Merge pull request #3674 from obscuren/gaz64

params: core, core/vm, miner: 64bit gas instructions

1 files changed, 25 insertions, 0 deletions

diff --git a/common/math/integer.go b/common/math/integer.go
new file mode 100644
index 000000000..8162b1985
--- /dev/null
+++ b/common/math/integer.go
@@ -0,0 +1,25 @@
+package math
+
+import gmath "math"
+
+/*
+ * NOTE: The following methods need to be optimised using either bit checking or asm
+ */
+
+// SafeSub returns subtraction result and whether overflow occurred.
+func SafeSub(x, y uint64) (uint64, bool) {
+	return x - y, x < y
+}
+
+// SafeAdd returns the result and whether overflow occurred.
+func SafeAdd(x, y uint64) (uint64, bool) {
+	return x + y, y > gmath.MaxUint64-x
+}
+
+// SafeMul returns multiplication result and whether overflow occurred.
+func SafeMul(x, y uint64) (uint64, bool) {
+	if x == 0 {
+		return 0, false
+	}
+	return x * y, x != 0 && y != 0 && y > gmath.MaxUint64/x
+}