Fix handling of 16-byte quantities in endianness adjusted check-summing.

src/cksum.c

@@ -112,16 +112,17 @@ memcrc_r(uint32_t *state, const unsigned char *block, size_t block_len)
   *state = s;
 }
 
-#define SWAP_CSUM(BITWIDTH,BYTEWIDTH)                                   \
+#define SWAP_CSUM(BITWIDTH,BYTEWIDTH,NACC)                              \
   do {                                                                  \
     register const uint##BITWIDTH##_t *b = (uint##BITWIDTH##_t *)elems; \
     for (size_t i = 0; i < num_elems; ++i) {                            \
-      uint##BITWIDTH##_t accum = b[i];                                  \
-      for (size_t j = 0; j < BYTEWIDTH; ++j)                            \
-      {                                                                 \
-        uint32_t c = (uint32_t)(accum & UCHAR_MAX);                     \
-        s = (s << 8) ^ crctab[(s >> 24) ^ c];                           \
-        accum >>= 8;                                                    \
+      for(size_t aofs = NACC; aofs > 0; --aofs) {                       \
+        uint##BITWIDTH##_t accum = b[i + aofs - 1];                     \
+        for (size_t j = 0; j < BYTEWIDTH; ++j) {                        \
+          uint32_t c = (uint32_t)(accum & UCHAR_MAX);                   \
+          s = (s << 8) ^ crctab[(s >> 24) ^ c];                         \
+          accum >>= 8;                                                  \
+        }                                                               \
       }                                                                 \
     }                                                                   \
   } while (0)
@@ -148,16 +149,16 @@ memcrc_r_eswap(uint32_t *state, const unsigned char *elems, size_t num_elems,
     memcrc_r(state, elems, num_elems * elem_size);
     return;
   case 2:
-    SWAP_CSUM(16,2);
+    SWAP_CSUM(16,2,1);
     break;
   case 4:
-    SWAP_CSUM(32,4);
+    SWAP_CSUM(32,4,1);
     break;
   case 8:
-    SWAP_CSUM(64,8);
+    SWAP_CSUM(64,8,1);
     break;
   case 16:
-    SWAP_CSUM(64,8);
+    SWAP_CSUM(64,8,2);
     break;
   }
   *state = s;
@@ -182,3 +183,13 @@ memcrc_finish(uint32_t *state, off_t total_size)
 
   return ~s;
 }
+
+/*
+ * Local Variables:
+ * c-file-style: "Java"
+ * c-basic-offset: 2
+ * indent-tabs-mode: nil
+ * show-trailing-whitespace: t
+ * require-trailing-newline: t
+ * End:
+ */