Make loadedDictEnd an Index, not the Dict Len

2018-05-23 17:53:03 -04:00
parent 7ef85e0618
commit 298d24fa57
3 changed files with 10 additions and 2 deletions
@@ -594,14 +594,20 @@ MEM_STATIC U32 ZSTD_window_correctOverflow(ZSTD_window_t* window, U32 cycleLog,
 * ZSTD_window_enforceMaxDist():
 * Updates lowLimit so that:
 *    (srcEnd - base) - lowLimit == maxDist + loadedDictEnd
+ *
 * This allows a simple check that index >= lowLimit to see if index is valid.
 * This must be called before a block compression call, with srcEnd as the block
 * source end.
+ *
 * If loadedDictEndPtr is not NULL, we set it to zero once we update lowLimit.
 * This is because dictionaries are allowed to be referenced as long as the last
 * byte of the dictionary is in the window, but once they are out of range,
 * they cannot be referenced. If loadedDictEndPtr is NULL, we use
 * loadedDictEnd == 0.
+ *
+ * In normal dict mode, the dict is between lowLimit and dictLimit. In
+ * dictMatchState mode, lowLimit and dictLimit are the same, and the dictionary
+ * is below them. forceWindow and dictMatchState are therefore incompatible.
 */
 MEM_STATIC void ZSTD_window_enforceMaxDist(ZSTD_window_t* window,
                                           void const* srcEnd, U32 maxDist,