1 files changed, 86 insertions, 0 deletions
diff --git a/emb/pastilda/lib/crypto/handy.h b/emb/pastilda/lib/crypto/handy.h
new file mode 100644
index 0000000..a9b2d9d
--- /dev/null
+++ b/emb/pastilda/lib/crypto/handy.h
@@ -0,0 +1,86 @@
+#ifndef HANDY_H
+#define HANDY_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+/*
+ * Handy CPP defines and C inline functions.
+ */
+
+/* Evaluates to the number of items in array-type variable arr. */
+#define ARRAYCOUNT(arr) (sizeof arr / sizeof arr[0])
+
+/* Normal MIN/MAX macros.  Evaluate argument expressions only once. */
+#ifndef MIN
+  #define MIN(x, y) \
+    ({ typeof (x) __x = (x); \
+       typeof (y) __y = (y); \
+       __x < __y ? __x : __y; })
+#endif
+#ifndef MAX
+  #define MAX(x, y) \
+    ({ typeof (x) __x = (x); \
+       typeof (y) __y = (y); \
+       __x > __y ? __x : __y; })
+#endif
+
+/* Swap two values.  Uses GCC type inference magic. */
+#ifndef SWAP
+  #define SWAP(x, y) \
+    do { \
+      typeof (x) __tmp = (x); \
+      (x) = (y); \
+      (y) = __tmp; \
+    } while (0)
+#endif
+
+/** Stringify its argument. */
+#define STRINGIFY(x) STRINGIFY_(x)
+#define STRINGIFY_(x) #x
+
+/* Error handling macros.
+ *
+ * These expect a zero = success, non-zero = error convention.
+ */
+
+/** Error: return. 
+ *  
+ *  If the expression fails, return the error from this function. */
+#define ER(expr) do { typeof (expr) err_ = (expr); if (err_) return err_; } while (0)
+
+/** Error: goto.
+ *
+ *  If the expression fails, goto x_err.  Assumes defn of label
+ *  x_err and 'error_type err'. */
+#define EG(expr) do { err = (expr); if (err) goto x_err; } while (0)
+
+/** Like memset(ptr, 0, len), but not allowed to be removed by
+ *  compilers. */
+static inline void mem_clean(volatile void *v, size_t len)
+{
+  if (len)
+  {
+    memset((void *) v, 0, len);
+    (void) *((volatile uint8_t *) v);
+  }
+}
+
+/** Returns 1 if len bytes at va equal len bytes at vb, 0 if they do not.
+ *  Does not leak length of common prefix through timing. */
+static inline unsigned mem_eq(const void *va, const void *vb, size_t len)
+{
+  const volatile uint8_t *a = va;
+  const volatile uint8_t *b = vb;
+  uint8_t diff = 0;
+
+  while (len--)
+  {
+    diff |= *a++ ^ *b++;
+  }
+
+  return !diff;
+}
+
+#endif