From 6eabea2067647f094005a7497eca2cef32900147 Mon Sep 17 00:00:00 2001
From: ty2-yuen <tsz2.yuen@live.uwe.ac.uk>
Date: Fri, 6 Nov 2020 15:47:00 +0000
Subject: [PATCH] Revert "Delete kernel.c"
This reverts commit 2dc94f5862cfc9bae087ea04dfac56bcf0d0a02f
---
minimalOS/kernel.c | 115 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 115 insertions(+)
create mode 100644 minimalOS/kernel.c
diff --git a/minimalOS/kernel.c b/minimalOS/kernel.c
new file mode 100644
index 0000000..e41db16
--- /dev/null
+++ b/minimalOS/kernel.c
@@ -0,0 +1,115 @@
+/*
+ * Desc: Minimal OS, to show how to boot an x86 machine. UFCFWK-15-2
+ */
+#if !defined(__cplusplus)
+#include <stdbool.h> /* C doesn't have booleans by default. */
+#endif
+#include <stddef.h>
+#include <stdint.h>
+
+/* Check if the compiler thinks we are targeting the wrong operating system. */
+#if defined(__linux__)
+#error "You are not using a cross-compiler, you will most certainly run into trouble"
+#endif
+
+/* This tutorial will only work for the 32-bit ix86 targets. */
+#if !defined(__i386__)
+#error "This tutorial needs to be compiled with a ix86-elf compiler"
+#endif
+
+/* Hardware text mode color constants. */
+enum vga_color {
+ COLOR_BLACK = 0,
+ COLOR_BLUE = 1,
+ COLOR_GREEN = 2,
+ COLOR_CYAN = 3,
+ COLOR_RED = 4,
+ COLOR_MAGENTA = 5,
+ COLOR_BROWN = 6,
+ COLOR_LIGHT_GREY = 7,
+ COLOR_DARK_GREY = 8,
+ COLOR_LIGHT_BLUE = 9,
+ COLOR_LIGHT_GREEN = 10,
+ COLOR_LIGHT_CYAN = 11,
+ COLOR_LIGHT_RED = 12,
+ COLOR_LIGHT_MAGENTA = 13,
+ COLOR_LIGHT_BROWN = 14,
+ COLOR_WHITE = 15,
+};
+
+uint8_t make_color(enum vga_color fg, enum vga_color bg) {
+ return fg | bg << 4;
+}
+
+uint16_t make_vgaentry(char c, uint8_t color) {
+ uint16_t c16 = c;
+ uint16_t color16 = color;
+ return c16 | color16 << 8;
+}
+
+size_t strlen(const char* str) {
+ size_t ret = 0;
+ while ( str[ret] != 0 )
+ ret++;
+ return ret;
+}
+
+static const size_t VGA_WIDTH = 80;
+static const size_t VGA_HEIGHT = 25;
+
+size_t terminal_row;
+size_t terminal_column;
+uint8_t terminal_color;
+uint16_t* terminal_buffer;
+
+void terminal_initialize() {
+ terminal_row = 0;
+ terminal_column = 0;
+ terminal_color = make_color(COLOR_LIGHT_GREY, COLOR_BLACK);
+ terminal_buffer = (uint16_t*) 0xB8000;
+ for (size_t y = 0; y < VGA_HEIGHT; y++) {
+ for (size_t x = 0; x < VGA_WIDTH; x++) {
+ const size_t index = y * VGA_WIDTH + x;
+ terminal_buffer[index] = make_vgaentry(' ', terminal_color);
+ }
+ }
+}
+
+void terminal_setcolor(uint8_t color) {
+ terminal_color = color;
+}
+
+void terminal_putentryat(char c, uint8_t color, size_t x, size_t y) {
+ const size_t index = y * VGA_WIDTH + x;
+ terminal_buffer[index] = make_vgaentry(c, color);
+}
+
+void terminal_putchar(char c) {
+ terminal_putentryat(c, terminal_color, terminal_column, terminal_row);
+ if (++terminal_column == VGA_WIDTH) {
+ terminal_column = 0;
+ if (++terminal_row == VGA_HEIGHT) {
+ terminal_row = 0;
+ }
+ }
+}
+
+void terminal_writestring(const char* data) {
+ size_t datalen = strlen(data);
+ for (size_t i = 0; i < datalen; i++)
+ terminal_putchar(data[i]);
+}
+
+#if defined(__cplusplus)
+extern "C" /* Use C linkage for kernel_main. */
+#endif
+void kernel_main() {
+ /* Initialize terminal interface */
+ terminal_initialize();
+
+ /* Since there is no support for newlines in terminal_putchar
+ * yet, '\n' will produce some VGA specific character instead.
+ * This is normal.
+ */
+ terminal_writestring("Hello, kernel World!\n");
+}
--
GitLab