4 files changed, 56 insertions, 1 deletions
diff --git a/Makefile b/Makefile
index 5d2ed5d..1d88ef2 100644
--- a/Makefile
+++ b/Makefile
@@ -1 +1 @@
-unpack_test: unpack_test.o unpack.o common.o
+unpack_test: unpack_test.o unpack.o common.o trace.o
diff --git a/pack.h b/pack.h
index 7a8fc69..ec8cf63 100644
--- a/pack.h
+++ b/pack.h
@@ -9,6 +9,13 @@ enum pack_status {
 	PACK_TOOSMALL,
 };
 
+extern enum pack_trace {
+	PACK_TRACE_OFF,
+	PACK_TRACE_CALL,
+	PACK_TRACE_DEBUG,
+	PACK_TRACE_ALL,
+} pack_trace;
+
 enum pack_status unpack(void *buf, size_t size, const char *fmt, ...);
 
 const char *pack_strerror(enum pack_status status);
diff --git a/trace.c b/trace.c
new file mode 100644
index 0000000..456d277
--- /dev/null
+++ b/trace.c
@@ -0,0 +1,41 @@
+#include <stdarg.h>
+#include <stdio.h>
+
+#include "pack.h"
+#include "trace.h"
+
+enum pack_trace pack_trace = PACK_TRACE_OFF;
+
+void trace(enum pack_trace level, const char *fmt, va_list va)
+{
+	char *type;
+
+	if (level > pack_trace) return;
+
+	switch (level) {
+	case PACK_TRACE_CALL: type = "CALL"; break;
+	case PACK_TRACE_DEBUG: type = "DEBUG"; break;
+	}
+
+	fprintf(stderr, "PACK_TRACE_%s: ", type);
+	vfprintf(stderr, fmt, va);
+	fputc('\n', stderr);
+}
+
+void tr_call(const char *fmt, ...)
+{
+	va_list va;
+
+	va_start(va, fmt);
+	trace(PACK_TRACE_CALL, fmt, va);
+	va_end(va);
+}
+
+void tr_debug(const char *fmt, ...)
+{
+	va_list va;
+
+	va_start(va, fmt);
+	trace(PACK_TRACE_DEBUG, fmt, va);
+	va_end(va);
+}
diff --git a/trace.h b/trace.h
new file mode 100644
index 0000000..cf631cc
--- /dev/null
+++ b/trace.h
@@ -0,0 +1,7 @@
+#ifndef PACK_TRACE_H
+#define PACK_TRACE_H
+
+void tr_call(const char *fmt, ...);
+void tr_debug(const char *fmt, ...);
+
+#endif // !PACK_TRACE_H