xfs_db: hoist bit scraping function

Hoist the bit scraping code into a separate helper function so that we
can create a _le version later, and also enable some testing functions.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

diff --git a/db/bit.c b/db/bit.c
index 1b9ca054f3b1e6357c6e1e19211c3c14157aae3d..26c3ed2ce7322238a395f8f58df015fb66028c2d 100644 (file)
--- a/db/bit.c
+++ b/db/bit.c
@@ -22,6 +22,48 @@ getbit_l(
        return (*ptr & mask) >> shift;
 }
 
+/*
+ * Extract a big-endian integer value from some bits in the middle of a buffer
+ * and return it as an int64_t in host-endian format.
+ *
+ * @p points to the start of the buffer
+ * @bit is the bit offset beyond @p
+ * @nbits is the number of bits to extract
+ * @signext enables sign extension of the return value
+ */
+static int64_t
+scrape_bits_be(
+       char    *p,
+       int     nbits,
+       int     bit,
+       bool    signext)
+{
+       int     i;
+       int64_t rval = 0LL;
+
+       for (i = 0; i < nbits; i++) {
+               if (getbit_l(p, bit + i)) {
+                       /* If the last bit is on and we care about sign bits
+                        * and we don't have a full 64 bit container, turn all
+                        * bits on between the sign bit and the most sig bit.
+                        */
+
+                       /* handle endian swap here */
+#if __BYTE_ORDER == LITTLE_ENDIAN
+                       if (i == 0 && signext && nbits < 64)
+                               rval = (~0ULL) << nbits;
+                       rval |= 1ULL << (nbits - i - 1);
+#else
+                       if ((i == (nbits - 1)) && signext && nbits < 64)
+                               rval |= ((~0ULL) << nbits);
+                       rval |= 1ULL << (nbits - i - 1);
+#endif
+               }
+       }
+
+       return rval;
+}
+
 void
 setbit_l(
        char *ptr,
@@ -51,9 +93,7 @@ getbitval(
        int             flags)
 {
        int             bit;
-       int             i;
        char            *p;
-       int64_t         rval;
        int             signext;
 
        ASSERT(nbits<=64);
@@ -83,27 +123,7 @@ getbitval(
        }
 
 scrape_bits:
-       for (i = 0, rval = 0LL; i < nbits; i++) {
-               if (getbit_l(p, bit + i)) {
-                       /* If the last bit is on and we care about sign
-                        * bits and we don't have a full 64 bit
-                        * container, turn all bits on between the
-                        * sign bit and the most sig bit.
-                        */
-
-                       /* handle endian swap here */
-#if __BYTE_ORDER == LITTLE_ENDIAN
-                       if (i == 0 && signext && nbits < 64)
-                               rval = (~0ULL) << nbits;
-                       rval |= 1ULL << (nbits - i - 1);
-#else
-                       if ((i == (nbits - 1)) && signext && nbits < 64)
-                               rval |= ((~0ULL) << nbits);
-                       rval |= 1ULL << (nbits - i - 1);
-#endif
-               }
-       }
-       return rval;
+       return scrape_bits_be(p, nbits, bit, signext);
 }
 
 /*