From 9f82aac8cecbe3c44ba5ae56862c0a69b0a1a779 Mon Sep 17 00:00:00 2001
From: Dmitry Podgorny <pasis.ua@gmail.com>
Date: Sat, 25 Oct 2014 16:37:21 +0300
Subject: [PATCH] sha1: compile-time endianness check for some compilers

Newer gcc and clang provide macro __BYTE_ORDER__.
---
 src/sha1.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/sha1.c b/src/sha1.c
index 84a6b7e..9af4f04 100644
--- a/src/sha1.c
+++ b/src/sha1.c
@@ -124,11 +124,22 @@ void SHAPrintContext(SHA1_CTX *context, char *msg){
 
 static uint32_t host_to_be(uint32_t i)
 {
+#define le_to_be(i) ((rol((i),24) & 0xFF00FF00) | (rol((i),8) & 0x00FF00FF))
+#if defined(__BIG_ENDIAN__) || \
+    (defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && \
+    __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
+    return i;
+#elif defined(__LITTLE_ENDIAN__) || \
+      (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \
+      __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
+    return le_to_be(i);
+#else /* fallback to run-time check */
     static const union {
-        unsigned u;
+        uint32_t u;
         unsigned char c;
     } check = {1};
-    return check.c ? (rol(i,24)&0xFF00FF00)|(rol(i,8)&0x00FF00FF) : i;
+    return check.c ? le_to_be(i) : i;
+#endif
 }
 
 /* Hash a single 512-bit block. This is the core of the algorithm. */