20060303

1 files changed, 44 insertions, 0 deletions

diff --git a/os/boot/pc/queue.c b/os/boot/pc/queue.c
new file mode 100644
index 00000000..d2a529cd
--- /dev/null
+++ b/os/boot/pc/queue.c
@@ -0,0 +1,44 @@
+#include	"u.h"
+#include	"lib.h"
+#include	"mem.h"
+#include	"dat.h"
+#include	"fns.h"
+#include	"io.h"
+
+int
+qgetc(IOQ *q)
+{
+	int c;
+
+	if(q->in == q->out)
+		return -1;
+	c = *q->out;
+	if(q->out == q->buf+sizeof(q->buf)-1)
+		q->out = q->buf;
+	else
+		q->out++;
+	return c;
+}
+
+static int
+qputc(IOQ *q, int c)
+{
+	uchar *nextin;
+	if(q->in >= &q->buf[sizeof(q->buf)-1])
+		nextin = q->buf;
+	else
+		nextin = q->in+1;
+	if(nextin == q->out)
+		return -1;
+	*q->in = c;
+	q->in = nextin;
+	return 0;
+}
+
+void
+qinit(IOQ *q)
+{
+	q->in = q->out = q->buf;
+	q->getc = qgetc;
+	q->putc = qputc;
+}