improve buf_cmp and buf_cmp_mask helpers

Rewrite buf_cmp to use memcpy for bulk of comparison.  Add static
helper to perform comparison of trailing byte, which uses another
static helper to perform a maksed comparison.  The masked comparison
helper is used by the buf_cmp_mask to simplify its loop.
Improve types to use void *, unsigned, and return bool.

diff --git a/src/helper/binarybuffer.c b/src/helper/binarybuffer.c
index 0def9485530afd834cf956b71b4efd4926bd05b4..865d3a3725b10bda5af219836d73e64b1eb2ce43 100644 (file)
--- a/src/helper/binarybuffer.c
+++ b/src/helper/binarybuffer.c
@@ -65,52 +65,53 @@ uint8_t* buf_cpy(const uint8_t *from, uint8_t *to, int size)
        return to;
 }
 
-int buf_cmp(const uint8_t *buf1, const uint8_t *buf2, int size)
+static bool buf_cmp_masked(uint8_t a, uint8_t b, uint8_t m)
 {
-       if (!buf1 || !buf2)
-               return 1;
+       return (a & m) != (b & m);
+}
+static bool buf_cmp_trailing(uint8_t a, uint8_t b, uint8_t m, unsigned trailing)
+{
+       uint8_t mask = (1 << trailing) - 1;
+       return buf_cmp_masked(a, b, mask & m);
+}
 
-       for (unsigned i = 0, num_bytes = CEIL(size, 8); i < num_bytes; i++)
-       {
-               /* last byte */
-               /* mask out bits that don't really belong to the buffer if size isn't a multiple of 8 bits */
-               if ((size % 8) && (i == num_bytes -1))
-               {
-                       if ((buf1[i] & ((1 << (size % 8)) - 1)) != (buf2[i] & ((1 << (size % 8)) - 1)))
-                               return 1;
-               }
-               else
-               {
-                       if (buf1[i] != buf2[i])
-                               return 1;
-               }
-       }
+bool buf_cmp(const void *_buf1, const void *_buf2, unsigned size)
+{
+       if (!_buf1 || !_buf2)
+               return _buf1 != _buf2;
 
-       return 0;
+       unsigned last = size / 8;
+       if (memcmp(_buf1, _buf2, last) != 0)
+               return false;
+
+       unsigned trailing = size % 8;
+       if (!trailing)
+               return false;
+
+       const uint8_t *buf1 = _buf1, *buf2 = _buf2;
+       return buf_cmp_trailing(buf1[last], buf2[last], 0xff, trailing);
 }
 
-int buf_cmp_mask(const uint8_t *buf1, const uint8_t *buf2, const uint8_t *mask, int size)
+bool buf_cmp_mask(const void *_buf1, const void *_buf2,
+               const void *_mask, unsigned size)
 {
-       for (unsigned i = 0, num_bytes = CEIL(size, 8); i < num_bytes; i++)
+       if (!_buf1 || !_buf2)
+               return _buf1 != _buf2 || _buf1 != _mask;
+
+       const uint8_t *buf1 = _buf1, *buf2 = _buf2, *mask = _mask;
+       unsigned last = size / 8;
+       for (unsigned i = 0; i < last; i++)
        {
-               /* last byte */
-               /* mask out bits that don't really belong to the buffer if size isn't a multiple of 8 bits */
-               if ((size % 8) && (i == num_bytes -1))
-               {
-                       if ((buf1[i] & ((1 << (size % 8)) - 1) & mask[i]) !=
-                               (buf2[i] & ((1 << (size % 8)) - 1) & mask[i]))
-                               return 1;
-               }
-               else
-               {
-                       if ((buf1[i] & mask[i]) != (buf2[i] & mask[i]))
-                               return 1;
-               }
+               if (buf_cmp_masked(buf1[i], buf2[i], mask[i]))
+                       return true;
        }
-
-       return 0;
+       unsigned trailing = size % 8;
+       if (!trailing)
+               return false;
+       return buf_cmp_trailing(buf1[last], buf2[last], mask[last], trailing);
 }
 
+
 uint8_t* buf_set_ones(uint8_t *buf, int count)
 {
        for (unsigned i = 0, num_bytes = CEIL(count, 8); i < num_bytes; i++)

diff --git a/src/helper/binarybuffer.h b/src/helper/binarybuffer.h
index 49050074fb226cd6e82315152a9363b9362a64b9..a51c2e57846e94b785ac11ba5e9087decd9ad49e 100644 (file)
--- a/src/helper/binarybuffer.h
+++ b/src/helper/binarybuffer.h
@@ -70,9 +70,9 @@ static inline uint32_t buf_get_u32(const uint8_t* buffer,
 /// flip_u32 inverts the bit order inside a 32-bit word (31..0 -> 0..31)
 uint32_t flip_u32(uint32_t value, unsigned int num);
 
-int buf_cmp(const uint8_t *buf1, const uint8_t *buf2, int size);
-int buf_cmp_mask(const uint8_t *buf1, const uint8_t *buf2,
-               const uint8_t *mask, int size);
+bool buf_cmp(const void *buf1, const void *buf2, unsigned size);
+bool buf_cmp_mask(const void *buf1, const void *buf2,
+               const void *mask, unsigned size);
 uint8_t* buf_cpy(const uint8_t *from, uint8_t *to, int size);
 
 uint8_t* buf_set_ones(uint8_t *buf, int count);