integer x Comparisons
+//*============================================================================*
+//=----------------------------------------------------------------------------=
+// MARK: + where Base is Unsafe Buffer Pointer
+//=----------------------------------------------------------------------------=
+
+extension NBK.StrictSignedInteger {
+
+    //=------------------------------------------------------------------------=
+    // MARK: Utilities
+    //=------------------------------------------------------------------------=
+
+    /// A three-way comparison of `lhs` against `rhs`.
+    ///
+    /// ### Development
+    ///
+    /// Specializing this it where `T == UInt` makes it faster.
+    ///
+    @inlinable public static func compare<T>(_ lhs: Base, to rhs: Base) -> Int where Base == UnsafeBufferPointer<T> {
+        let lhs = NBK.SuccinctInt(fromStrictSignedInteger: lhs)!
+        let rhs = NBK.SuccinctInt(fromStrictSignedInteger: rhs)!
+        return lhs.compared(to: rhs) as Int
+    }
+
+    /// A three-way comparison of `lhs` against `rhs` at `index`.
+    ///
+    /// ### Development
+    ///
+    /// Specializing this it where `T == UInt` makes it faster.
+    ///
+    @inlinable public static func compare<T>(_ lhs: Base, to rhs: Base, at index: Int) -> Int where Base == UnsafeBufferPointer<T> {
+        let lhs = NBK.SuccinctInt(fromStrictSignedInteger: lhs)!
+        let rhs = NBK.SuccinctInt(fromStrictSignedInteger: rhs)!
+        let partition = Swift.min(index, lhs.body.endIndex)
+        let suffix = Base(rebasing:  lhs.body.suffix(from: partition))
+        let comparison = NBK.SuccinctInt(unchecked: suffix, sign: lhs.sign).compared(to: rhs)
+        if !comparison.isZero { return comparison }
+        let prefix = Base(rebasing:  lhs.body.prefix(upTo: partition))
+        return Int(bit: partition == index ? !prefix.allSatisfy({ $0.isZero }) : lhs.sign)
+    }
+}

Sources/NBKCoreKit/Private/NBKStrictUnsignedInteger+Comparisons.swift

@@ -38,9 +38,7 @@ extension NBK.StrictUnsignedInteger.SubSequence {
         let partition = Swift.min(index, lhs.endIndex)
         let suffix = Base(rebasing: lhs.suffix(from: partition))
         let comparison = self.compare(suffix, to: rhs) as Int
-        //=--------------------------------------=
         if !comparison.isZero { return comparison }
-        //=--------------------------------------=
         let prefix = Base(rebasing: lhs.prefix(upTo: partition))
         return Int(bit: !prefix.allSatisfy({ $0.isZero }))
     }

Tests/NBKCoreKitBenchmarks/Private/NBK+Limbs+Comparisons.swift → Tests/NBKCoreKitBenchmarks/Private/NBKStrictSignedInteger+Comparisons.swift

@@ -17,24 +17,26 @@ private typealias X = [UInt64]
 private typealias Y = [UInt32]
 
 //*============================================================================*
-// MARK: * NBK x Limbs x Comparisons
+// MARK: * NBK x Strict Signed Integer x Comparisons
 //*============================================================================*
 
-final class NBKBenchmarksOnLimbsByComparisons: XCTestCase {
+final class NBKStrictSignedIntegerBenchmarksOnComparisons: XCTestCase {
 
+    typealias T = NBK.StrictSignedInteger<UnsafeBufferPointer<UInt>>
+
     //=------------------------------------------------------------------------=
     // MARK: Tests
     //=------------------------------------------------------------------------=
 
-    func testCompareStrictSignedInteger() {
+    func testCompare() {
         var lhs = NBK.blackHoleIdentity([1, 2, 3, 4] as W)
         var rhs = NBK.blackHoleIdentity([1, 2, 3, 4] as W)
         var xyz = NBK.blackHoleIdentity((1) as Int)
 
         for _ in 0 ..< 2_500_000 {
             lhs.withUnsafeBufferPointer { lhs in
             rhs.withUnsafeBufferPointer { rhs in
-                NBK.blackHole(NBK.compareStrictSignedInteger(lhs, to: rhs))
+                NBK.blackHole(T.compare(lhs, to: rhs))
             }}
 
             NBK.blackHoleInoutIdentity(&lhs)
@@ -43,15 +45,15 @@ final class NBKBenchmarksOnLimbsByComparisons: XCTestCase {
         }
     }
 
-    func testCompareStrictSignedIntegerAtIndex() {
+    func testCompareAtIndex() {
         var lhs = NBK.blackHoleIdentity([1, 2, 3, 4] as W)
         var rhs = NBK.blackHoleIdentity([2, 3, 4, 0] as W)
         var xyz = NBK.blackHoleIdentity((1) as Int)
 
         for _ in 0 ..< 2_500_000 {
             lhs.withUnsafeBufferPointer { lhs in
             rhs.withUnsafeBufferPointer { rhs in
-                NBK.blackHole(NBK.compareStrictSignedInteger(lhs, to: rhs, at: xyz))
+                NBK.blackHole(T.compare(lhs, to: rhs, at: xyz))
             }}
 
             NBK.blackHoleInoutIdentity(&lhs)