arch: i386: add support for x86 processors

Add support for 32-bit x86 processors, i.e. the 80386 and above.

Signed-off-by: Danny Holman <dholman@gymli.xyz>

1 files changed, 55 insertions, 0 deletions

diff --git a/arch/i386/tty.c b/arch/i386/tty.c
new file mode 100644
index 0000000..9c3985b
--- /dev/null
+++ b/arch/i386/tty.c
@@ -0,0 +1,55 @@
+#include "vga.h"
+#include <kernel/tty.h>
+#include <kernel/string.h>
+#include <stddef.h>
+#include <stdint.h>
+
+static const size_t VGA_WIDTH = 80;
+static const size_t VGA_HEIGHT = 25;
+static uint16_t *const VGA_MEMORY = (uint16_t*)0xB8000;
+
+static size_t terminal_row;
+static size_t terminal_column;
+static uint8_t terminal_color;
+static uint16_t *terminal_buffer;
+
+void tty_init(void) {
+        terminal_row = 0;
+        terminal_column = 0;
+        terminal_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
+        terminal_buffer = VGA_MEMORY;
+        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] = vga_entry(' ', terminal_color);
+                }
+        }
+}
+
+void tty_setcolor(uint8_t color) {
+        terminal_color = color;
+}
+
+void tty_putentryat(unsigned char c, uint8_t color, size_t x, size_t y) {
+        const size_t index = y * VGA_WIDTH + x;
+        terminal_buffer[index] = vga_entry(c, color);
+}
+
+void tty_putchar(char c) {
+        unsigned char uc = c;
+        tty_putentryat(uc, terminal_color, terminal_column, terminal_row);
+        if (++terminal_column == VGA_WIDTH) {
+                terminal_column = 0;
+                if (++terminal_row == VGA_HEIGHT)
+                        terminal_row = 0;
+        }
+}
+
+void tty_write(const char *data, size_t size) {
+        for (size_t i = 0; i < size; i++)
+                tty_putchar(data[i]);
+}
+
+void tty_writestring(const char *data) {
+        tty_write(data, strlen(data));
+}