From 2932e2946e8924c8974a4f9adb5937fef0d90056 Mon Sep 17 00:00:00 2001
From: Mattia Giambirtone <hackhab@gmail.com>
Date: Wed, 16 Nov 2022 20:24:23 +0100
Subject: [PATCH] Cleanup and refactoring

---
 .vscode/settings.json                |  5 +++++
 build-cross-compiler.sh              | 19 ++++++++++++++++++
 build.sh                             |  7 ++++---
 env.sh                               |  2 +-
 src/{bootloader => boot}/gdt.s       |  0
 src/{bootloader => boot}/mbr.s       |  8 ++++----
 src/{bootloader => boot}/switch32.s  |  0
 src/{bootloader => boot}/util/disk.s |  0
 src/{bootloader => boot}/util/io.s   |  0
 src/kernel/drivers/vga/video.c       | 30 ++++++++++++++++++++++++++++
 src/kernel/drivers/vga/video.h       | 14 +++++++++++++
 src/kernel/main.c                    | 13 +++++-------
 src/kernel/types/ktypes.h            | 15 ++++++++++++++
 13 files changed, 97 insertions(+), 16 deletions(-)
 create mode 100644 .vscode/settings.json
 create mode 100755 build-cross-compiler.sh
 rename src/{bootloader => boot}/gdt.s (100%)
 rename src/{bootloader => boot}/mbr.s (93%)
 rename src/{bootloader => boot}/switch32.s (100%)
 rename src/{bootloader => boot}/util/disk.s (100%)
 rename src/{bootloader => boot}/util/io.s (100%)
 create mode 100644 src/kernel/drivers/vga/video.c
 create mode 100644 src/kernel/drivers/vga/video.h
 create mode 100644 src/kernel/types/ktypes.h

diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..6f2e1e8
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,5 @@
+{
+    "files.associations": {
+        "ktypes.h": "c"
+    }
+}
\ No newline at end of file
diff --git a/build-cross-compiler.sh b/build-cross-compiler.sh
new file mode 100755
index 0000000..ba28f1a
--- /dev/null
+++ b/build-cross-compiler.sh
@@ -0,0 +1,19 @@
+#!/bin/bash
+mkdir /tmp/src
+cd /tmp/src
+curl -O http://ftp.gnu.org/gnu/binutils/binutils-2.39.tar.gz
+tar xf binutils-2.39.tar.gz
+mkdir binutils-build
+cd binutils-build
+../binutils-2.39/configure --target=$TARGET --enable-interwork --enable-multilib --disable-nls --disable-werror --prefix=$PREFIX 2>&1 | tee configure.log
+sudo make all install 2>&1 | tee make.log
+cd /tmp/src
+curl -O https://ftp.gnu.org/gnu/gcc/gcc-12.2.0/gcc-12.2.0.tar.gz
+tar xf gcc-12.2.0.tar.gz
+mkdir gcc-build
+cd gcc-build
+../gcc-12.2.0/configure --target=$TARGET --prefix="$PREFIX" --disable-nls --disable-libssp --enable-languages=c --without-headers
+sudo make all-gcc 
+sudo make all-target-libgcc 
+sudo make install-gcc 
+sudo make install-target-libgcc 
diff --git a/build.sh b/build.sh
index 127e7fe..4f68749 100755
--- a/build.sh
+++ b/build.sh
@@ -1,5 +1,6 @@
 #!/bin/bash
-i386-elf-gcc -ffreestanding -c src/kernel/main.c -o main.o
-nasm -f elf src/entrypoint.s -o entrypoint.o
-i386-elf-ld -o kernel.bin -Ttext 0x1000 entrypoint.o main.o --oformat binary
+i386-elf-gcc -ffreestanding -c src/kernel/main.c -o kernel.o
+nasm -f elf src/entrypoint.s -o entry.o
+nasm -f bin src/boot/mbr.s -o mbr.bin
+i386-elf-ld -o kernel.bin -Ttext 0x1000 entry.o kernel.o --oformat binary
 cat mbr.bin kernel.bin > os.bin
diff --git a/env.sh b/env.sh
index 54a708f..7fe3332 100755
--- a/env.sh
+++ b/env.sh
@@ -3,4 +3,4 @@ export CC=/usr/bin/gcc
 export LD=/usr/bin/gcc
 export PREFIX="/usr/local/i386elfgcc"
 export TARGET=i386-elf
-export PATH="$PREFIX/bin:$PATH"
+export PATH=$PATH:$PREFIX/bin
diff --git a/src/bootloader/gdt.s b/src/boot/gdt.s
similarity index 100%
rename from src/bootloader/gdt.s
rename to src/boot/gdt.s
diff --git a/src/bootloader/mbr.s b/src/boot/mbr.s
similarity index 93%
rename from src/bootloader/mbr.s
rename to src/boot/mbr.s
index ec5848b..ae51b9d 100644
--- a/src/bootloader/mbr.s
+++ b/src/boot/mbr.s
@@ -25,10 +25,10 @@ jmp $ ; Keeps jumping at the current address (loops forever)
 
 ; Now we include our "function definitions" (after the 
 ; loop, so they're never executed unless explicitly called)
-%include "src/bootloader/util/disk.s"
-%include "src/bootloader/util/io.s"
-%include "src/bootloader/gdt.s"
-%include "src/bootloader/switch32.s"
+%include "src/boot/util/disk.s"
+%include "src/boot/util/io.s"
+%include "src/boot/gdt.s"
+%include "src/boot/switch32.s"
 
 [bits 16]       ; All x86 CPUs start in 16 bit (aka "real") mode, so we tell nasm to emit 16-bit code
 load_kernel:    ; Loads the kernel into memory
diff --git a/src/bootloader/switch32.s b/src/boot/switch32.s
similarity index 100%
rename from src/bootloader/switch32.s
rename to src/boot/switch32.s
diff --git a/src/bootloader/util/disk.s b/src/boot/util/disk.s
similarity index 100%
rename from src/bootloader/util/disk.s
rename to src/boot/util/disk.s
diff --git a/src/bootloader/util/io.s b/src/boot/util/io.s
similarity index 100%
rename from src/bootloader/util/io.s
rename to src/boot/util/io.s
diff --git a/src/kernel/drivers/vga/video.c b/src/kernel/drivers/vga/video.c
new file mode 100644
index 0000000..b68d641
--- /dev/null
+++ b/src/kernel/drivers/vga/video.c
@@ -0,0 +1,30 @@
+// Implementation of a simple video driver using VGA text mode
+#include "video.h"
+
+
+uchar_t vga_readb(u16_t port) {
+    // Reads a byte from the specified I/O port
+    uchar_t result;
+    __asm__("in %%dx, %%al" : "=a" (result) : "d" (port));
+    return result;
+}
+
+
+void vga_writeb(u16_t port, uchar_t data) {
+    // Writes a byte from the specified I/O port
+    __asm__("out %%al, %%dx" : : "a" (data), "d" (port));
+}
+
+
+u16_t vga_writew(u16_t port) {
+    // Reads a word (16 bits) from the specified I/O port
+    u16_t result;
+    __asm__("in %%dx, %%ax" : "=a" (result) : "d" (port));
+    return result;
+}
+
+
+void vga_readw(u16_t port, u16_t data) {
+    // Writes a word (16 bits) to the specified I/O port
+    __asm__("out %%ax, %%dx" : : "a" (data), "d" (port));
+}
\ No newline at end of file
diff --git a/src/kernel/drivers/vga/video.h b/src/kernel/drivers/vga/video.h
new file mode 100644
index 0000000..637c706
--- /dev/null
+++ b/src/kernel/drivers/vga/video.h
@@ -0,0 +1,14 @@
+#ifndef TSOS_DRV_VGA_H  // Avoid nasty double-inclusion problems
+#define TSOS_DRV_VGA_H
+#define VMEM_ADDR 0xb8000
+#include "kernel/types/ktypes.h"
+
+
+uchar_t vga_writeb(u16_t port);
+void vga_readb(u16_t port, uchar_t data);
+u16_t vga_writew(u16_t port);
+void vga_readw(u16_t port, u16_t data);
+
+
+
+#endif
\ No newline at end of file
diff --git a/src/kernel/main.c b/src/kernel/main.c
index 76e3163..79fc590 100644
--- a/src/kernel/main.c
+++ b/src/kernel/main.c
@@ -1,15 +1,12 @@
-// C entry point of our kernel
-#define VMEM_ADDR 0xb8000
-
-void dummy_test_entrypoint(void) {
-}
+// Entry point of the TSOS kernel
+#include "types/ktypes.h"
 
 
 void kmain(void) {
-    char* vbuf = (char*)VMEM_ADDR;
+    char_t* vbuf = (char_t*)0xb8000;
     vbuf += 480;    // We skip the log messages before us
-    char *s = "Hello from the TSOS kernel!";
-    for (int i = 0; s[i] != '\0'; i++) {
+    char_t *s = "Hello from the TSOS kernel!";
+    for (int_t i = 0; s[i] != '\0'; i++) {
         *vbuf = s[i];
         vbuf += 2;
     }
diff --git a/src/kernel/types/ktypes.h b/src/kernel/types/ktypes.h
new file mode 100644
index 0000000..462a8d0
--- /dev/null
+++ b/src/kernel/types/ktypes.h
@@ -0,0 +1,15 @@
+// Shorthand definitions of various types
+// used in the kernel
+#ifndef TSOS_KTYPES
+#define TSOS_KTYPES
+
+
+typedef unsigned char uchar_t;
+typedef unsigned short int u16_t;
+typedef short int i16_t;
+typedef char char_t;
+typedef unsigned int uint_t;
+typedef int int_t;
+
+
+#endif
\ No newline at end of file