Re: [PATCH RFC 1/9] lib/lz4: import upstream LZ4 sources verbatim

[Michal Wilczynski]

On 9/30/26 08:07, Sergey Senozhatsky wrote:
> On (26/09/25 13:27), Michal Wilczynski wrote:
> [..]
> 
>> +void LZ4_resetStream_fast(LZ4_stream_t* ctx) {
>> +    LZ4_prepareTable(&(ctx->internal_donotuse), 0, byU32);
>> +}
> 
> [..]
> 
>> +void LZ4_attach_dictionary(LZ4_stream_t* workingStream, const LZ4_stream_t* dictionaryStream)
>> +{
>> +    const LZ4_stream_t_internal* dictCtx = (dictionaryStream == NULL) ? NULL :
>> +        &(dictionaryStream->internal_donotuse);
>> +
>> +    DEBUGLOG(4, "LZ4_attach_dictionary (%p, %p, size %u)",
>> +             workingStream, dictionaryStream,
>> +             dictCtx != NULL ? dictCtx->dictSize : 0);
>> +
>> +    if (dictCtx != NULL) {
>> +        /* If the current offset is zero, we will never look in the
>> +         * external dictionary context, since there is no value a table
>> +         * entry can take that indicate a miss. In that case, we need
>> +         * to bump the offset to something non-zero.
>> +         */
>> +        if (workingStream->internal_donotuse.currentOffset == 0) {
>> +            workingStream->internal_donotuse.currentOffset = 64 KB;
>> +        }
>> +
>> +        /* Don't actually attach an empty dictionary.
>> +         */
>> +        if (dictCtx->dictSize == 0) {
>> +            dictCtx = NULL;
>> +        }
>> +    }
>> +    workingStream->internal_donotuse.dictCtx = dictCtx;
>> +}
> 
> Just a side note,
> there is a bunch of new helpful API added in this release.  Currently,
> we do some memcpy hacks to avoid re-init of lz4 C/D-dict in zram, but
> once this series lands I'll be happy to send some trivial EXPORT_SYMBOL
> patches so that zram (and other lz4 users) can use standard lz4 dict
> API instead of hacks.
> 

Sounds great, thank you !

Best regards,
-- 
Michal Wilczynski <m.wilczynski@xxxxxxxxxxx>