1 files changed, 93 insertions, 0 deletions
diff --git a/src/vga.c b/src/vga.c
new file mode 100644
index 0000000..71faa1a
--- /dev/null
+++ b/src/vga.c
@@ -0,0 +1,93 @@
+#include<stdbool.h>
+#include<stddef.h>
+#include<stdint.h>
+#include"vga.h"
+static const size_t VGA_WIDTH = 80;
+static const size_t VGA_HEIGHT = 25;
+
+extern char ioport_in(uint8_t port);
+extern void ioport_out(uint8_t port, char data);
+
+bool stringcmp(char *str1,char *str2);
+
+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;
+}
+ 
+size_t terminal_row;
+size_t terminal_column;
+uint8_t terminal_color;
+uint16_t* terminal_buffer;
+ 
+void terminal_initialize()
+{
+    terminal_row=0;
+    terminal_column=0;
+    terminal_color=vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
+    terminal_buffer=(uint16_t*) 0xB8000;
+    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 terminal_putentryat(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 movescreen()
+{
+    terminal_row--;
+    for(size_t i=0;i<VGA_HEIGHT;i++) for(size_t j=0;j<VGA_WIDTH;j++) terminal_buffer[i*VGA_WIDTH+j]=terminal_buffer[(i+1)*VGA_WIDTH+j];
+}
+
+void next_field()
+{
+    if(++terminal_column==VGA_WIDTH) terminal_column=0,terminal_row++;
+}
+
+void previous_field()
+{
+    if(terminal_column) terminal_column--;
+    else terminal_row--,terminal_column=VGA_WIDTH-1;
+}
+ 
+void terminal_putchar(char c)
+{
+    if(c=='\n') terminal_column=0,terminal_row++;
+    else
+    {
+	terminal_putentryat(c, terminal_color, terminal_column, terminal_row);
+	next_field();
+    }
+    if (terminal_row==VGA_HEIGHT) movescreen();
+}
+ 
+void terminal_writestring(const char* data)
+{
+    for(int i=0;data[i]!='\0';i++) terminal_putchar(data[i]);
+}
+
+void prompt()
+{
+    terminal_writestring("[user@myos] > ");
+}
+
+void clear()
+{
+    for(size_t i=0;i<VGA_HEIGHT;i++) for(size_t j=0;j<VGA_WIDTH;j++) terminal_putchar(' ');
+    terminal_column=0;
+    terminal_row=0;
+}