[GitHub] [incubator-nuttx] hartmannathan commented on a diff in pull request #6920: support /dev/crypto for nuttx

[GitBox <gi...@apache.org>]

hartmannathan commented on code in PR #6920:
URL: https://github.com/apache/incubator-nuttx/pull/6920#discussion_r998894368


##########
crypto/chacha_private.h:
##########
@@ -0,0 +1,335 @@
+/****************************************************************************
+ * crypto/chacha_private.h
+ * $OpenBSD: chacha_private.h,v 1.4 2020/07/22 13:54:30 tobhe Exp $
+ *
+ * chacha-merged.c version 20080118
+ * D. J. Bernstein
+ * Public domain.
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <string.h>
+#include <sys/types.h>
+
+typedef uint8_t u8;
+typedef uint32_t u32;
+
+typedef struct
+{
+  u32 input[16]; /* could be compressed */
+}
+chacha_ctx;
+
+#define U8C(v) (v##U)
+#define U32C(v) (v##U)
+
+#define U8V(v) ((u8)(v) & U8C(0xFF))
+#define U32V(v) ((u32)(v) & U32C(0xFFFFFFFF))
+
+#define ROTL32(v, n) \
+  (U32V((v) << (n)) | ((v) >> (32 - (n))))
+
+#define U8TO32_LITTLE(p) \
+  (((u32)((p)[0])) | \
+   ((u32)((p)[1]) << 8) | \
+   ((u32)((p)[2]) << 16) | \
+   ((u32)((p)[3]) << 24))
+
+#define U32TO8_LITTLE(p, v) \
+  do { \
+    (p)[0] = U8V((v)); \
+    (p)[1] = U8V((v) >> 8); \
+    (p)[2] = U8V((v) >> 16); \
+    (p)[3] = U8V((v) >> 24); \
+  } while (0)
+
+#define ROTATE(v, c) (ROTL32(v, c))
+#define XOR(v, w) ((v) ^ (w))
+#define PLUS(v, w) (U32V((v) + (w)))
+#define PLUSONE(v) (PLUS((v), 1))
+
+#define QUARTERROUND(a, b, c, d) \

Review Comment:
   Ditto. Best to wrap multiple statements with `do { ... } while (0)`, else if this macro is used like the following example:
   
   ```
   if (condition)
     QUARTERROUND(a, b, c, d);
   
   other_code();
   ```
   
   that would lead to unexpected results!
   



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