From 397d50664ae8c35c8affcc482f2d196e7983cfb8 Mon Sep 17 00:00:00 2001
From: Frank Denis <github@pureftpd.org>
Date: Mon, 16 Nov 2015 22:14:27 +0100
Subject: [PATCH] Faster sodium_is_zero() and sodium_increment() helpers Also
 add sodium_add(), since people tend to reimplement this in order to add
 constants to nonces.

---
 src/libsodium/include/sodium/utils.h |  3 ++
 src/libsodium/sodium/utils.c         | 58 ++++++++++++++++++++++------
 2 files changed, 50 insertions(+), 11 deletions(-)

diff --git a/src/libsodium/include/sodium/utils.h b/src/libsodium/include/sodium/utils.h
index e61f9b34..5fec3ec6 100644
--- a/src/libsodium/include/sodium/utils.h
+++ b/src/libsodium/include/sodium/utils.h
@@ -46,6 +46,9 @@ int sodium_is_zero(const unsigned char *n, const size_t nlen);
 SODIUM_EXPORT
 void sodium_increment(unsigned char *n, const size_t nlen);
 
+SODIUM_EXPORT
+void sodium_add(unsigned char *a, const unsigned char *b, const size_t len);
+
 SODIUM_EXPORT
 char *sodium_bin2hex(char * const hex, const size_t hex_maxlen,
                      const unsigned char * const bin, const size_t bin_len);
diff --git a/src/libsodium/sodium/utils.c b/src/libsodium/sodium/utils.c
index a032219e..fd629e13 100644
--- a/src/libsodium/sodium/utils.c
+++ b/src/libsodium/sodium/utils.c
@@ -157,25 +157,61 @@ sodium_compare(const unsigned char *b1_, const unsigned char *b2_, size_t len)
 int
 sodium_is_zero(const unsigned char *n, const size_t nlen)
 {
-    size_t        i;
-    unsigned char c = 0U;
-
-    for (i = (size_t) 0U; i < nlen; i++) {
+    size_t        i = 0U;
+#if !defined(CPU_UNALIGNED_ACCESS) || !defined(NATIVE_LITTLE_ENDIAN)
+    uint_fast8_t  c = 0U;
+#else
+    uint_fast64_t c = 0U;
+    for (; i < (nlen & ~0x7); i += 8U) {
+        c |= *((const uint64_t *) (const void *) &n[i]);
+    }
+#endif
+    for (; i < nlen; i++) {
         c |= n[i];
     }
-    return ((c - 1U) >> 8) & 1U;
+    return (int) (((c - 1U) >> 8) & 1U);
 }
 
 void
 sodium_increment(unsigned char *n, const size_t nlen)
 {
-    size_t       i;
-    unsigned int c = 1U << 8;
-
-    for (i = (size_t) 0U; i < nlen; i++) {
-        c >>= 8;
-        c += n[i];
+    size_t        i = 0U;
+#if !defined(CPU_UNALIGNED_ACCESS) || !defined(NATIVE_LITTLE_ENDIAN)
+    uint_fast16_t c = 1U;
+#else
+    uint_fast64_t c = 1U;
+    for (; i < (nlen & ~0x3); i += 4U) {
+        c += (uint_fast64_t) *((const uint32_t *) (const void *) &n[i]);
+        *((uint32_t *) (void *) &n[i]) = (uint32_t) c;
+        c >>= 32;
+    }
+#endif
+    for (; i < nlen; i++) {
+        c += (uint_fast16_t) n[i];
         n[i] = (unsigned char) c;
+        c >>= 8;
+    }
+}
+
+void
+sodium_add(unsigned char *a, const unsigned char *b, const size_t len)
+{
+    size_t        i = 0U;
+#if !defined(CPU_UNALIGNED_ACCESS) || !defined(NATIVE_LITTLE_ENDIAN)
+    uint_fast16_t c = 0U;
+#else
+    uint_fast64_t c = 0U;
+    for (; i < (len & ~0x3); i += 4U) {
+        c += (uint_fast64_t) *((const uint32_t *) (const void *) &a[i]) +
+             (uint_fast64_t) *((const uint32_t *) (const void *) &b[i]);
+        *((uint32_t *) (void *) &a[i]) = (uint32_t) c;
+        c >>= 32;
+    }
+#endif
+    for (; i < len; i++) {
+        c += (uint_fast16_t) a[i] + (uint_fast16_t) b[i];
+        a[i] = (unsigned char) c;
+        c >>= 8;
     }
 }