libbb/sha: do not read shaNI variable twice, and factor out its setting

My gcc inlines both calls, so instead of "-20 bytes" I get only this:

function                                             old     new   delta
sha256_begin                                          84      83      -1
sha1_begin                                           114     111      -3
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-4)               Total: -4 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 16 insertions, 12 deletions

diff --git a/libbb/hash_md5_sha.c b/libbb/hash_md5_sha.c
index bbe58c77b..88baf51dc 100644
--- a/libbb/hash_md5_sha.c
+++ b/libbb/hash_md5_sha.c
@@ -23,6 +23,14 @@ static void cpuid(unsigned *eax, unsigned *ebx, unsigned *ecx, unsigned *edx)
         );
 }
 static smallint shaNI;
+static int get_shaNI(void)
+{
+        unsigned eax = 7, ebx = ebx, ecx = 0, edx = edx;
+        cpuid(&eax, &ebx, &ecx, &edx);
+        ebx = ((ebx >> 28) & 2) - 1; /* bit 29 -> 1 or -1 */
+        shaNI = (int)ebx;
+        return (int)ebx;
+}
 void FAST_FUNC sha1_process_block64_shaNI(sha1_ctx_t *ctx);
 void FAST_FUNC sha256_process_block64_shaNI(sha256_ctx_t *ctx);
 #  if defined(__i386__)
@@ -1175,12 +1183,10 @@ void FAST_FUNC sha1_begin(sha1_ctx_t *ctx)
 #if ENABLE_SHA1_HWACCEL
 # if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
         {
-                if (!shaNI) {
-                        unsigned eax = 7, ebx = ebx, ecx = 0, edx = edx;
-                        cpuid(&eax, &ebx, &ecx, &edx);
-                        shaNI = ((ebx >> 28) & 2) - 1; /* bit 29 -> 1 or -1 */
-                }
-                if (shaNI > 0)
+                int ni = shaNI;
+                if (!ni)
+                        ni = get_shaNI();
+                if (ni > 0)
                         ctx->process_block = sha1_process_block64_shaNI;
         }
 # endif
@@ -1229,12 +1235,10 @@ void FAST_FUNC sha256_begin(sha256_ctx_t *ctx)
 #if ENABLE_SHA256_HWACCEL
 # if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
         {
-                if (!shaNI) {
-                        unsigned eax = 7, ebx = ebx, ecx = 0, edx = edx;
-                        cpuid(&eax, &ebx, &ecx, &edx);
-                        shaNI = ((ebx >> 28) & 2) - 1; /* bit 29 -> 1 or -1 */
-                }
-                if (shaNI > 0)
+                int ni = shaNI;
+                if (!ni)
+                        ni = get_shaNI();
+                if (ni > 0)
                         ctx->process_block = sha256_process_block64_shaNI;
         }
 # endif