From 5697b3dece084e4098337a22fa4ef763295c5117 Mon Sep 17 00:00:00 2001
From: sebres <serg.brester@sebres.de>
Date: Thu, 14 Sep 2023 16:48:14 +0200
Subject: [PATCH] zstd compression - set source size as hint if it is known e.
 g. by file compression (slightly better performance and/or compression
 ratio); although the feature still calling as "experimental", but zstd uses
 this in its own client since v.1.4 IIRC and the only known drawback would be
 significant regress of compression ration if guess considerably
 underestimates, but it does no matter in case of known file size.

---
 CPP/7zip/Archive/ZstdHandler.cpp  | 1 +
 CPP/7zip/Compress/ZstdEncoder.cpp | 8 +++++++-
 CPP/7zip/Compress/ZstdEncoder.h   | 3 +++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/CPP/7zip/Archive/ZstdHandler.cpp b/CPP/7zip/Archive/ZstdHandler.cpp
index e5b0148f..b93e3f3a 100644
--- a/CPP/7zip/Archive/ZstdHandler.cpp
+++ b/CPP/7zip/Archive/ZstdHandler.cpp
@@ -286,6 +286,7 @@ static HRESULT UpdateArchive(
   CMyComPtr<ICompressProgressInfo> localProgress = localProgressSpec;
   localProgressSpec->Init(updateCallback, true);
   NCompress::NZSTD::CEncoder *encoderSpec = new NCompress::NZSTD::CEncoder;
+  encoderSpec->unpackSize = unpackSize;
   CMyComPtr<ICompressCoder> encoder = encoderSpec;
   RINOK(props.SetCoderProps(encoderSpec, NULL));
   RINOK(encoder->Code(fileInStream, outStream, NULL, NULL, localProgress));
diff --git a/CPP/7zip/Compress/ZstdEncoder.cpp b/CPP/7zip/Compress/ZstdEncoder.cpp
index bf5c8fa4..b7c6543e 100644
--- a/CPP/7zip/Compress/ZstdEncoder.cpp
+++ b/CPP/7zip/Compress/ZstdEncoder.cpp
@@ -30,7 +30,8 @@ CEncoder::CEncoder():
   _LdmHashLog(-1),
   _LdmMinMatch(-1),
   _LdmBucketSizeLog(-1),
-  _LdmHashRateLog(-1)
+  _LdmHashRateLog(-1),
+  unpackSize(0)
 {
   _props.clear();
 }
@@ -251,6 +252,11 @@ STDMETHODIMP CEncoder::Code(ISequentialInStream *inStream,
     err = ZSTD_CCtx_setParameter(_ctx, ZSTD_c_contentSizeFlag, 1);
     if (ZSTD_isError(err)) return E_INVALIDARG;
 
+    if (unpackSize) {
+      err = ZSTD_CCtx_setParameter(_ctx, ZSTD_c_srcSizeHint, (int)(unpackSize <= INT_MAX ? unpackSize : INT_MAX));
+      if (ZSTD_isError(err)) return E_INVALIDARG;
+    }
+
     /* enable ldm for large windowlog values */
     if (_WindowLog > 27 && _Long == 0)
       _Long = 1;
diff --git a/CPP/7zip/Compress/ZstdEncoder.h b/CPP/7zip/Compress/ZstdEncoder.h
index 56fe0671..814bdad0 100644
--- a/CPP/7zip/Compress/ZstdEncoder.h
+++ b/CPP/7zip/Compress/ZstdEncoder.h
@@ -67,6 +67,9 @@ class CEncoder:
   Int32 _LdmHashRateLog;
 
 public:
+
+  UInt64 unpackSize;
+
   MY_QUERYINTERFACE_BEGIN2(ICompressCoder)
   MY_QUERYINTERFACE_ENTRY(ICompressSetCoderMt)
   MY_QUERYINTERFACE_ENTRY(ICompressSetCoderProperties)