Use an explicit table for tolower() to avoid a function call

On some platforms, tolower() is implemented as a function call, in
order to handle locale support.  We never change locales, so can the
result of tolower() into a table, so we don't have to sit through the
function call every time.

~1.3% overall performance improvement on a macro-heavy benchmark under
Linux x86-64.

1 files changed, 2 insertions, 4 deletions

diff --git a/crc64.c b/crc64.c
index fc165b7..e8639c8 100644
--- a/crc64.c
+++ b/crc64.c
@@ -1,6 +1,5 @@
 #include "compiler.h"
-#include <inttypes.h>
-#include <ctype.h>
+#include "nasmlib.h"
 
 static const uint64_t crc64_tab[256] = {
     UINT64_C(0x0000000000000000), UINT64_C(0x7ad870c830358979),
@@ -149,8 +148,7 @@ uint64_t crc64i(uint64_t crc, const char *str)
     uint8_t c;
 
     while ((c = *str++) != 0) {
-	c = tolower(c);
-	crc = crc64_tab[(uint8_t)crc ^ c] ^ (crc >> 8);
+	crc = crc64_tab[(uint8_t)crc ^ nasm_tolower(c)] ^ (crc >> 8);
     }
 
     return crc;