From 791679dcd0a2bd8880c81bdd3fe3ffa8c0527de5 Mon Sep 17 00:00:00 2001
From: g1n <g1n@ttm.sh>
Date: Wed, 11 Aug 2021 14:05:06 +0300
Subject: [PATCH] Kernel: add asm_helper.h - some asm constructions (outb, inb)

---
 kernel/kernel/asm_helper.h | 17 +++++++++++++++++
 kernel/kernel/serial.h     | 20 ++------------------
 2 files changed, 19 insertions(+), 18 deletions(-)
 create mode 100644 kernel/kernel/asm_helper.h

diff --git a/kernel/kernel/asm_helper.h b/kernel/kernel/asm_helper.h
new file mode 100644
index 0000000..60c8a1d
--- /dev/null
+++ b/kernel/kernel/asm_helper.h
@@ -0,0 +1,17 @@
+inline void outb(uint16_t port, uint8_t val)
+{
+    asm volatile ( "outb %0, %1" : : "a"(val), "Nd"(port) );
+    /* There's an outb %al, $imm8  encoding, for compile-time constant port numbers that fit in 8b.  (N constraint).
+     * Wider immediate constants would be truncated at assemble-time (e.g. "i" constraint).
+     * The  outb  %al, %dx  encoding is the only option for all other cases.
+     * %1 expands to %dx because  port  is a uint16_t.  %w1 could be used if we had the port number a wider C type */
+}
+
+inline int inb(int port)
+{
+    uint8_t ret;
+    asm volatile ( "inb %1, %0"
+                   : "=a"(ret)
+                   : "Nd"(port) );
+    return ret;
+}
diff --git a/kernel/kernel/serial.h b/kernel/kernel/serial.h
index 94eb14d..abb11ca 100644
--- a/kernel/kernel/serial.h
+++ b/kernel/kernel/serial.h
@@ -4,6 +4,8 @@
 #include <limits.h>
 #include <stdbool.h>
 
+#include "asm_helper.h"
+
 #define PORT 0x3f8          // COM1
  
 static int init_serial() {
@@ -127,21 +129,3 @@ int serial_printf(const char* restrict format, ...) {
 	va_end(parameters);
 	return written;
 }
-
-inline void outb(uint16_t port, uint8_t val)
-{
-    asm volatile ( "outb %0, %1" : : "a"(val), "Nd"(port) );
-    /* There's an outb %al, $imm8  encoding, for compile-time constant port numbers that fit in 8b.  (N constraint).
-     * Wider immediate constants would be truncated at assemble-time (e.g. "i" constraint).
-     * The  outb  %al, %dx  encoding is the only option for all other cases.
-     * %1 expands to %dx because  port  is a uint16_t.  %w1 could be used if we had the port number a wider C type */
-}
-
-inline int inb(int port)
-{
-    uint8_t ret;
-    asm volatile ( "inb %1, %0"
-                   : "=a"(ret)
-                   : "Nd"(port) );
-    return ret;
-}