From d835cae0968ea5d6e9989dac637449b8d403ac5e Mon Sep 17 00:00:00 2001
From: Joursoir <chat@joursoir.net>
Date: Mon, 30 Aug 2021 12:48:24 +0000
Subject: move interaction with VGA to driver

---
 drivers/video/console/vgacon.c | 101 +++++++++++++++++++++++++++++++++++++++++
 drivers/video/console/vgacon.h |  15 ++++++
 2 files changed, 116 insertions(+)
 create mode 100644 drivers/video/console/vgacon.c
 create mode 100644 drivers/video/console/vgacon.h

(limited to 'drivers/video')

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
new file mode 100644
index 0000000..cad384a
--- /dev/null
+++ b/drivers/video/console/vgacon.c
@@ -0,0 +1,101 @@
+/*
+	Low level VGA based console driver
+*/
+
+#include "string.h"
+#include "video/vga.h"
+#include "asm/io.h"
+
+#define LIGHT_GREY_ON_BLACK \
+	VGA_ENTRY_COLOR(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK)
+
+static uint16_t *vga_vram_base;
+static size_t vga_vram_size;
+static size_t vga_cols;
+static size_t vga_rows;
+static uint8_t vga_attr;
+
+static size_t cursor_x;
+static size_t cursor_y;
+
+void vgacon_init(void)
+{
+	vga_vram_base = (uint16_t *) VGA_VRAM_BC;
+	vga_cols = 80;
+	vga_rows = 25;
+	vga_vram_size = vga_cols * vga_rows;
+	vga_attr = LIGHT_GREY_ON_BLACK;
+
+	cursor_x = 0;
+	cursor_y = 0;
+}
+
+void vgacon_setattr(uint8_t attr)
+{
+	vga_attr = attr;
+}
+
+void vgacon_scroll(size_t lines)
+{
+	uint16_t vga_char = VGA_ENTRY(' ', vga_attr);
+	size_t count = (vga_rows - lines) * vga_cols;
+	memmove(vga_vram_base, vga_vram_base + vga_cols * lines, count * 2);
+	for(; count < vga_vram_size; count++)
+		vga_vram_base[count] = vga_char;
+}
+
+void vgacon_cls(void)
+{
+	vgacon_scroll(vga_rows);
+}
+
+static void putchar(char c)
+{
+	if(c == '\n') {
+		cursor_x = 0;
+		if(++cursor_y >= vga_rows) {
+			vgacon_scroll(1);
+			cursor_y--;
+		}	
+	}
+	else {
+		const size_t index = cursor_y * vga_cols + cursor_x;
+		vga_vram_base[index] = VGA_ENTRY(c, vga_attr);
+
+		if(++cursor_x >= vga_cols) {
+			cursor_x = 0;
+			if(++cursor_y >= vga_rows) {
+				vgacon_scroll(1);
+				cursor_y--;
+			}
+		}
+	}
+}
+
+static void update_cursor()
+{
+	uint16_t pos = cursor_y * vga_cols + cursor_x;
+	outb(VGA_CRTC_IC, VGA_CRTC_CURSOR_H);
+	outb(VGA_CRTC_DC, (uint8_t) ((pos >> 8) & 0xFF));
+	outb(VGA_CRTC_IC, VGA_CRTC_CURSOR_L);
+	outb(VGA_CRTC_DC, (uint8_t) (pos & 0xFF));
+}
+
+void vgacon_putchar(char c)
+{
+	putchar(c);
+	update_cursor();
+}
+
+void vgacon_write(const char *str, size_t size)
+{
+	size_t i;
+	for(i = 0; i < size; i++)
+		putchar(str[i]);
+	update_cursor();
+}
+
+void vgacon_print(const char *str)
+{
+	vgacon_write(str, strlen(str));
+}
diff --git a/drivers/video/console/vgacon.h b/drivers/video/console/vgacon.h
new file mode 100644
index 0000000..ac2e9e3
--- /dev/null
+++ b/drivers/video/console/vgacon.h
@@ -0,0 +1,15 @@
+#ifndef DRIVERS_VIDEO_CONSOLE_VGA_H
+#define DRIVERS_VIDEO_CONSOLE_VGA_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+void vgacon_init(void);
+void vgacon_setattr(uint8_t attr);
+void vgacon_scroll(size_t lines);
+void vgacon_cls(void);
+void vgacon_putchar(char c);
+void vgacon_write(const char *str, size_t size);
+void vgacon_print(const char *str);
+
+#endif /* DRIVERS_VIDEO_CONSOLE_VGA_H */
-- 
cgit v1.2.3-18-g5258