More efficient reading of Byte and Short values

Author: plokhotnyuk

jsoniter-scala-core/js/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/core/JsonReader.scala

@@ -2034,10 +2034,10 @@ final class JsonReader private[jsoniter_scala](
     var b =
       if (isToken) nextToken(head)
       else nextByte(head)
-    var isNeg = false
+    var s = 0
     if (b == '-') {
       b = nextByte(head)
-      isNeg = true
+      s = -1
     }
     if (b < '0' || b > '9') numberError()
     var x = b - '0'
@@ -2058,9 +2058,10 @@ final class JsonReader private[jsoniter_scala](
         pos += 1
       }
       head = pos
+      x ^= s
+      x -= s
       if ((b | 0x20) == 'e' || b == '.') numberError(pos)
-      if (isNeg) x = -x
-      else if (x == 128) byteOverflowError(pos - 1)
+      if (x == 128) byteOverflowError(pos - 1)
     }
     x.toByte
   }
@@ -2069,10 +2070,10 @@ final class JsonReader private[jsoniter_scala](
     var b =
       if (isToken) nextToken(head)
       else nextByte(head)
-    var isNeg = false
+    var s = 0
     if (b == '-') {
       b = nextByte(head)
-      isNeg = true
+      s = -1
     }
     if (b < '0' || b > '9') numberError()
     var x = b - '0'
@@ -2093,9 +2094,10 @@ final class JsonReader private[jsoniter_scala](
         pos += 1
       }
       head = pos
+      x ^= s
+      x -= s
       if ((b | 0x20) == 'e' || b == '.') numberError(pos)
-      if (isNeg) x = -x
-      else if (x == 32768) shortOverflowError(pos - 1)
+      if (x == 32768) shortOverflowError(pos - 1)
     }
     x.toShort
   }

jsoniter-scala-core/jvm/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/core/JsonReader.scala

@@ -1996,10 +1996,10 @@ final class JsonReader private[jsoniter_scala](
     var b =
       if (isToken) nextToken(head)
       else nextByte(head)
-    var isNeg = false
+    var s = 0
     if (b == '-') {
       b = nextByte(head)
-      isNeg = true
+      s = -1
     }
     if (b < '0' || b > '9') numberError()
     var x = b - '0'
@@ -2020,9 +2020,10 @@ final class JsonReader private[jsoniter_scala](
         pos += 1
       }
       head = pos
+      x ^= s
+      x -= s
       if ((b | 0x20) == 'e' || b == '.') numberError(pos)
-      if (isNeg) x = -x
-      else if (x == 128) byteOverflowError(pos - 1)
+      if (x == 128) byteOverflowError(pos - 1)
     }
     x.toByte
   }
@@ -2031,10 +2032,10 @@ final class JsonReader private[jsoniter_scala](
     var b =
       if (isToken) nextToken(head)
       else nextByte(head)
-    var isNeg = false
+    var s = 0
     if (b == '-') {
       b = nextByte(head)
-      isNeg = true
+      s = -1
     }
     if (b < '0' || b > '9') numberError()
     var x = b - '0'
@@ -2055,9 +2056,10 @@ final class JsonReader private[jsoniter_scala](
         pos += 1
       }
       head = pos
+      x ^= s
+      x -= s
       if ((b | 0x20) == 'e' || b == '.') numberError(pos)
-      if (isNeg) x = -x
-      else if (x == 32768) shortOverflowError(pos - 1)
+      if (x == 32768) shortOverflowError(pos - 1)
     }
     x.toShort
   }

jsoniter-scala-core/native/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/core/JsonReader.scala

@@ -1996,10 +1996,10 @@ final class JsonReader private[jsoniter_scala](
     var b =
       if (isToken) nextToken(head)
       else nextByte(head)
-    var isNeg = false
+    var s = 0
     if (b == '-') {
       b = nextByte(head)
-      isNeg = true
+      s = -1
     }
     if (b < '0' || b > '9') numberError()
     var x = b - '0'
@@ -2020,9 +2020,10 @@ final class JsonReader private[jsoniter_scala](
         pos += 1
       }
       head = pos
+      x ^= s
+      x -= s
       if ((b | 0x20) == 'e' || b == '.') numberError(pos)
-      if (isNeg) x = -x
-      else if (x == 128) byteOverflowError(pos - 1)
+      if (x == 128) byteOverflowError(pos - 1)
     }
     x.toByte
   }
@@ -2031,10 +2032,10 @@ final class JsonReader private[jsoniter_scala](
     var b =
       if (isToken) nextToken(head)
       else nextByte(head)
-    var isNeg = false
+    var s = 0
     if (b == '-') {
       b = nextByte(head)
-      isNeg = true
+      s = -1
     }
     if (b < '0' || b > '9') numberError()
     var x = b - '0'
@@ -2055,9 +2056,10 @@ final class JsonReader private[jsoniter_scala](
         pos += 1
       }
       head = pos
+      x ^= s
+      x -= s
       if ((b | 0x20) == 'e' || b == '.') numberError(pos)
-      if (isNeg) x = -x
-      else if (x == 32768) shortOverflowError(pos - 1)
+      if (x == 32768) shortOverflowError(pos - 1)
     }
     x.toShort
   }