diff --git a/c/debug.c b/c/debug.c
index 0a2635e..ac1d2a6 100644
--- a/c/debug.c
+++ b/c/debug.c
@@ -19,12 +19,13 @@
 #define DEBUG_DEBUG
 #endif
 
+#include "bits.h"
 #include "debug.h"
 
 #define NANOSEC  1000000000                       /* nano sec in sec */
 #define MILLISEC 1000000                          /* milli sec in sec */
 
-static s64 timer_start;                           /* in nanosecond */
+static long long timer_start;                     /* in nanosecond */
 static u32 debug_level=0;
 
 void debug_level_set(u32 level)
@@ -48,7 +49,7 @@ void debug_init(u32 level)
     log(0, "timer started.\n");
 }
 
-inline static s64 timer_elapsed()
+inline static long long timer_elapsed()
 {
     struct timespec timer;
 
@@ -56,7 +57,6 @@ inline static s64 timer_elapsed()
     return (timer.tv_sec * NANOSEC + timer.tv_nsec) - timer_start;
 }
 
-
 /* void debug - log function
  * @timestamp : boolean
  * @indent    : indent level (2 spaces each)
@@ -75,9 +75,9 @@ void debug(u32 level, bool timestamp, u32 indent, const char *src,
         printf("%*s", 2*(indent-1), "");
 
     if (timestamp) {
-        s64 diff = timer_elapsed();
-        printf("%ld.%03ld ", diff/NANOSEC, (diff/1000000)%1000);
-        printf("%010ld ", diff);
+        long long diff = timer_elapsed();
+        printf("%lld.%03lld ", diff/NANOSEC, (diff/1000000)%1000);
+        printf("%010lld ", diff);
     }
 
     if (src) {
diff --git a/c/include/bits.h b/c/include/bits.h
index 31db90a..85d6ea0 100644
--- a/c/include/bits.h
+++ b/c/include/bits.h
@@ -25,10 +25,10 @@
 #endif
 
 /* no plan to support 32bits for now...
+ * #if __WORDSIZE != 64
+ * #error "Only 64 bits word size supported."
+ * #endif
  */
-#if __WORDSIZE != 64
-#error "Only 64 bits word size supported."
-#endif
 
 /* fixed-size types
  */
@@ -73,6 +73,27 @@ static __always_inline int popcount64(u64 n)
 #   endif
 }
 
+static __always_inline int popcount32(u32 n)
+{
+#   if __has_builtin(__builtin_popcount)
+#   ifdef DEBUG_BITS
+    log_f(1, "builtin.\n");
+#   endif
+    return __builtin_popcount(n);
+
+#   else
+#   ifdef DEBUG_BITS
+    log_f(1, "emulated.\n");
+#   endif
+    int count = 0;
+    while (n) {
+        count++;
+        n &= (n - 1);
+    }
+    return count;
+#   endif
+}
+
 /* char is a special case, as it can be signed or unsigned
  */
 typedef signed char schar;
@@ -242,27 +263,6 @@ static __always_inline uint ffs32(u32 n)
 #   endif
 }
 
-static __always_inline int popcount32(u32 n)
-{
-#   if __has_builtin(__builtin_popcount)
-#   ifdef DEBUG_BITS
-    log_f(1, "builtin.\n");
-#   endif
-    return __builtin_popcount(n);
-
-#   else
-#   ifdef DEBUG_BITS
-    log_f(1, "emulated.\n");
-#   endif
-    int count = 0;
-    while (n) {
-        count++;
-        n &= (n - 1);
-    }
-    return count;
-#   endif
-}
-
 /*  rolXX are taken from kernel's <linux/bitops.h> are are:
  * SPDX-License-Identifier: GPL-2.0
  */