Implement 128 bits Unsigned Integer Multiplication and Division.

1 files changed, 18 insertions, 0 deletions

diff --git a/src/common/uint128.cpp b/src/common/uint128.cpp
new file mode 100644
index 000000000..aea7f03e2
--- /dev/null
+++ b/src/common/uint128.cpp
@@ -0,0 +1,18 @@
+
+namespace Common {
+
+std::pair<u64, u64> udiv128(u128 dividend, u64 divisor) {
+    u64 remainder = dividend[0] % divisor;
+    u64 accum = dividend[0] / divisor;
+    if (dividend[1] == 0)
+        return {accum, remainder};
+    // We ignore dividend[1] / divisor as that overflows
+    u64 first_segment = (dividend[1] % divisor) << 32;
+    accum += (first_segment / divisor) << 32;
+    u64 second_segment = (first_segment % divisor) << 32;
+    accum += (second_segment / divisor);
+    remainder += second_segment % divisor;
+    return {accum, remainder};
+}
+
+} // namespace Common