Github user chenghao-intel commented on a diff in the pull request:
https://github.com/apache/spark/pull/6872#discussion_r33111483
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/math.scala
---
@@ -154,6 +156,216 @@ case class Cos(child: Expression) extends
UnaryMathExpression(math.cos, "COS")
case class Cosh(child: Expression) extends UnaryMathExpression(math.cosh,
"COSH")
+// This logic is borrowed from hive
+class ConvUtil {
+
+ private val value = new Array[Byte](64)
+
+ /**
+ * Divide x by m as if x is an unsigned 64-bit integer. Examples:
+ * unsignedLongDiv(-1, 2) == Long.MAX_VALUE unsignedLongDiv(6, 3) == 2
+ * unsignedLongDiv(0, 5) == 0
+ *
+ * @param x
+ * is treated as unsigned
+ * @param m
+ * is treated as signed
+ */
+ private def unsignedLongDiv(x: Long, m: Int): Long = {
+ if (x >= 0) {
+ x / m
+ } else {
+ // Let uval be the value of the unsigned long with the same bits as x
+ // Two's complement => x = uval - 2*MAX - 2
+ // => uval = x + 2*MAX + 2
+ // Now, use the fact: (a+b)/c = a/c + b/c + (a%c+b%c)/c
+ (x / m + 2 * (Long.MaxValue / m) + 2 / m + (x % m + 2 *
(Long.MaxValue % m) + 2 % m) / m)
+ }
+ }
+
+ /**
+ * Decode v into value[].
+ *
+ * @param v
+ * is treated as an unsigned 64-bit integer
+ * @param radix
+ * must be between MIN_RADIX and MAX_RADIX
+ */
+ private def decode(v: Long, radix: Int): Unit = {
+ var tmpV = v
+ Arrays.fill(value, 0.asInstanceOf[Byte])
+ var i = value.length - 1
+ while (tmpV != 0) {
+ val q = unsignedLongDiv(tmpV, radix)
+ value(i) = (tmpV - q * radix).asInstanceOf[Byte]
+ tmpV = q
+ i -= 1
+ }
+ }
+
+ /**
+ * Convert value[] into a long. On overflow, return -1 (as mySQL does).
If a
+ * negative digit is found, ignore the suffix starting there.
+ *
+ * @param radix
+ * must be between MIN_RADIX and MAX_RADIX
--- End diff --
should be in the same line
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