gzip: optionally faster put_32bit()

function                                             old     new   delta
put_32bit                                             22      55     +33

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/archival/gzip.c b/archival/gzip.c
index 08633d667c1b8122e1ba20ef9bcc32e0e8b11856..5812f4b27735e66d138b2bfef77c071c8d685c14 100644 (file)
--- a/archival/gzip.c
+++ b/archival/gzip.c
@@ -454,7 +454,7 @@ static void put_16bit(ush w)
        if (outcnt < OUTBUFSIZ-2) {
                /* Common case */
                ush *dst16 = (void*) dst;
-               *dst16 = w; /* unalinged LSB 16-bit store */
+               *dst16 = w; /* unaligned LSB 16-bit store */
                G1.outcnt = outcnt + 2;
                return;
        }
@@ -480,6 +480,18 @@ static void put_16bit(ush w)
 
 static void put_32bit(ulg n)
 {
+#if CONFIG_GZIP_FAST > 0 \
+ && BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN
+       unsigned outcnt = G1.outcnt;
+       if (outcnt < OUTBUFSIZ-4) {
+               /* Common case */
+               uch *dst = &G1.outbuf[outcnt];
+               ulg *dst32 = (void*) dst;
+               *dst32 = n; /* unaligned LSB 32-bit store */
+               G1.outcnt = outcnt + 4;
+               return;
+       }
+#endif
        put_16bit(n);
        put_16bit(n >> 16);
 }
@@ -544,7 +556,7 @@ static void send_bits(unsigned value, unsigned length)
                 */
                value >>= (BUF_SIZE - G1.bi_valid);
                if (BUF_SIZE == 32) {
-                       put_32bit(new_buf); /* maybe unroll to 2*put_16bit()? */
+                       put_32bit(new_buf);
                } else { /* 16 */
                        put_16bit(new_buf);
                }