From 37cb11cec0735aa98052dab252a0cdb958c115d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nicol=C3=A1s=20Ortega=20Froysa?=
 <nortega@themusicinnoise.net>
Date: Sat, 24 Feb 2018 10:00:00 +0100
Subject: [PATCH] Add ports files and add use ANSI C.

---
 Makefile       |  6 +++---
 kernel/ports.c | 23 +++++++++++++++++++++++
 kernel/ports.h | 18 ++++++++++++++++++
 3 files changed, 44 insertions(+), 3 deletions(-)
 create mode 100644 kernel/ports.c
 create mode 100644 kernel/ports.h

diff --git a/Makefile b/Makefile
index 3e52a10..26ff8db 100644
--- a/Makefile
+++ b/Makefile
@@ -1,11 +1,11 @@
 ASM=nasm
 BIN=bin
-CFLAGS=-ffreestanding -fno-pie -m32
+CFLAGS=-ffreestanding -fno-pie -m32 -ansi
 CC=gcc
 LD=ld
 LDFLAGS=-melf_i386 -Ttext 0x1000 --oformat binary
 
-OBJ=kernel/kernel_entry.o kernel/kernel.o
+OBJ=kernel/kernel_entry.o kernel/kernel.o kernel/ports.o
 
 all: os-image
 
@@ -29,5 +29,5 @@ kernel/kernel.bin: $(OBJ)
 .PHONY: clean
 
 clean:
-	rm -rf boot/*.bin boot/*.o
+	rm -rf boot/*.bin kernel/*.bin
 	rm -rf kernel/*.o boot/*.o drivers/*.o
diff --git a/kernel/ports.c b/kernel/ports.c
new file mode 100644
index 0000000..a795775
--- /dev/null
+++ b/kernel/ports.c
@@ -0,0 +1,23 @@
+unsigned char port_byte_in(unsigned char port) {
+	unsigned char res;
+	/*
+	 * `"=a" (res)' means: put result of `al' into `res' variable
+	 * `"d" (port)' means: load `port' into `dx'.
+	 */
+	__asm__("in %%dx, %%al" : "=a" (res) : "d" (port));
+	return res;
+}
+
+void port_byte_out(unsigned char port, unsigned char data) {
+	__asm__("out %%al, %%dx" : : "a" (data), "d" (port));
+}
+
+unsigned short port_word_in(unsigned short port) {
+	unsigned short res;
+	__asm__("in %%dx, %%ax" : "=a" (res) : "d" (port));
+	return res;
+}
+
+void port_word_out(unsigned short port, unsigned short data) {
+	__asm__("out %%ax, %%dx" : : "a" (data), "d" (port));
+}
diff --git a/kernel/ports.h b/kernel/ports.h
new file mode 100644
index 0000000..ab47a3b
--- /dev/null
+++ b/kernel/ports.h
@@ -0,0 +1,18 @@
+#pragma once
+
+/*
+ * return a byte from a port.
+ */
+unsigned char port_byte_in(unsigned char port);
+/*
+ * write a byte of data to a port.
+ */
+void port_byte_out(unsigned char port, unsigned char data);
+/*
+ * return a word of data from a port.
+ */
+unsigned short port_word_in(unsigned short port);
+/*
+ * write a word of data to a port.
+ */
+void port_word_out(unsigned short port, unsigned short data);