misc: C++->CHEADmain

I know; it's POINTLESS! However, I do enjoy programming in C more than
C++ so I ended up spending the hour it takes converting this project
from C++ to C.

1 files changed, 99 insertions, 0 deletions

diff --git a/kernel/drivers/vga_text_buffer.c b/kernel/drivers/vga_text_buffer.c
new file mode 100644
index 0000000..ee0a1ea
--- /dev/null
+++ b/kernel/drivers/vga_text_buffer.c
@@ -0,0 +1,99 @@
+/*
+ * bubbl
+ * Copyright (C) 2024-2025  Raghuram Subramani <raghus2247@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <common.h>
+
+#include <libk/stdio.h>
+#include <libk/string.h>
+
+#include <kernel/io.h>
+
+#include <drivers/vga_text_buffer.h>
+
+static uint16_t *l_buffer = (uint16_t *) 0xB8000;
+static uint8_t l_row = 0;
+static uint8_t l_column = 0;
+static uint8_t l_color = vga_entry_color(COLOR_LIGHT_GREY, COLOR_BLACK);
+
+ALWAYS_INLINE static void
+write_entry_at(const char c,
+               const uint8_t color,
+               const uint8_t x,
+               const uint8_t y)
+{
+  size_t index = y * VGA_WIDTH + x;
+  l_buffer[index] = vga_entry(c, color);
+}
+
+void
+vgatb_initialize(void)
+{
+  /*
+   * Disable the cursor
+   * TODO: Abstract this and all other cursor functionality out
+   */
+  outb(0x3D4, 0x0A);
+  outb(0x3D5, 0x20);
+
+  for (uint8_t y = 0; y < VGA_HEIGHT; y++)
+    for (uint8_t x = 0; x < VGA_WIDTH; x++)
+      write_entry_at(' ', l_color, x, y);
+}
+
+void
+vgatb_write_char(const char c)
+{
+  if (c == '\n') {
+    l_row++;
+    l_column = 0;
+  } else {
+    write_entry_at(c, l_color, l_column, l_row);
+
+    if (++l_column == VGA_WIDTH) {
+      l_column = 0;
+      if (++l_row == VGA_HEIGHT)
+        l_row = 0;
+    }
+  }
+}
+
+void
+vgatb_write_string(const char *string)
+{
+  size_t size = strlen(string);
+  for (size_t i = 0; i < size; i++)
+    vgatb_write_char(string[i]);
+}
+
+void
+vgatb_printf(const char *string, ...)
+{
+  /* TODO: Dynamic Memory Allocation */
+  char str[256];
+
+  va_list ap;
+  va_start(ap, string);
+  vsnprintf(str, sizeof(str), string, ap);
+  va_end(ap);
+
+  vgatb_write_string(str);
+}