From b4f508608f8f9423350cf48e46dd22c452f0b809 Mon Sep 17 00:00:00 2001
From: jonrumsey <jrumsey@uk.ibm.com>
Date: Mon, 11 Jul 2022 11:28:32 +0100
Subject: Change definitions of LZ4_STREAMSIZE, LZ4_STREAMDECODESIZE and
 LZ4_STREAMHCSIZE to factor in OS400 pointer length and structure alignment
 rules

Update the length values on platforms where pointers are 16-bytes, factor in implicit compiler padding to ensure proper alignment of members and overall structure lengths
---
 lib/lz4.h   | 30 ++++++++++++++++++++++++++++--
 lib/lz4hc.h | 20 +++++++++++++++++++-
 2 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/lib/lz4.h b/lib/lz4.h
index 07cc18e..1bd7d26 100644
--- a/lib/lz4.h
+++ b/lib/lz4.h
@@ -631,8 +631,22 @@ typedef struct {
  *  Init this structure with LZ4_initStream() before first use.
  *  note : only use this definition in association with static linking !
  *  this definition is not API/ABI safe, and may change in future versions.
+ *  Note : OS400 pointers are 16 bytes and the compiler adds 8 bytes of padding after
+ *  tableType and 12 bytes after dictSize to ensure the structure is word aligned:
+ *  |=========================================================
+ *  |      Offset       |      Length       | Member Name
+ *  |=========================================================
+ *  |       0           |   16384           |  hashTable[4096]
+ *  |   16384           |       4           |  currentOffset
+ *  |   16388           |       4           |  tableType
+ *  |   16392           |       8           |  ***PADDING***
+ *  |   16400           |      16           |  dictionary
+ *  |   16416           |      16           |  dictCtx
+ *  |   16432           |       4           |  dictSize
+ *  |   16436           |      12           |  ***PADDING***
+ *  ==========================================================
  */
-#define LZ4_STREAMSIZE       ((1UL << LZ4_MEMORY_USAGE) + 32)  /* static size, for inter-version compatibility */
+#define LZ4_STREAMSIZE       ((1UL << LZ4_MEMORY_USAGE) + ((sizeof(void*)==16) ? 64 : 32))  /* static size, for inter-version compatibility */
 #define LZ4_STREAMSIZE_VOIDP (LZ4_STREAMSIZE / sizeof(void*))
 union LZ4_stream_u {
     void* table[LZ4_STREAMSIZE_VOIDP];
@@ -663,8 +677,20 @@ LZ4LIB_API LZ4_stream_t* LZ4_initStream (void* buffer, size_t size);
  *  note : only use in association with static linking !
  *         this definition is not API/ABI safe,
  *         and may change in a future version !
+ *  Note : Same story as LZ4_STREAMSIZE for OS400 in terms of additional padding to 
+ *         ensure pointers start on and structures finish on 16 byte boundaries
+ *         |=========================================================
+ *         |      Offset       |      Length       | Member Name
+ *         |=========================================================
+ *         |       0           |      16           |    externalDict 
+ *         |      16           |       4           |    extDictSize  
+ *         |      20           |      12           |    ***PADDING***
+ *         |      32           |      16           |    prefixEnd    
+ *         |      48           |       4           |    prefixSize   
+ *         |      52           |      12           |    ***PADDING***
+ *         ==========================================================
  */
-#define LZ4_STREAMDECODESIZE_U64 (4 + ((sizeof(void*)==16) ? 2 : 0) /*AS-400*/ )
+#define LZ4_STREAMDECODESIZE_U64 (4 + ((sizeof(void*)==16) ? 4 : 0))
 #define LZ4_STREAMDECODESIZE     (LZ4_STREAMDECODESIZE_U64 * sizeof(unsigned long long))
 union LZ4_streamDecode_u {
     unsigned long long table[LZ4_STREAMDECODESIZE_U64];
diff --git a/lib/lz4hc.h b/lib/lz4hc.h
index f4afc9b..6176457 100644
--- a/lib/lz4hc.h
+++ b/lib/lz4hc.h
@@ -219,8 +219,26 @@ struct LZ4HC_CCtx_internal
 
 /* Do not use these definitions directly !
  * Declare or allocate an LZ4_streamHC_t instead.
+ * Note : OS400 uses 16 byte pointers and so the structure size is larger than other
+ *        platforms
+ *        |===========================================================
+ *        |      Offset       |      Length       | Member Name       
+ *        |===========================================================
+ *        |       0           |  131072           |  hashTable[32768] 
+ *        |  131072           |  131072           |  chainTable[65536]
+ *        |  262144           |      16           |  end              
+ *        |  262160           |      16           |  base             
+ *        |  262176           |      16           |  dictBase         
+ *        |  262192           |       4           |  dictLimit        
+ *        |  262196           |       4           |  lowLimit         
+ *        |  262200           |       4           |  nextToUpdate     
+ *        |  262204           |       2           |  compressionLevel 
+ *        |  262206           |       1           |  favorDecSpeed    
+ *        |  262207           |       1           |  dirty            
+ *        |  262208           |      16           |  dictCtx           
+ *        ============================================================
  */
-#define LZ4_STREAMHCSIZE       262200  /* static size, for inter-version compatibility */
+#define LZ4_STREAMHCSIZE       (262200 + ((sizeof(void*)==16) ? 24 : 0)) /* static size, for inter-version compatibility */
 #define LZ4_STREAMHCSIZE_VOIDP (LZ4_STREAMHCSIZE / sizeof(void*))
 union LZ4_streamHC_u {
     void* table[LZ4_STREAMHCSIZE_VOIDP];
-- 
cgit v0.12