Fix sign bit shift

Author: natecook1000

Tests/BinaryParsingTests/FloatingPointTests.swift

@@ -34,6 +34,14 @@ enum Interesting {
     .nan, .signalingNaN,
   ]
 
+  static let float80OneLE: [UInt8] = [
+    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xff, 0x3f
+  ]
+
+  static let float80OneBE: [UInt8] = [
+    0x3f, 0xff, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+  ]
+
   #if !(os(Windows) || os(Android) || ($Embedded && !os(Linux) && !(os(macOS) || os(iOS) || os(watchOS) || os(tvOS)))) && (arch(i386) || arch(x86_64))
   static let float80s: [Float80] = [
     0.0, 1.0, 1000,
@@ -182,7 +190,7 @@ struct FloatingPointTests {
           #expect(value2.isSignalingNaN)
         }
       } else {
-        #expect(value1 == value)
+        #expect(value1 == value, "\(1)")
         #expect(value2 == value)
       }
     }
@@ -194,13 +202,32 @@ struct FloatingPointTests {
   }
 
   #if !(os(Windows) || os(Android) || ($Embedded && !os(Linux) && !(os(macOS) || os(iOS) || os(watchOS) || os(tvOS)))) && (arch(i386) || arch(x86_64))
+  @Test
+  func staticFloat80() throws {
+    let leValue = try Interesting.float80OneLE.withParserSpan(Float80.init(parsingLittleEndian:))
+    let beValue = try Interesting.float80OneBE.withParserSpan(Float80.init(parsingBigEndian:))
+
+    print(leValue,
+          String(leValue.exponentBitPattern, radix: 16),
+          String(leValue.significandBitPattern, radix: 16))
+    print(beValue,
+          String(beValue.exponentBitPattern, radix: 16),
+          String(beValue.significandBitPattern, radix: 16))
+    
+    #expect(leValue == 1.0)
+    #expect(beValue == 1.0)
+  }
+
   @Test(arguments: Interesting.float80s)
   func testFloat80RoundTrip(_ value: Float80) throws {
     let bytesLE = Array(littleEndian: value)
     let bytesBE = Array(bigEndian: value)
 
+    let hexBE = bytesBE.map { String($0, radix: 16) }.joined(separator: "_")
+    
     do {
-      let value1 = try bytesLE.withParserSpan(Float80.init(parsingLittleEndian:))
+      let value1 = try bytesLE.withParserSpan(
+        Float80.init(parsingLittleEndian:))
       let value2 = try bytesLE.withParserSpan { input in
         try Float80(parsing: &input, endianness: .little)
       }
@@ -225,14 +252,14 @@ struct FloatingPointTests {
       }
 
       if value.isNaN {
-        #expect(value1.isNaN)
+        #expect(value1.isNaN, "big: \(hexBE)")
         #expect(value2.isNaN)
         if value.isSignalingNaN {
           #expect(value1.isSignalingNaN)
           #expect(value2.isSignalingNaN)
         }
       } else {
-        #expect(value1 == value)
+        #expect(value1 == value, "big: \(hexBE)")
         #expect(value2 == value)
       }
     }

Tests/BinaryParsingTests/TestingSupport.swift

@@ -146,7 +146,7 @@ extension Array where Element == UInt8 {
       self.append(contentsOf: bytes)
     }
     let signAndExponent =
-      value.exponentBitPattern | (value.sign == .minus ? 1 : 0 << 31)
+      value.exponentBitPattern | ((value.sign == .minus ? 1 : 0) << 15)
     Swift.withUnsafeBytes(of: signAndExponent.littleEndian) { bytes in
       self.append(contentsOf: bytes)
     }
@@ -155,7 +155,7 @@ extension Array where Element == UInt8 {
   init(bigEndian value: Float80) {
     self = []
     let signAndExponent =
-      value.exponentBitPattern | (value.sign == .minus ? 1 : 0 << 31)
+      value.exponentBitPattern | ((value.sign == .minus ? 1 : 0) << 15)
     Swift.withUnsafeBytes(of: signAndExponent.bigEndian) { bytes in
       self.append(contentsOf: bytes)
     }