speed improvements

Author: Laurence Bank

src/inffast.c

@@ -12,6 +12,16 @@
 #define ALLOWS_UNALIGNED
 #endif
 
+#if INTPTR_MAX == INT64_MAX
+#define REGISTER_WIDTH 64
+typedef uint64_t BIGUINT;
+typedef uint32_t SMALLUINT;
+#else
+#define REGISTER_WIDTH 32
+typedef uint32_t BIGUINT;
+typedef uint16_t SMALLUINT;
+#endif // native register size
+
 #ifdef ASMINF
 #  pragma message("Assembler code may have bugs -- use at your own risk")
 #else
@@ -68,7 +78,8 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
     unsigned whave;             /* valid bytes in the window */
     unsigned wnext;             /* window write index */
     unsigned char FAR *window;  /* allocated sliding window, if wsize != 0 */
-    unsigned long hold;         /* local strm->hold */
+    BIGUINT hold, tmpbits;         /* local strm->hold */
+//    unsigned long hold;         /* local strm->hold */
     unsigned bits;              /* local strm->bits */
     code const FAR *lcode;      /* local strm->lencode */
     code const FAR *dcode;      /* local strm->distcode */
@@ -105,11 +116,12 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
     /* decode literals and length/distances until end-of-block or not enough
        input data or output space */
     do {
-        if (bits < 15) {
+        if (bits < (REGISTER_WIDTH/2)) { // helps on 32 and 64-bit CPUs
 #ifdef ALLOWS_UNALIGNED
-            hold |= (*(uint16_t *)in << bits);
-            in += 2;
-            bits += 16;
+            tmpbits = *(SMALLUINT *)in;
+            hold |= (BIGUINT)(tmpbits << bits);
+            in += sizeof(SMALLUINT);
+            bits += (REGISTER_WIDTH / 2);
 #else
             hold += (unsigned long)(*in++) << bits;
             bits += 8;
@@ -133,20 +145,29 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
             len = (unsigned)(here.val);
             op &= 15;                           /* number of extra bits */
             if (op) {
+#if REGISTER_WIDTH == 32
                 if (bits < op) {
-                    hold += (unsigned long)(*in++) << bits;
+                    hold += (uint32_t)(*in++) << bits;
                     bits += 8;
                 }
+#endif
                 len += (unsigned)hold & ((1U << op) - 1);
                 hold >>= op;
                 bits -= op;
             }
             Tracevv((stderr, "inflate:         length %u\n", len));
-            if (bits < 15) {
+            if (bits < (REGISTER_WIDTH/2)) { // helps on 32 and 64-bit CPUs
+#ifdef UNALIGNED_OK
+                tmpbits = *(SMALLUINT *)in;
+                hold |= (BIGUINT)(tmpbits << bits);
+                in += sizeof(SMALLUINT);
+                bits += (REGISTER_WIDTH / 2);
+#else
                 hold += (unsigned long)(*in++) << bits;
                 bits += 8;
                 hold += (unsigned long)(*in++) << bits;
                 bits += 8;
+#endif
             }
             here = dcode[hold & dmask];
           dodist:
@@ -157,6 +178,7 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
             if (op & 16) {                      /* distance base */
                 dist = (unsigned)(here.val);
                 op &= 15;                       /* number of extra bits */
+#if REGISTER_WIDTH == 32
                 if (bits < op) {
 #ifdef ALLOWS_UNALIGNED
                     hold |= (*(uint16_t *)in << bits);
@@ -171,6 +193,7 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
                     }
 #endif // ALLOWS_UNALIGNED
                 }
+#endif // 32-bit CPU
                 dist += (unsigned)hold & ((1U << op) - 1);
 #ifdef INFLATE_STRICT
                 if (dist > dmax) {
@@ -348,10 +371,10 @@ unsigned start;         /* inflate()'s starting value for strm->avail_out */
     } while (in < last && out < end);
 
     /* return unused bytes (on entry, bits < 8, so in won't go too far back) */
-    len = bits >> 3;
-    in -= len;
-    bits -= len << 3;
-    hold &= (1U << bits) - 1;
+//    len = bits >> 3;
+//    in -= len;
+//    bits -= len << 3;
+//    hold &= (1 << bits) - 1;
 
     /* update state and return */
     strm->next_in = in;

src/inflate.c

@@ -266,7 +266,8 @@ int value;
         state->bits = 0;
         return Z_OK;
     }
-    if (bits > 16 || state->bits + (uInt)bits > 32) return Z_STREAM_ERROR;
+    if (bits > 16 || state->bits + (uInt)bits > 32)
+        return Z_STREAM_ERROR;
     value &= (1L << bits) - 1;
     state->hold += (unsigned)value << state->bits;
     state->bits += (uInt)bits;

src/inflate.h

@@ -98,7 +98,8 @@ struct inflate_state {
     unsigned wnext;             /* window write index */
     unsigned char FAR *window;  /* allocated sliding window, if needed */
         /* bit accumulator */
-    unsigned long hold;         /* input bit accumulator */
+    uint64_t hold;         /* input bit accumulator */
+//    unsigned long hold;         /* input bit accumulator */
     unsigned bits;              /* number of bits in "in" */
         /* for string and stored block copying */
     unsigned length;            /* literal or length of data to copy */