From 9b2a78fa52249ab481493550490aa5f37872dcf6 Mon Sep 17 00:00:00 2001
From: aqua <aqua@iserlohn-fortress.net>
Date: Sat, 10 Dec 2022 20:56:57 +0200
Subject: Rewrite drivers/uart and drivers/vga in cpp

---
 devices/vga.cpp | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)
 create mode 100644 devices/vga.cpp

(limited to 'devices/vga.cpp')

diff --git a/devices/vga.cpp b/devices/vga.cpp
new file mode 100644
index 0000000..3f83a5f
--- /dev/null
+++ b/devices/vga.cpp
@@ -0,0 +1,138 @@
+#include "vga.hpp"
+#include <stdint.h>
+#include <sys/io.h>
+
+// FIXME user a Port
+#define cga_idx_port 0x3d4
+#define cga_dat_port 0x3d5
+
+// FIXME make constexpr
+#define cursor_start 0x0a
+#define cursor_end 0x0b
+#define cursor_addr_h 0x0e
+#define cursor_addr_l 0x0f
+#define cursor_hide 0x20
+
+static_assert(sizeof(struct VGA::VGAEntry) == 2, "sizeof VGAEntry");
+
+// FIXME make constexpr
+const int width = 80;
+const int height = 25;
+
+// *** Cursor ***
+// FIXME make VGA members
+void
+vga_enable_cursor(unsigned char start, unsigned char end)
+{
+  outb(cursor_start, cga_idx_port);
+  outb((inb(cga_dat_port) & 0xc0) | start, cga_dat_port);
+
+  outb(cursor_end, cga_idx_port);
+  outb((inb(cga_dat_port) & 0xe0) | end, cga_dat_port);
+}
+
+void
+vga_disable_cursor()
+{
+  outb(cursor_start, cga_idx_port);
+  outb(cursor_hide, cga_dat_port);
+}
+
+void
+VGA::update_cursor()
+{
+  const uint16_t pos = row * width + col;
+
+  outb(cursor_addr_l, cga_idx_port);
+  outb(pos & 0xff, cga_dat_port);
+
+  outb(cursor_addr_h, cga_idx_port);
+  outb((pos >> 8) & 0xff, cga_dat_port);
+}
+
+// *** Text Mode Output ***
+void
+VGA::putc(char a)
+{
+  switch (a) {
+  case '\n':
+    col = 0;
+    ++row;
+    break;
+  case '\r':
+    col = 0;
+    break;
+  case '\b':
+    --col;
+    if (col < 0) col = 0;
+    break;
+  default:
+    buffer[row * width + col].text = a;
+    ++col;
+  }
+
+  if (col == width) {
+    col = 0;
+    ++row;
+  }
+
+  if (row == height) {
+    // scroll up
+    for (int y = 1; y < height; ++y)
+      for (int x = 0; x < width; ++x) {
+        const int prev = (y - 1) * width + x;
+        const int curr = y * width + x;
+        buffer[prev] = buffer[curr];
+      }
+    // blank out last row
+    for (int i = (height - 1) * width; i < height * width; ++i) buffer[i].text = ' ';
+    --row;
+  }
+}
+
+int
+VGA::puts(const char *string, int len)
+{
+  int written = 0;
+  if (len == -1)
+    while (*string != '\0') {
+      putc(*string);
+      ++string;
+      ++written;
+    }
+
+  else
+    for (int i = 0; i < len; ++i) {
+      putc(string[i]);
+      ++written;
+    }
+  return written;
+}
+
+// *** Text Mode ***
+VGA::VGA(void *addr)
+{
+  buffer = (struct VGAEntry *)addr;
+  vga_enable_cursor(14, 15);
+  clear(VGA_COLOR_LIGHT_BLUE, VGA_COLOR_LIGHT_GREY);
+}
+FILE *
+vga_init(void *buffer)
+{
+  static VGA device(buffer);
+  return &device;
+}
+
+void
+VGA::clear(enum vga_color foreground, enum vga_color background)
+{
+  for (int y = 0; y < height; ++y)
+    for (int x = 0; x < width; ++x) {
+      const int index = y * width + x;
+      buffer[index].text = ' ';
+      buffer[index].foreground = foreground;
+      buffer[index].background = background;
+    }
+  col = row = 0;
+  update_cursor();
+}
-- 
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