guiyanakuang commented on a change in pull request #917:
URL: https://github.com/apache/orc/pull/917#discussion_r717771143
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File path: c++/include/orc/orc-config.hh.in
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@@ -75,4 +75,38 @@
}
#endif
+#if defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__NT__)
+ namespace orc {
+ /**
+ * Compute value * repetitions, return false if overflow, return true
otherwise
+ * and save the result at the address pointed to by result
+ * imitates the jdk Math.multiplyExact implementation
+ * but this method makes the assumption that repetitions > 1
+ */
+ static bool multiplyExact(int64_t value, int64_t repetitions, int64_t*
result) {
+ int64_t r = value * repetitions;
+ if (((value < 0 ? -value : value) | repetitions) >> 31 != 0 && r /
repetitions != value) {
+ return false;
+ }
+ *result = r;
+ return true;
+ }
Review comment:
Hi @dongjoon-hyun @wgtmac. Finally passed the test. But it needs a
strict review.
The window environment overflow check I've mimicked the JDK implementation.
If there is a better way, please let me know.
In fact it doesn't work well on clang (the compiler has some unknown
behaviour that I don't know about)
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