From: Yann Collet <yann.collet.73@gmail.com>
Date: Wed, 6 Jul 2016 00:25:44 +0000 (+0200)
Subject: simplified ZSTD_decodeSequence()
X-Git-Tag: v0.7.3^2~22
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fe07eaa972f44f71443806c13d0286fad15153e2;p=thirdparty%2Fzstd.git

simplified ZSTD_decodeSequence()
---

diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index 5a0d97657..9786ee171 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -688,16 +688,16 @@ static seq_t ZSTD_decodeSequence(seqState_t* seqState)
                             0x2000, 0x4000, 0x8000, 0x10000 };
 
     static const U32 ML_base[MaxML+1] = {
-                             0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10,   11,    12,    13,    14,    15,
-                            16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,   27,    28,    29,    30,    31,
-                            32, 34, 36, 38, 40, 44, 48, 56, 64, 80, 96, 0x80, 0x100, 0x200, 0x400, 0x800,
-                            0x1000, 0x2000, 0x4000, 0x8000, 0x10000 };
+                             3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13,   14,    15,    16,    17,    18,
+                            19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,   30,    31,    32,    33,    34,
+                            35, 37, 39, 41, 43, 47, 51, 59, 67, 83, 99, 0x83, 0x103, 0x203, 0x403, 0x803,
+                            0x1003, 0x2003, 0x4003, 0x8003, 0x10003 };
 
     static const U32 OF_base[MaxOff+1] = {
-                 0,        1,       3,       7,     0xF,     0x1F,     0x3F,     0x7F,
-                 0xFF,   0x1FF,   0x3FF,   0x7FF,   0xFFF,   0x1FFF,   0x3FFF,   0x7FFF,
-                 0xFFFF, 0x1FFFF, 0x3FFFF, 0x7FFFF, 0xFFFFF, 0x1FFFFF, 0x3FFFFF, 0x7FFFFF,
-                 0xFFFFFF, 0x1FFFFFF, 0x3FFFFFF, /*fake*/ 1, 1 };
+                 0,        1,       1,       5,     0xD,     0x1D,     0x3D,     0x7D,
+                 0xFD,   0x1FD,   0x3FD,   0x7FD,   0xFFD,   0x1FFD,   0x3FFD,   0x7FFD,
+                 0xFFFD, 0x1FFFD, 0x3FFFD, 0x7FFFD, 0xFFFFD, 0x1FFFFD, 0x3FFFFD, 0x7FFFFD,
+                 0xFFFFFD, 0x1FFFFFD, 0x3FFFFFD, /*fake*/ 1, 1 };
 
     /* sequence */
     {   size_t offset;
@@ -708,22 +708,18 @@ static seq_t ZSTD_decodeSequence(seqState_t* seqState)
             if (MEM_32bits()) BIT_reloadDStream(&(seqState->DStream));
         }
 
-        if (offset < ZSTD_REP_NUM) {
-            if (llCode == 0 && offset <= 1) offset = 1-offset;
+        if (ofCode <= 1) {
+            if ((llCode == 0) & (offset <= 1)) offset = 1-offset;
 
-            if (offset != 0) {
+            if (offset) {
                 size_t const temp = seqState->prevOffset[offset];
-                if (offset != 1) {
-                    seqState->prevOffset[2] = seqState->prevOffset[1];
-                }
+                if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
                 seqState->prevOffset[1] = seqState->prevOffset[0];
                 seqState->prevOffset[0] = offset = temp;
-
             } else {
                 offset = seqState->prevOffset[0];
             }
         } else {
-            offset -= ZSTD_REP_MOVE;
             seqState->prevOffset[2] = seqState->prevOffset[1];
             seqState->prevOffset[1] = seqState->prevOffset[0];
             seqState->prevOffset[0] = offset;
@@ -731,7 +727,7 @@ static seq_t ZSTD_decodeSequence(seqState_t* seqState)
         seq.offset = offset;
     }
 
-    seq.matchLength = ML_base[mlCode] + MINMATCH + ((mlCode>31) ? BIT_readBits(&(seqState->DStream), mlBits) : 0);   /* <=  16 bits */
+    seq.matchLength = ML_base[mlCode] + ((mlCode>31) ? BIT_readBits(&(seqState->DStream), mlBits) : 0);   /* <=  16 bits */
     if (MEM_32bits() && (mlBits+llBits>24)) BIT_reloadDStream(&(seqState->DStream));
 
     seq.litLength = LL_base[llCode] + ((llCode>15) ? BIT_readBits(&(seqState->DStream), llBits) : 0);   /* <=  16 bits */