Initial commit: SUB-OS 64-Bit Production Monolithic Operating System with LazyBox userland suite

drivers/char/serial.c

@@ -0,0 +1,39 @@
+#include <drivers/serial.h>
+#include <arch/x86_64/io.h>
+
+void serial_init(void) {
+    outb(COM1_PORT + 1, 0x00); // Disable all interrupts
+    outb(COM1_PORT + 3, 0x80); // Enable DLAB (set baud rate divisor)
+    outb(COM1_PORT + 0, 0x03); // Set divisor to 3 (lo byte) 38400 baud
+    outb(COM1_PORT + 1, 0x00); //                  (hi byte)
+    outb(COM1_PORT + 3, 0x03); // 8 bits, no parity, one stop bit
+    outb(COM1_PORT + 2, 0xC7); // Enable FIFO, clear them, with 14-byte threshold
+    outb(COM1_PORT + 4, 0x0B); // IRQs enabled, RTS/DSR set
+}
+
+static bool serial_is_transmit_empty(void) {
+    return (inb(COM1_PORT + 5) & 0x20) != 0;
+}
+
+void serial_write_char(char c) {
+    while (!serial_is_transmit_empty());
+    outb(COM1_PORT, c);
+}
+
+void serial_write_string(const char* str) {
+    while (*str) {
+        if (*str == '\n') {
+            serial_write_char('\r');
+        }
+        serial_write_char(*str++);
+    }
+}
+
+bool serial_received(void) {
+    return (inb(COM1_PORT + 5) & 1) != 0;
+}
+
+char serial_read_char(void) {
+    while (!serial_received());
+    return inb(COM1_PORT);
+}