4 files changed, 84 insertions, 0 deletions
diff --git a/com32/include/dprintf.h b/com32/include/dprintf.h
new file mode 100644
index 00000000..4c9682c0
--- /dev/null
+++ b/com32/include/dprintf.h
@@ -0,0 +1,22 @@
+/*
+ * dprintf.h
+ */
+
+#ifndef _DPRINTF_H
+#define _DPRINTF_H
+
+#ifdef DEBUG
+
+#include <stdio.h>
+
+int dprintf(const char *, ...);
+int vdprintf(const char *, va_list);
+
+#else
+
+#define dprintf(fmt, ...)	((void)(0))
+#define vdprintf(fmt, ap)	((void)(0))
+
+#endif /* DEBUG */
+
+#endif /* _DPRINTF_H */
diff --git a/com32/lib/Makefile b/com32/lib/Makefile
index 3a9eafd6..f1e2680f 100644
--- a/com32/lib/Makefile
+++ b/com32/lib/Makefile
@@ -27,6 +27,8 @@ LIBOBJS = \
 	asprintf.o vasprintf.o strlcpy.o strlcat.o			\
 	vsscanf.o zalloc.o						\
 	\
+	dprintf.o vdprintf.o						\
+	\
 	opendir.o readdir.o closedir.o getcwd.o chdir.o fdopendir.o	\
 	\
 	libgcc/__ashldi3.o libgcc/__udivdi3.o			\
diff --git a/com32/lib/dprintf.c b/com32/lib/dprintf.c
new file mode 100644
index 00000000..96170237
--- /dev/null
+++ b/com32/lib/dprintf.c
@@ -0,0 +1,17 @@
+/*
+ * dprintf.c
+ */
+
+#include <stdio.h>
+#include <stdarg.h>
+
+int dprintf(const char *format, ...)
+{
+    va_list ap;
+    int rv;
+
+    va_start(ap, format);
+    rv = vdprintf(stdout, format, ap);
+    va_end(ap);
+    return rv;
+}
diff --git a/com32/lib/vdprintf.c b/com32/lib/vdprintf.c
new file mode 100644
index 00000000..46a4b00d
--- /dev/null
+++ b/com32/lib/vdprintf.c
@@ -0,0 +1,43 @@
+/*
+ * vdprintf.c
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <inttypes.h>
+#include <sys/io.h>
+
+#define BUFFER_SIZE	32768
+
+struct file_info;
+extern ssize_t __serial_write(struct file_info *, const void *, size_t);
+
+static const uint16_t debug_base = 0x03f8; /* I/O base address */
+
+int vdprintf(const char *format, va_list ap)
+{
+    int rv;
+    char buffer[BUFFER_SIZE];
+    char *p;
+
+    rv = vsnprintf(buffer, BUFFER_SIZE, format, ap);
+
+    if (rv < 0)
+	return rv;
+
+    if (rv > BUFFER_SIZE - 1)
+	rv = BUFFER_SIZE - 1;
+
+    /*
+     * This unconditionally outputs to a serial port at 0x3f8 regardless of
+     * if one is enabled or not (this means we don't have to enable the real
+     * serial console and therefore get conflicting output.)
+     */
+    while (rv--) {
+	while ((inb(debug_base+5) & 0x20) == 0)
+	    ;
+	outb(*p++, debug_base);
+    }
+}