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https://issues.apache.org/jira/browse/ORC-445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16709049#comment-16709049
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ASF GitHub Bot commented on ORC-445:
------------------------------------
fangzheng commented on a change in pull request #346: ORC-445: [C++] Code
improvements in RLEV2Util.
URL: https://github.com/apache/orc/pull/346#discussion_r238772598
##########
File path: c++/src/RLEV2Util.hh
##########
@@ -23,85 +23,24 @@
namespace orc {
extern const uint32_t FBSToBitWidthMap[FixedBitSizes::SIZE];
+ extern const uint32_t ClosestFixedBitsMap[65];
+ extern const uint32_t ClosestAlignedFixedBitsMap[65];
+ extern const uint32_t BitWidthToFBSMap[65];
inline uint32_t decodeBitWidth(uint32_t n) {
return FBSToBitWidthMap[n];
}
inline uint32_t getClosestFixedBits(uint32_t n) {
- if (n == 0) {
- return 1;
- }
-
- if (n >= 1 && n <= 24) {
- return n;
- } else if (n <= 26) {
- return 26;
- } else if (n <= 28) {
- return 28;
- } else if (n <= 30) {
- return 30;
- } else if (n <= 32) {
- return 32;
- } else if (n <= 40) {
- return 40;
- } else if (n <= 48) {
- return 48;
- } else if (n <= 56) {
- return 56;
- } else {
- return 64;
- }
+ return ClosestFixedBitsMap[n];
Review comment:
@xndai Hi Xiening, thanks for the catch. When computing patch width, it is
possible for the input n to be larger than 64. I have added boundary check in
this function and getClosestAlignedFixedBits().
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> [C++] Code improvements in RLEV2Util
> ------------------------------------
>
> Key: ORC-445
> URL: https://issues.apache.org/jira/browse/ORC-445
> Project: ORC
> Issue Type: Improvement
> Components: C++
> Reporter: Fang Zheng
> Priority: Minor
>
> This is a follow-up of ORC-444. The following functions in RLEV2Util.hh can
> be optimized by replacing the if-else statements with direct array lookup:
> inline uint32_t getClosestFixedBits(uint32_t n);
> inline uint32_t getClosestAlignedFixedBits(uint32_t n);
> inline uint32_t encodeBitWidth(uint32_t n);
> inline uint32_t findClosestNumBits(int64_t value);
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