1 files changed, 86 insertions, 0 deletions
diff --git a/kernel/tty.c b/kernel/tty.c
new file mode 100644
index 0000000..1946110
--- /dev/null
+++ b/kernel/tty.c
@@ -0,0 +1,86 @@
+#include <asm/interrupt.h>
+#include <errno.h>
+#include <kernel/sched.h>
+#include <kernel/serial.h>
+#include <kernel/tty.h>
+#include <limits.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#define NRTTY \
+  (sizeof(ttys) / sizeof(struct tty_struct*))
+
+static struct tty_struct *ttys[] = {
+  NULL,
+  &tty_rs
+};
+
+/* check if the buffer's empty and if so, go to sleep */
+static int sleep_while_empty(struct tty_queue *q) {
+  if(q->pread != q->pwrite)
+    return 0;
+
+  cli();
+  while(1) {
+    if(q->pread == q->pwrite)
+      interruptible_sleep_on(&q->waiting);
+
+    /* check again to see if anything was read, or we were interrupted */
+    if(q->pread == q->pwrite) {
+      sti();
+      return -1;
+    }
+
+    sti();
+    return 0;
+  }
+}
+
+ssize_t tty_read(unsigned tty, void *buf, size_t len) {
+  size_t i;
+  char *b = buf;
+  struct tty_queue *q = &ttys[tty]->rqueue;
+
+  if(tty > NRTTY || ttys[tty] == NULL)
+    return -1;
+
+  if(len == 0)
+    return 0;
+
+  if(len > SSIZE_MAX)
+    len = SSIZE_MAX;
+
+  for(i = 0; i < len; i++) {
+    /* check if the buffer's empty and if so, go to sleep */
+    if(sleep_while_empty(q) < 0) {
+      if(i == 0)
+        return -EINTR;
+
+      return i;
+    }
+
+    *b++ = q->buf[q->pread];
+    q->pread = q->pread + 1 % TTY_BUF_SIZE;
+  }
+
+  return len;
+}
+
+void tty_init(void) {
+  int i;
+
+  for(i = 0; i < NRTTY; i++) {
+    if(!ttys[i])
+      continue;
+
+    memset(&ttys[i]->rqueue, 0, sizeof(struct tty_queue));
+    memset(&ttys[i]->wqueue, 0, sizeof(struct tty_queue));
+
+    ttys[i]->rqueue.pwrite = 1;
+    ttys[i]->wqueue.pwrite = 1;
+
+    if(ttys[i]->init)
+      ttys[i]->init();
+  }
+}