From 02f14113cbf14c6f842fb43ecbc68d0c851ef3b0 Mon Sep 17 00:00:00 2001
From: Benji Dial <benji3.141@gmail.com>
Date: Sun, 24 May 2020 11:02:43 -0400
Subject: very basic vga, ata, serial drivers. start of fat and fs drivers

---
 src/kernel/serial.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 src/kernel/serial.c

(limited to 'src/kernel/serial.c')

diff --git a/src/kernel/serial.c b/src/kernel/serial.c
new file mode 100644
index 0000000..b88c7ec
--- /dev/null
+++ b/src/kernel/serial.c
@@ -0,0 +1,100 @@
+#include <stdint.h>
+#include <stdbool.h>
+#include "util.h"
+
+enum {
+  CP_DATA    = 0x0,
+  CP_INT     = 0x1,
+  CP_FIFO    = 0x2,
+  CP_LINE    = 0x3,
+  CP_MODEM   = 0x4,
+  CP_LINE_S  = 0x5,
+  CP_MODEM_S = 0x6,
+
+  CP_DIVLOW  = 0x0,
+  CP_DIVHIGH = 0x1,
+
+  CP_1 = 0x03f8,
+  CP_2 = 0x02f8,
+  CP_3 = 0x03e8,
+  CP_4 = 0x02e8
+};
+
+enum {
+  CL_BAUD  = 0x80,
+
+  CL_PODD  = 0x08,
+  CL_PEVEN = 0x0c,
+  CL_PON   = 0x18,
+  CL_POFF  = 0x1c,
+
+  CL_LSTOP = 0x4,
+
+  CL_5BIT  = 0x0,
+  CL_6BIT  = 0x1,
+  CL_7BIT  = 0x2,
+  CL_8BIT  = 0x3
+};
+
+enum {
+  CLS_B_ERR = 0x80,
+  CLS_IDLE  = 0x40,
+  CLS_WRITE = 0x20,
+  CLS_BREAK = 0x10,
+  CLS_FRAME = 0x08,
+  CLS_PAR   = 0x04,
+  CLS_OVER  = 0x02,
+  CLS_READ  = 0x01
+};
+
+bool error;
+#define SERIAL_SPIN_LIMIT 65535
+
+bool serr() {
+  return error;
+}
+
+void sinit() {
+  error = false;
+  outb(CP_1 | CP_INT, 0);
+  outb(CP_1 | CP_LINE, CL_BAUD);
+  outb(CP_1 | CP_DIVLOW, 0x03);//38400
+  outb(CP_1 | CP_DIVHIGH, 0x00);//baud
+  outb(CP_1 | CP_LINE, CL_8BIT);
+  outb(CP_1 | CP_FIFO, 0xc7);//?
+}
+
+void sout(uint8_t b) {
+  if (error)
+    return;
+  uint16_t s = SERIAL_SPIN_LIMIT;
+  while (!(inb(CP_1 | CP_LINE_S) & CLS_WRITE))
+    if (!--s) {
+      error = true;
+      return;
+    }
+  outb(CP_1 | CP_DATA, b);
+}
+
+void soutsz(uint8_t *s) {
+  while (*s)
+    sout(*(s++));
+}
+
+void soutsn(uint8_t *s, uint8_t n) {
+  while (n--)
+    sout(*(s++));
+}
+
+uint8_t sin() {
+  if (error)
+    return 0;
+  while (!(inb(CP_1 | CP_LINE_S) & CLS_READ))
+    ;//spin
+  return inb(CP_1 | CP_DATA);
+}
+
+void sinsn(uint8_t *s, uint8_t n) {
+  while (n--)
+    *(s++) = sin();
+}
\ No newline at end of file
-- 
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