gzip: optionally faster put_32bit()

function                                             old     new   delta
put_32bit                                             22      55     +33

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

1 files changed, 14 insertions, 2 deletions

diff --git a/archival/gzip.c b/archival/gzip.c
index 08633d667..5812f4b27 100644
--- 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);
                 }