From 832aa58bb7fc2b942a31278fdabe6eab527989d8 Mon Sep 17 00:00:00 2001
From: Gitea <gitea@fake.local>
Date: Tue, 1 Dec 2020 21:00:28 -0600
Subject: [PATCH] Working TTY

---
 arch/i386/tty.c      | 82 ++++++++++++++++++++++++++++++++++++++++++++
 arch/i386/vga.h      | 33 ++++++++++++++++++
 include/kernel/tty.h | 12 +++++++
 3 files changed, 127 insertions(+)
 create mode 100755 arch/i386/tty.c
 create mode 100755 arch/i386/vga.h
 create mode 100755 include/kernel/tty.h

diff --git a/arch/i386/tty.c b/arch/i386/tty.c
new file mode 100755
index 0000000..4c342f3
--- /dev/null
+++ b/arch/i386/tty.c
@@ -0,0 +1,82 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <kernel/tty.h>
+
+#include "vga.h"
+
+static const size_t VGA_WIDTH = 80;
+static const size_t VGA_HEIGHT = 24;
+static uint16_t* const VGA_MEMORY = (uint16_t*) 0xB8000 ;
+
+static size_t term_row;
+static size_t term_col;
+static uint8_t term_color;
+static uint16_t* term_buf;
+
+void term_init(void) {
+  term_row = 0;
+  term_col = 0;
+  term_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
+  term_buf = VGA_MEMORY;
+  for(size_t y = 0; y < VGA_HEIGHT; y++) {   
+    for(size_t x = 0; x < VGA_WIDTH; x++) {
+      const size_t ind = y * VGA_WIDTH + x;
+      term_buf[ind] = vga_entry(' ', term_color);
+    }
+  }
+}
+
+void term_scroll(void) {
+  for(size_t y = 0; y < VGA_HEIGHT; y++) {
+    for(size_t x = 0; x < VGA_WIDTH; x++) {
+      const size_t ind = y * VGA_WIDTH + x;
+      term_buf[ind] = term_buf[(y+1) * VGA_WIDTH + x];
+    }
+  }
+
+  for(size_t x = 0; x < VGA_WIDTH; x++) {
+    const size_t ind = VGA_HEIGHT * VGA_WIDTH + x;
+    term_buf[ind] = vga_entry(' ', term_color);
+  }
+}
+
+void term_setcolor(uint8_t color) {
+  term_color = color;
+}
+
+void term_putentryat(unsigned char c, uint8_t color, size_t x, size_t y) {
+  const size_t ind = y * VGA_WIDTH + x;
+  term_buf[ind] = vga_entry(c, color);
+}
+
+void term_putc(char c) {
+  unsigned char uc = c;
+  if(term_row > VGA_HEIGHT) {
+    term_scroll();
+    term_row--;
+  }
+  switch(uc) {
+    case '\n': term_row++; term_col = 0; break;
+    default: term_putentryat(uc, term_color, term_col, term_row); break;
+  }
+  
+  if(uc != '\n' && ++term_col == VGA_WIDTH) {
+    term_col = 0;
+    if(++term_row == VGA_HEIGHT) {
+      term_scroll();
+    }
+  }
+}
+
+void term_write(const char* str, size_t size) {
+  for(size_t i = 0; i < size; i++) {
+    term_putc(str[i]);
+  }
+}
+
+void term_writestr(const char* str) {
+  term_write(str, strlen(str));
+}
diff --git a/arch/i386/vga.h b/arch/i386/vga.h
new file mode 100755
index 0000000..f97e80e
--- /dev/null
+++ b/arch/i386/vga.h
@@ -0,0 +1,33 @@
+#ifndef _ARCH_I386_VGA_H
+#define _ARCH_I386_VGA_H
+
+#include <stdint.h>
+
+enum vga_color {
+		VGA_COLOR_BLACK = 0,
+		VGA_COLOR_BLUE= 1,
+		VGA_COLOR_GREEN = 2,
+		VGA_COLOR_CYAN = 3,
+		VGA_COLOR_RED = 4,
+		VGA_COLOR_MAGENTA = 5,
+		VGA_COLOR_BROWN = 6,
+		VGA_COLOR_LIGHT_GREY = 7,
+		VGA_COLOR_DARK_GREY = 8,
+		VGA_COLOR_LIGHT_BLUE = 9,
+		VGA_COLOR_LIGHT_GREEN = 10,
+		VGA_COLOR_LIGHT_CYAN = 11,
+		VGA_COLOR_LIGHT_RED = 12,
+		VGA_COLOR_LIGHT_MAGENTA = 13,
+		VGA_COLOR_LIGHT_BROWN = 14,
+		VGA_COLOR_WHITE = 15,
+};
+
+static inline uint8_t vga_entry_color(enum vga_color fg, enum vga_color bg) {
+  return fg | bg << 4;
+}
+
+static inline uint16_t vga_entry(unsigned char uc, uint8_t color) {
+  return (uint16_t) uc | (uint16_t) color << 8;
+}
+
+#endif
diff --git a/include/kernel/tty.h b/include/kernel/tty.h
new file mode 100755
index 0000000..35218b4
--- /dev/null
+++ b/include/kernel/tty.h
@@ -0,0 +1,12 @@
+#ifndef _KERN_TTY_H
+#define _KERN_TTY_H
+
+#include <stddef.h>
+
+void term_init(void);
+void term_scroll(void);
+void term_putc(char c);
+void term_write(const char* str, size_t size);
+void term_writestr(const char* str);
+
+#endif