extended exact window size to greedy/lazy modes

diff --git a/lib/compress/zstd_lazy.c b/lib/compress/zstd_lazy.c
index aa932b511dedf19adaa92058e9ea2b4e02309dc8..94d906c01f1c801db7776f1f25857dcdfd0056b6 100644 (file)
--- a/lib/compress/zstd_lazy.c
+++ b/lib/compress/zstd_lazy.c
@@ -83,7 +83,10 @@ ZSTD_insertDUBT1(ZSTD_matchState_t* ms,
     U32* largerPtr  = smallerPtr + 1;
     U32 matchIndex = *smallerPtr;   /* this candidate is unsorted : next sorted candidate is reached through *smallerPtr, while *largerPtr contains previous unsorted candidate (which is already saved and can be overwritten) */
     U32 dummy32;   /* to be nullified at the end */
-    U32 const windowLow = ms->window.lowLimit;
+    U32 const windowValid = ms->window.lowLimit;
+    U32 const maxDistance = 1U << cParams->windowLog;
+    U32 const windowLow = (current - windowValid > maxDistance) ? current - maxDistance : windowValid;
+
 
     DEBUGLOG(8, "ZSTD_insertDUBT1(%u) (dictLimit=%u, lowLimit=%u)",
                 current, dictLimit, windowLow);
@@ -239,7 +242,9 @@ ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
 
     const BYTE* const base = ms->window.base;
     U32    const current = (U32)(ip-base);
-    U32    const windowLow = ms->window.lowLimit;
+    U32    const maxDistance = 1U << cParams->windowLog;
+    U32    const windowValid = ms->window.lowLimit;
+    U32    const windowLow = (current - windowValid > maxDistance) ? current - maxDistance : windowValid;
 
     U32*   const bt = ms->chainTable;
     U32    const btLog  = cParams->chainLog - 1;
@@ -490,8 +495,10 @@ size_t ZSTD_HcFindBestMatch_generic (
     const U32 dictLimit = ms->window.dictLimit;
     const BYTE* const prefixStart = base + dictLimit;
     const BYTE* const dictEnd = dictBase + dictLimit;
-    const U32 lowLimit = ms->window.lowLimit;
     const U32 current = (U32)(ip-base);
+    const U32 maxDistance = 1U << cParams->windowLog;
+    const U32 lowValid = ms->window.lowLimit;
+    const U32 lowLimit = (current - lowValid > maxDistance) ? current - maxDistance : lowValid;
     const U32 minChain = current > chainSize ? current - chainSize : 0;
     U32 nbAttempts = 1U << cParams->searchLog;
     size_t ml=4-1;