Initial commit

1 files changed, 87 insertions, 0 deletions

diff --git a/src/stdio.c b/src/stdio.c
new file mode 100644
index 0000000..6aee7b3
--- /dev/null
+++ b/src/stdio.c
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2017 Richard Braun.
+ *
+ * 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 <stdarg.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#include "cpu.h"
+#include "thread.h"
+#include "uart.h"
+
+#define PRINTF_BUFFER_SIZE 1024
+
+/*
+ * This implementation uses a global buffer in order to avoid allocating
+ * from the stack, since stacks may be very small.
+ */
+static char printf_buffer[PRINTF_BUFFER_SIZE];
+
+void
+putchar(unsigned char c)
+{
+    uart_write(c);
+}
+
+int
+getchar(void)
+{
+    uint8_t byte;
+    int error;
+
+    error = uart_read(&byte);
+    return error ? EOF : byte;
+}
+
+int
+printf(const char *format, ...)
+{
+    va_list ap;
+    int length;
+
+    va_start(ap, format);
+    length = vprintf(format, ap);
+    va_end(ap);
+
+    return length;
+}
+
+int
+vprintf(const char *format, va_list ap)
+{
+    uint32_t eflags;
+    int length;
+
+    thread_preempt_disable();
+    eflags = cpu_intr_save();
+
+    length = vsnprintf(printf_buffer, sizeof(printf_buffer), format, ap);
+
+    for (const char *ptr = printf_buffer; *ptr != '\0'; ptr++) {
+        uart_write((uint8_t)*ptr);
+    }
+
+    cpu_intr_restore(eflags);
+    thread_preempt_enable();
+
+    return length;
+}