Improved decoding speed, thanks to several contributions from Ludvig Strigeus (issues 49, 50 & 54)

Removed unnecessary assignment within LZ4_uncompress_unknownSize() (reported by Shivram)

git-svn-id: https://lz4.googlecode.com/svn/trunk@85 650e7d94-2a16-8b24-b05c-7c0b3f6821cd

1 files changed, 33 insertions, 30 deletions

diff --git a/lz4.c b/lz4.c
index a651748..00d6f95 100644
--- a/lz4.c
+++ b/lz4.c
@@ -701,10 +701,13 @@ int LZ4_uncompress(const char* source,
     BYTE* const oend = op + osize;

     BYTE* cpy;

 

-    BYTE token;

+    unsigned token;

 

-    int	len, length;

-    size_t dec[] ={0, 3, 2, 3, 0, 0, 0, 0};

+    size_t length;

+    size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};

+#if LZ4_ARCH64

+    size_t dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};

+#endif

 

 

     // Main Loop

@@ -712,7 +715,7 @@ int LZ4_uncompress(const char* source,
     {

         // get runlength

         token = *ip++;

-        if ((length=(token>>ML_BITS)) == RUN_MASK)  { for (;(len=*ip++)==255;length+=255){} length += len; }

+        if ((length=(token>>ML_BITS)) == RUN_MASK)  { size_t len; for (;(len=*ip++)==255;length+=255){} length += len; }

 

         // copy literals

         cpy = op+length;

@@ -727,27 +730,26 @@ int LZ4_uncompress(const char* source,
 

         // get offset

         LZ4_READ_LITTLEENDIAN_16(ref,cpy,ip); ip+=2;

-        if (ref < (BYTE* const)dest) goto _output_error;   // Error : offset create reference outside destination buffer

+        if unlikely(ref < (BYTE* const)dest) goto _output_error;   // Error : offset create reference outside destination buffer

 

         // get matchlength

         if ((length=(token&ML_MASK)) == ML_MASK) { for (;*ip==255;length+=255) {ip++;} length += *ip++; }

 

         // copy repeated sequence

-        if unlikely(op-ref<STEPSIZE)

+        if unlikely((op-ref)<STEPSIZE)

         {

 #if LZ4_ARCH64

-            size_t dec2table[]={0, 0, 0, -1, 0, 1, 2, 3};

-            size_t dec2 = dec2table[op-ref];

+            size_t dec64 = dec64table[op-ref];

 #else

-            const int dec2 = 0;

+            const int dec64 = 0;

 #endif

-            *op++ = *ref++;

-            *op++ = *ref++;

-            *op++ = *ref++;

-            *op++ = *ref++;

-            ref -= dec[op-ref];

-            A32(op)=A32(ref); op += STEPSIZE-4;

-            ref -= dec2;

+			op[0] = ref[0];

+            op[1] = ref[1];

+            op[2] = ref[2];

+            op[3] = ref[3];

+            op += 4, ref += 4; ref -= dec32table[op-ref];

+            A32(op) = A32(ref); 

+			op += STEPSIZE-4; ref -= dec64;

         } else { LZ4_COPYSTEP(ref,op); }

         cpy = op + length - (STEPSIZE-4);

         if (cpy>oend-COPYLENGTH)

@@ -787,14 +789,17 @@ int LZ4_uncompress_unknownOutputSize(
     BYTE* const oend = op + maxOutputSize;

     BYTE* cpy;

 

-    size_t dec[] ={0, 3, 2, 3, 0, 0, 0, 0};

+    size_t dec32table[] = {0, 3, 2, 3, 0, 0, 0, 0};

+#if LZ4_ARCH64

+    size_t dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};

+#endif

 

 

     // Main Loop

     while (ip<iend)

     {

-        BYTE token;

-        int length;

+        unsigned token;

+        size_t length;

 

         // get runlength

         token = *ip++;

@@ -808,7 +813,6 @@ int LZ4_uncompress_unknownOutputSize(
             if (ip+length != iend) goto _output_error;   // Error : LZ4 format requires to consume all input at this stage

             memcpy(op, ip, length);

             op += length;

-            ip = iend;

             break;                                       // Necessarily EOF, due to parsing restrictions

         }

         LZ4_WILDCOPY(ip, op, cpy); ip -= (op-cpy); op = cpy;

@@ -824,18 +828,17 @@ int LZ4_uncompress_unknownOutputSize(
         if unlikely(op-ref<STEPSIZE)

         {

 #if LZ4_ARCH64

-            size_t dec2table[]={0, 0, 0, -1, 0, 1, 2, 3};

-            size_t dec2 = dec2table[op-ref];

+            size_t dec64 = dec64table[op-ref];

 #else

-            const int dec2 = 0;

+            const int dec64 = 0;

 #endif

-            *op++ = *ref++;

-            *op++ = *ref++;

-            *op++ = *ref++;

-            *op++ = *ref++;

-            ref -= dec[op-ref];

-            A32(op)=A32(ref); op += STEPSIZE-4;

-            ref -= dec2;

+			op[0] = ref[0];

+            op[1] = ref[1];

+            op[2] = ref[2];

+            op[3] = ref[3];

+            op += 4, ref += 4; ref -= dec32table[op-ref];

+            A32(op) = A32(ref); 

+			op += STEPSIZE-4; ref -= dec64;

         } else { LZ4_COPYSTEP(ref,op); }

         cpy = op + length - (STEPSIZE-4);

         if (cpy>oend-COPYLENGTH)