First working version! Basic hello world kernel.

kernel/brados.c

@@ -0,0 +1,104 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+// Make sure we are using the right compiler
+#if defined(__linux__)
+#error "You are using the wrong compiler."
+#endif
+
+// Color constants
+enum vgaColor
+{
+	COLOR_BLACK = 0,
+	COLOR_BLUE = 1,
+	COLOR_GREEN = 2,
+	COLOR_CYAN = 3,
+	COLOR_RED = 4,
+	COLOR_MAGENTA = 5,
+	COLOR_BROWN = 6,
+	COLOR_LIGHT_GREY = 7,
+	COLOR_DARK_GREY = 8,
+	COLOR_LIGHT_BLUE = 9,
+	COLOR_LIGHT_GREEN = 10,
+	COLOR_LIGHT_CYAN = 11,
+	COLOR_LIGHT_RED = 12,
+	COLOR_LIGHT_MAGENTA = 13,
+	COLOR_LIGHT_BROWN = 14,
+	COLOR_WHITE = 15
+};
+
+uint8_t makeColor(enum vgaColor fg, enum vgaColor bg)
+{
+	return fg | bg << 4;
+}
+
+uint16_t makeVGAEntry(char c, uint8_t color)
+{
+	uint16_t c16 = c;
+	uint16_t color16 = color;
+	return c16 | color16 << 8;
+}
+
+size_t strlen(const char *str)
+{
+	size_t len = 0;
+	while (str[len] != 0)
+		len++;
+	return len;
+}
+
+static const size_t VGA_WIDTH = 80;
+static const size_t VGA_HEIGHT = 24;
+
+size_t terminalRow, terminalCol;
+uint8_t terminalColor;
+uint16_t *terminalBuf;
+
+void terminalInit()
+{
+	terminalRow = terminalCol = 0;
+	terminalColor = makeColor(COLOR_LIGHT_GREY, COLOR_BLACK);
+	terminalBuf = (uint16_t *) 0xB8000;
+	
+	for (size_t x = 0; x < VGA_WIDTH; x++) {
+		for (size_t y = 0; y < VGA_HEIGHT; y++) {
+			const size_t index = y * VGA_WIDTH + x;
+			terminalBuf[index] = makeVGAEntry(' ', terminalColor);
+		}
+	}
+}
+
+void terminalSetColor(uint8_t color)
+{
+	terminalColor = color;
+}
+
+void terminalPutEntryAt(char c, uint8_t color, size_t x, size_t y)
+{
+	const size_t index = y * VGA_WIDTH + x;
+	terminalBuf[index] = makeVGAEntry(c, color);
+}
+
+void terminalPutChar(char c)
+{
+	terminalPutEntryAt(c, terminalColor, terminalCol, terminalRow);
+	if (terminalCol++ == VGA_WIDTH) {
+		terminalCol = 0;
+		if (terminalRow++ == VGA_HEIGHT)
+			terminalRow = 0;
+	}
+}
+
+void terminalWriteString(const char *data)
+{
+	size_t dataLen = strlen(data);
+	for (size_t i = 0; i < dataLen; i++)
+		terminalPutChar(data[i]);
+}
+
+void brados_main()
+{
+	terminalInit();
+	terminalWriteString("Welcome to BRaDOS!\n");
+}