From 9b22a6965579ea1867aea291d910c96f386b518b Mon Sep 17 00:00:00 2001
From: Brett Weiland <brett_weiland@bpcspace.com>
Date: Tue, 24 Aug 2021 14:09:29 -0500
Subject: major backup 8.24.21

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

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

diff --git a/src/kernel/klog.c b/src/kernel/klog.c
new file mode 100644
index 0000000..52444b1
--- /dev/null
+++ b/src/kernel/klog.c
@@ -0,0 +1,100 @@
+#include <stdint.h>
+#include <serial.h>
+#include <io.h>
+#include <printf.h>
+#include <kernel.h>
+#include <stdbool.h>
+#include <libc.h>
+
+//README 
+//this file has some temporary workarounds until I get further into development
+//this isn't going to be the serial driver I end up keeping
+
+#define VIDEO_BUFFER PHYS_TO_VIRT(0xb8000)
+#define MAX_LOOPBACK_ATTEMPTS 20
+
+//later we'll set it up for interrupting instead of polling
+bool init_serial(uint16_t port) {
+  outb_wait(port + 1, 0x00); 
+  outb_wait(port + 2, 0x00); 
+  outb_wait(port + 3, 0x80); 
+  outb_wait(port + 0, 0x01); //here
+  outb_wait(port + 1, 0x00);
+  outb_wait(port + 3, 0x03); 
+  outb_wait(port + 2, 0xc7); 
+  outb_wait(port + 4, 0x0b); 
+  outb_wait(port + 4, 0x1e); 
+
+
+  //we shouldn't accept this as a loopback success.
+  //I'm making an exception because my dell desktop has a faulty serial port
+  //that requires some extra effort.
+
+  uint8_t loopback_byte;
+  for(int attempts = 0; attempts < MAX_LOOPBACK_ATTEMPTS; attempts++) {
+    outb_wait(port + 0, 0xae); // test char
+    loopback_byte = inb(port);
+    if(loopback_byte == 0xae) break;
+  }
+
+  if(loopback_byte != 0xae) {
+    //I'm sorry if these next few lines give you a stroke. They gave me one.
+    
+    //My old Dell test desktop has disfunctional serial hardware that only works after a reboot.
+    //Seeing we don't have ACPI set up yet, we can't reboot without crashing.
+    //IM GOING TO REMOVE THIS ONCE I DEVELOP THE "REAL" SERIAL DRIVER!!!! 
+    asm("mov rax, 0\n"
+        "div rax\n");
+    return false;
+  }
+  
+  outb_wait(port + 4, 0x0f); 
+  return true;
+}
+
+void _putchar_serial(uint16_t port, char msg) {
+  while(!(inb(port + 5) & 0x20)); //wait for transmit to be done
+  outb_wait(port, msg);
+}
+
+static unsigned int on_char = 0;
+static unsigned int on_line = 0;
+
+
+void clear_screen() {
+  char *screen_buffer = (void *)VIDEO_BUFFER;
+  for(unsigned int i = 0; i <= (80 * 25); i++) screen_buffer[i * 2] = ' ';
+  on_char = 0;
+  on_line = 0;
+} 
+
+void next_line() {
+  if(on_line >= 25) {
+    on_line = 0;
+    clear_screen();
+  }
+  else {
+    on_line++;
+  }
+  on_char = 0;
+}
+
+void move_cursor(unsigned int x, unsigned int y) {
+  //yeah yeah yeah, it doens't test for overflows... I'm gonna delete this once i get serial working
+  //on my second desktop
+  on_char = x;
+  on_line = y;
+}
+
+//until we get serial working on hp
+void _putchar_screen(char msg) {
+  if(on_char >= 80) {
+    next_line();
+  } else if(msg == '\n') {
+    next_line();
+    return;
+  }
+  char *screen_buffer = (void *)((uint64_t)VIDEO_BUFFER + ((on_line * 160) + (on_char * 2)));
+  *screen_buffer = msg;
+  on_char++;
+}
-- 
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