diff --git a/src/debug.c b/src/debug.c
new file mode 100644
index 0000000..5546d08
--- /dev/null
+++ b/src/debug.c
@@ -0,0 +1,96 @@
+/* debug.c - debug/log management
+ *
+ * Copyright (C) 2021 Bruno Raoult ("br")
+ * Licensed under the GNU General Public License v3.0 or later.
+ * Some rights reserved. See COPYING.
+ *
+ * You should have received a copy of the GNU General Public License along with this
+ * program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.htmlL>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
+ *
+ */
+
+//#ifdef DEBUG
+#include <stdio.h>
+#include <stdarg.h>
+#include <time.h>
+#include "debug.h"
+
+#define NANOSEC  1000000000                       /* nano sec in sec */
+#define MILLISEC 1000000                          /* milli sec in sec */
+
+static int64_t timer_start;                       /* in nanosecond */
+
+int clock_gettime(clockid_t clockid, struct timespec *tp);
+
+void debug_init()
+{
+    struct timespec timer;
+    if (!clock_gettime(CLOCK_MONOTONIC, &timer)) {
+        timer_start = timer.tv_sec * NANOSEC + timer.tv_nsec;
+    }
+    else {
+        timer_start = 0;
+    }
+    log("timer started.\n");
+}
+
+inline static int64_t timer_elapsed()
+{
+    struct timespec timer;
+
+    clock_gettime(CLOCK_MONOTONIC, &timer);
+    return (timer.tv_sec * NANOSEC + timer.tv_nsec) - timer_start;
+}
+
+
+/* void debug - log function
+ * @timestamp : boolean
+ * @indent    : indent level (2 spaces each)
+ * @src       : source filename (or NULL)
+ * @line      : line number
+ */
+void debug(bool timestamp, uint32_t indent, const char *src,
+           uint32_t line, const char *fmt, ...)
+{
+    va_list ap;
+
+    if (indent)
+        printf("%*s", 2*indent, "");
+
+    if (timestamp) {
+        int64_t diff = timer_elapsed();
+        printf("%ld.%03ld ", diff/NANOSEC, (diff/1000000)%1000);
+        printf("%010ld ", diff);
+    }
+
+    if (src) {
+        if (line)
+            printf("[%s:%u] ", src, line);
+        else {
+            printf("[%s] ", src);
+        }
+    }
+    va_start(ap, fmt);
+    vprintf(fmt, ap);
+    va_end(ap);
+}
+
+#ifdef DEBUGBIN
+#include <unistd.h>
+
+int main()
+{
+    int foo=1;
+    debug_init();
+
+    log("log=%d\n", foo++);
+    log_i(1, "log_i=%d\n", foo++);
+    log_i(2, "log_i=%d\n", foo++);
+    log_it(3, "log_it=%d\n", foo++);
+    log_f("log_f=%d\n", foo++);
+}
+#endif
+
+//#endif /* DEBUG_H */
diff --git a/src/debug.h b/src/debug.h
new file mode 100644
index 0000000..5fd4214
--- /dev/null
+++ b/src/debug.h
@@ -0,0 +1,54 @@
+/* move.h - debug/log management.
+ *
+ * Copyright (C) 2021 Bruno Raoult ("br")
+ * Licensed under the GNU General Public License v3.0 or later.
+ * Some rights reserved. See COPYING.
+ *
+ * You should have received a copy of the GNU General Public License along with this
+ * program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.htmlL>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
+ *
+ */
+
+#ifndef DEBUG_H
+#define DEBUG_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#ifdef DEBUG
+
+void debug_init(void);
+
+void debug(bool timestamp, uint32_t indent,
+           const char *src, uint32_t line, const char *, ...);
+
+/* format: func name, no indent, no timestamp
+ * foo:15 val=2
+ */
+#define log(fmt, args...) debug(false, 0, __func__, __LINE__, fmt, ##args)
+
+/* format : func name, indent, no timestamp
+ *   foo:15 val=2
+ */
+#define log_i(i, fmt, args...) debug(false, (i), __func__, __LINE__, fmt, args)
+
+/* format : func name, indent, timestamp
+ *   []foo:15 val=2
+ */
+#define log_it(i, fmt, args...) debug(true, (i), __func__, __LINE__, fmt, args)
+
+/* format: file name, no indent, no timestamp
+ * foo:15 val=2
+ */
+#define log_f(fmt, args...) debug(false, 0, __FILE__, __LINE__, fmt, args)
+
+
+
+#else
+#define log(...)
+#define f
+#endif  /* DEBUG */
+
+#endif  /* DEBUG_H */