ddidderr/zstd-rs
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Increase maximum window size

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* Maximum window size in 32-bit mode is 1GB, since allocations for 2GB fail
  on my Mac.
* Maximum window size in 64-bit mode is 2GB, since that is the largest
  power of 2 that works with the overflow prevention.
* Allow `--long=windowLog` to set the window log, along with
  `--zstd=wlog=#`. These options also set the window size during
  decompression, but don't override `--memory=#` if it is set.
* Present a helpful error message when the window size is too large during
  decompression.
* The long range matcher defaults to a hash log 7 less than the window log,
  which keeps it at 20 for window log 27.
* Keep the default long range matcher window size and the default maximum
  window size at 27 for the API and CLI.
* Add tests that use the maximum window size and hash size for compression
  and decompression.
This commit is contained in:
Nick Terrell
2017-09-26 14:00:01 -07:00
parent 8a4d0abc1c
commit c233bdbaee
12 changed files with 139 additions and 40 deletions
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lib/compress/zstd_ldm.c
+6 -2
View File
@@ -14,14 +14,14 @@
#define LDM_BUCKET_SIZE_LOG 3
#define LDM_MIN_MATCH_LENGTH 64
#define LDM_HASH_LOG 20
#define LDM_HASH_RLOG 7
#define LDM_HASH_CHAR_OFFSET 10
size_t ZSTD_ldm_initializeParameters(ldmParams_t* params, U32 enableLdm)
{
ZSTD_STATIC_ASSERT(LDM_BUCKET_SIZE_LOG <= ZSTD_LDM_BUCKETSIZELOG_MAX);
params->enableLdm = enableLdm>0;
params->hashLog = LDM_HASH_LOG;
params->hashLog = 0;
params->bucketSizeLog = LDM_BUCKET_SIZE_LOG;
params->minMatchLength = LDM_MIN_MATCH_LENGTH;
params->hashEveryLog = ZSTD_LDM_HASHEVERYLOG_NOTSET;
@@ -30,6 +30,10 @@ size_t ZSTD_ldm_initializeParameters(ldmParams_t* params, U32 enableLdm)
void ZSTD_ldm_adjustParameters(ldmParams_t* params, U32 windowLog)
{
if (params->hashLog == 0) {
params->hashLog = MAX(ZSTD_HASHLOG_MIN, windowLog - LDM_HASH_RLOG);
assert(params->hashLog <= ZSTD_HASHLOG_MAX);
}
if (params->hashEveryLog == ZSTD_LDM_HASHEVERYLOG_NOTSET) {
params->hashEveryLog =
windowLog < params->hashLog ? 0 : windowLog - params->hashLog;