util: Introduce virReadBufInt16LE and virReadBufInt16BE

In order to read 16 bits of data in the native format and convert add
the 16 bit macros to match existing 32 and 64 bit code.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/util/virendian.h

@@ -90,4 +90,28 @@
      ((uint32_t)(uint8_t)((buf)[2]) << 16) |             \
      ((uint32_t)(uint8_t)((buf)[3]) << 24))
 
+/**
+ * virReadBufInt16BE:
+ * @buf: byte to start reading at (can be 'char*' or 'unsigned char*');
+ *       evaluating buf must not have any side effects
+ *
+ * Read 2 bytes at BUF as a big-endian 16-bit number.  Caller is
+ * responsible to avoid reading beyond array bounds.
+ */
+# define virReadBufInt16BE(buf)                          \
+    (((uint16_t)(uint8_t)((buf)[0]) << 8) |              \
+     (uint16_t)(uint8_t)((buf)[1]))
+
+/**
+ * virReadBufInt16LE:
+ * @buf: byte to start reading at (can be 'char*' or 'unsigned char*');
+ *       evaluating buf must not have any side effects
+ *
+ * Read 2 bytes at BUF as a little-endian 16-bit number.  Caller is
+ * responsible to avoid reading beyond array bounds.
+ */
+# define virReadBufInt16LE(buf)                          \
+    ((uint16_t)(uint8_t)((buf)[0]) |                     \
+     ((uint16_t)(uint8_t)((buf)[1]) << 8))
+
 #endif /* __VIR_ENDIAN_H__ */

tests/virendiantest.c

@@ -50,6 +50,15 @@ test1(const void *data ATTRIBUTE_UNUSED)
     if (virReadBufInt32LE(array + 9) != 0x8d8c8b8aU)
         goto cleanup;
 
+    if (virReadBufInt16BE(array) != 0x0102U)
+        goto cleanup;
+    if (virReadBufInt16BE(array + 11) != 0x8c8dU)
+        goto cleanup;
+    if (virReadBufInt16LE(array) != 0x0201U)
+        goto cleanup;
+    if (virReadBufInt16LE(array + 11) != 0x8d8cU)
+        goto cleanup;
+
     ret = 0;
  cleanup:
     return ret;
@@ -81,6 +90,15 @@ test2(const void *data ATTRIBUTE_UNUSED)
     if (virReadBufInt32LE(array + 9) != 0x8d8c8b8aU)
         goto cleanup;
 
+    if (virReadBufInt16BE(array) != 0x0102U)
+        goto cleanup;
+    if (virReadBufInt16BE(array + 11) != 0x8c8dU)
+        goto cleanup;
+    if (virReadBufInt16LE(array) != 0x0201U)
+        goto cleanup;
+    if (virReadBufInt16LE(array + 11) != 0x8d8cU)
+        goto cleanup;
+
     ret = 0;
  cleanup:
     return ret;