1 files changed, 74 insertions, 0 deletions
diff --git a/common/console.c b/common/console.c
new file mode 100644
index 0000000..a7108ba
--- /dev/null
+++ b/common/console.c
@@ -0,0 +1,74 @@
+/*
+ * console.c - the console dprintf writes to. semihosting SYS_WRITE0,
+ * the firmware service on the qemu dev path, the arm64 stand-in for
+ * the bios teletype the osdev loaders use. on real hardware this is
+ * the one file that changes.
+ *
+ * Copyright (c) 2026 Bradley Morgan <brads@mainlining.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <debug.h>
+#include <semihosting.h>
+
+/*
+ * lk's _dprintf sink. printf buffers a line here then hands it to the
+ * host, semihosting wants zero terminated strings not counts.
+ */
+#define TB_CONSOLE_MAX	256
+
+static char console_buf[TB_CONSOLE_MAX];
+static size_t console_len;
+
+static void console_flush(void)
+{
+	if (console_len == 0)
+		return;
+	console_buf[console_len] = '\0';
+	smh_write0(console_buf);
+	console_len = 0;
+}
+
+void _putchar(char c)
+{
+	if (console_len >= TB_CONSOLE_MAX - 1)
+		console_flush();
+	if (c == '\n') {
+		/* the host terminal wants cr lf, not lf alone */
+		console_buf[console_len++] = '\r';
+	}
+	console_buf[console_len++] = c;
+	if (c == '\n')
+		console_flush();
+}
+
+int tb_console_init(void)
+{
+	/*
+	 * the probe is one harmless call: SYS_GET_ERRNO with no file
+	 * handle open. a host answers, bare metal ignores the trap.
+	 */
+	if (!smh_probe())
+		return -1;
+	console_len = 0;
+	return 0;
+}