add tty.c tty.h for terminal handling

5 files changed, 119 insertions, 105 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 9846422..6c1b3ae 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -3,8 +3,8 @@ all: kernel.elf
 .c.o :
 	gcc -std=gnu99 -m32 -fno-builtin -ffreestanding -nostdlib -Wall -Wextra -c $< -o $@
 
-kernel.elf: kernel.o entry.o
-	ld -Tlinker.ld -melf_i386 entry.o kernel.o -o kernel.elf
+kernel.elf: kernel.o tty.o tty.h entry.o
+	ld -Tlinker.ld -melf_i386 entry.o tty.o kernel.o -o kernel.elf
 
 # entry.o: entry.S
 # 	as -32 $< -o entry.o
diff --git a/kernel/kernel.c b/kernel/kernel.c
index 5054231..d65b07d 100644
--- a/kernel/kernel.c
+++ b/kernel/kernel.c
@@ -1,114 +1,15 @@
-#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__)
-/* TODO how does this check for a cross compiler? It was failing. */
-/*#error "You are not using a cross-compiler, you will most certainly run into trouble"*/
-#endif
+#include "tty.h"
 
-/* This tutorial will only work for the 32-bit ix86 targets. */
+/* this 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,
-};
-
-static uint8_t make_color(enum vga_color fg, enum vga_color bg)
-{
-    return fg | bg << 4;
-}
-
-static uint16_t make_vgaentry(char c, uint8_t color)
-{
-    uint16_t c16 = c;
-    uint16_t color16 = color;
-    return c16 | color16 << 8;
-}
-
-/* static size_t strlen(const char* str) */
-/* { */
-/*     size_t ret = 0; */
-/*     for (const char* p = str; *p != 0; p++, 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;
-
-static 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);
-        }
-    }
-}
-
-/* static void terminal_setcolor(uint8_t color) */
-/* { */
-/*     terminal_color = color; */
-/* } */
-
-static 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);
-}
-
-static 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;
-        }
-    }
-}
-
-static void terminal_writestring(const char* data)
-{
-    for (const char* p = data; *p != 0; p++)
-        terminal_putchar(*p);
-}
-
 #if defined(__cplusplus)
 extern "C" /* Use C linkage for kernel_main. */
 #endif
 void kernel_main()
 {
-    terminal_initialize();
-    terminal_writestring("Hello, kernel World!\n");
+    tty_init();
+    tty_writestring("Hello, kernel World!\n");
 }
diff --git a/kernel/tty.c b/kernel/tty.c
new file mode 100644
index 0000000..4cb2cf1
--- /dev/null
+++ b/kernel/tty.c
@@ -0,0 +1,83 @@
+#include "tty.h"
+
+/* 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,
+};
+
+#define VGA_WIDTH   80
+#define VGA_HEIGHT  25
+#define VGA_TEXT_BUFFER 0xB8000
+#define VGA_COLOR_SHIFT 8
+
+static size_t tty_row;
+static size_t tty_col;
+static uint8_t tty_color;
+static uint16_t* tty_buffer;
+
+static inline uint8_t make_color(enum vga_color fg, enum vga_color bg)
+{
+    return fg | bg << 4;
+}
+
+static inline uint16_t make_vgaentry(char c, uint8_t color)
+{
+    return ((uint16_t) c) | (((uint16_t) color) << VGA_COLOR_SHIFT);
+}
+
+static inline void tty_putentryat(char c, uint8_t color, size_t x, size_t y)
+{
+    const size_t i = y * VGA_WIDTH + x;
+    tty_buffer[i] = make_vgaentry(c, color);
+}
+
+void tty_setcolor(uint8_t color)
+{
+    tty_color = color;
+}
+
+void tty_putchar(char c)
+{
+    tty_putentryat(c, tty_color, tty_col, tty_row);
+    if (++tty_col == VGA_WIDTH) {
+        tty_col = 0;
+        if (++tty_row == VGA_HEIGHT) {
+            tty_row = 0;
+        }
+    }
+}
+
+void tty_writestring(const char* data)
+{
+    for (const char* p = data; *p != 0; p++)
+        tty_putchar(*p);
+}
+
+void tty_init()
+{
+    tty_row = 0;
+    tty_col = 0;
+    tty_buffer = (uint16_t*) VGA_TEXT_BUFFER;
+    tty_setcolor(make_color(COLOR_LIGHT_GREY, COLOR_BLACK));
+    for (size_t y = 0; y < VGA_HEIGHT; y++) {
+        for (size_t x = 0; x < VGA_WIDTH; x++) {
+            const size_t i = y * VGA_WIDTH + x;
+            tty_buffer[i] = make_vgaentry(' ', tty_color);
+        }
+    }
+}
diff --git a/kernel/tty.h b/kernel/tty.h
new file mode 100644
index 0000000..3c4b09e
--- /dev/null
+++ b/kernel/tty.h
@@ -0,0 +1,14 @@
+#ifndef _TTY_H_
+#define _TTY_H_
+
+#include "types.h"
+
+void tty_init();
+
+void tty_setcolor(uint8_t color);
+
+void tty_putchar(char c);
+
+void tty_writestring(const char* data);
+
+#endif
diff --git a/kernel/types.h b/kernel/types.h
new file mode 100644
index 0000000..5065af7
--- /dev/null
+++ b/kernel/types.h
@@ -0,0 +1,16 @@
+#ifndef _TYPES_H_
+#define _TYPES_H_
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+
+typedef unsigned char uchar;
+typedef unsigned short ushort;
+typedef unsigned int uint;
+typedef unsigned long ulong;
+
+/* #define NULL 0 */
+
+#endif
+