From 571a656a6bd9b4b9d5c595c578d15ba79bb19ef7 Mon Sep 17 00:00:00 2001
From: Samuel Johnson <sjohnson1149@proton.me>
Date: Tue, 1 Jul 2025 10:33:05 -0400
Subject: Add serial logging

---
 kernel/amd64/io/com1.cxx | 44 ++++++++++++++++++++++++++++++++++++++++++++
 kernel/amd64/io/com1.h   | 17 +++++++++++++++++
 kernel/amd64/io/ports.S  | 24 ++++++++++++++++++++++++
 kernel/amd64/io/ports.h  | 12 ++++++++++++
 4 files changed, 97 insertions(+)
 create mode 100644 kernel/amd64/io/com1.cxx
 create mode 100644 kernel/amd64/io/com1.h
 create mode 100644 kernel/amd64/io/ports.S
 create mode 100644 kernel/amd64/io/ports.h

(limited to 'kernel/amd64/io')

diff --git a/kernel/amd64/io/com1.cxx b/kernel/amd64/io/com1.cxx
new file mode 100644
index 0000000..fc67b65
--- /dev/null
+++ b/kernel/amd64/io/com1.cxx
@@ -0,0 +1,44 @@
+#include <amd64/io/com1.h>
+#include <amd64/io/ports.h>
+#include <utils.h>
+
+#define COM1 0x3f8
+
+int is_transmit_empty ()
+{
+    return hos::io::inb(COM1 + 5) & 0x20;
+}
+
+namespace hos::io
+{
+    com_logger::com_logger (enum log_level level)
+        : logger (level)
+    {
+        outb(COM1 + 1, 0x00);
+        outb(COM1 + 3, 0x80);
+        outb(COM1 + 0, 0x03);
+        outb(COM1 + 1, 0x00);
+        outb(COM1 + 3, 0x03);
+        outb(COM1 + 2, 0xc7);
+        outb(COM1 + 4, 0x0b);
+        outb(COM1 + 4, 0x1e);
+        outb(COM1 + 0, 0xae);
+
+        if (inb(COM1 + 0) != 0xae)
+        {
+            return;
+        }
+
+        outb(COM1 + 4, 0x0f);
+    }
+
+    void com_logger::flush ()
+    {
+        std::size_t len = strlen(this->buffer);
+        for (std::size_t i = 0; i < len; i++)
+        {
+            while (is_transmit_empty() == 0);
+            outb(COM1 + 0, this->buffer[i]);
+        }
+    }
+}
diff --git a/kernel/amd64/io/com1.h b/kernel/amd64/io/com1.h
new file mode 100644
index 0000000..0ee04ac
--- /dev/null
+++ b/kernel/amd64/io/com1.h
@@ -0,0 +1,17 @@
+#ifndef HOS_AMD64_IO_COM1_H
+#define HOS_AMD64_IO_COM1_H
+
+#include <amd64/io/ports.h>
+#include <io/logger/base.h>
+
+namespace hos::io
+{
+    class com_logger : public hos::io::logger<com_logger>
+    {
+    public:
+        com_logger      (enum log_level level);
+        void    flush   ();
+    };
+}
+
+#endif
diff --git a/kernel/amd64/io/ports.S b/kernel/amd64/io/ports.S
new file mode 100644
index 0000000..37301a4
--- /dev/null
+++ b/kernel/amd64/io/ports.S
@@ -0,0 +1,24 @@
+.section .text
+.global inb, outb
+
+inb:
+    push    %rbp
+    mov     %rsp, %rbp
+    sub     $0x10, %rsp
+    mov     %rdi, %rdx
+    xor     %rax, %rax
+    in      (%dx), %al
+    add     $0x10, %rsp
+    pop     %rbp
+    ret
+
+outb:
+    push    %rbp
+    mov     %rsp, %rbp
+    sub     $0x10, %rsp
+    mov     %rdi, %rdx
+    mov     %rsi, %rax
+    out     %al, (%dx)
+    add     $0x10, %rsp
+    pop     %rbp
+    ret
diff --git a/kernel/amd64/io/ports.h b/kernel/amd64/io/ports.h
new file mode 100644
index 0000000..6de2acb
--- /dev/null
+++ b/kernel/amd64/io/ports.h
@@ -0,0 +1,12 @@
+#ifndef HOS_AMD64_IO_PORTS_H
+#define HOS_AMD64_IO_PORTS_H
+
+#include <cstdint>
+
+namespace hos::io
+{
+    extern "C" std::uint8_t inb     (std::uint16_t port);
+    extern "C" void         outb    (std::uint16_t port, std::uint8_t value);
+}
+
+#endif
-- 
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