Terminal printf, drawing strings, this is such a W upgrade!!

1 files changed, 85 insertions, 6 deletions

diff --git a/src/kernel.c b/src/kernel.c
index 615f02a..28b1dc8 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -4,6 +4,7 @@ This software is licensed under the ARPL. See LICENSE for details. */
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
+#include "font8x8_basic.h"
 
 /* check if compiler thinks we are targeting incorrect OS. */
 #if defined(__linux__)
@@ -15,6 +16,13 @@ This software is licensed under the ARPL. See LICENSE for details. */
 #error "this operating system is only supported on ix86 targets. use an elf cross-compiler for ix86 targets, for example, i386-elf-gcc"
 #endif
 
+static int term_col = 0;
+static int term_row = 0;
+static uint32_t *g_framebuffer = NULL;
+static uint32_t g_width = 0;
+static uint32_t g_height = 0;
+static uint32_t g_default_color = 0xFFFFFF;
+
 /* what in the dark magic? ok just dont touch one can hope */
 struct multiboot_info {
 	uint32_t flags;
@@ -47,6 +55,68 @@ struct multiboot_info {
 	uint8_t  color_info[6];
 } __attribute__((packed));
 
+void draw_char(int x, int y, int c, uint32_t color, uint32_t *framebuffer, uint32_t width)
+{
+	char *glyph = font8x8_basic[(unsigned char)c];
+
+	for (int row = 0; row < 8; row++) {
+		for (int col = 0; col < 8; col++) {
+			if (glyph[row] & (1 << col)) {
+				framebuffer[(y + row) * width + (x + col)] = color;
+			}
+		}
+	}
+}
+
+void draw_string(int x, int y, const char *str, uint32_t color, uint32_t *framebuffer, uint32_t width)
+{
+	while (*str) {
+		draw_char(x, y, *str, color, framebuffer, width);
+		x += 8;
+		str++;
+	}
+}
+
+void term_init(uint32_t *framebuffer, uint32_t width, uint32_t height)
+{
+	g_framebuffer = framebuffer;
+	g_width = width;
+	g_height = height;
+	term_col = 0;
+	term_row = 0;
+}
+
+void term_set_color(uint32_t color)
+{
+	g_default_color = color;
+}
+
+void term_printf(const char *str)
+{
+	while (*str) {
+		if (*str == '\n') {
+			term_col = 0;
+			term_row++;
+			str++;
+			continue;
+		}
+
+		if ((term_col * 8) >= g_width) {
+			term_col = 0;
+			term_row++;
+		}
+
+		if ((term_row * 8) >= g_height) {
+			term_row = 0; // just simple wrap around for now, scroll later
+		}
+
+		draw_char(term_col * 8, term_row * 8, *str, g_default_color, g_framebuffer, g_width);
+
+		term_col++;
+		str++;
+	}
+}
+
 void kernel_main(struct multiboot_info *mbi) 
 {
 	// check if framebuffer info is available (bit 12)
@@ -54,17 +124,26 @@ void kernel_main(struct multiboot_info *mbi)
 		while(1) __asm__("hlt");
 	}
 
+	// get the framebuffer
 	uint32_t *framebuffer = (uint32_t*)(uintptr_t)mbi->framebuffer_addr;
 	uint32_t width = mbi->framebuffer_width;
 	uint32_t height = mbi->framebuffer_height;
-	uint32_t pitch = mbi->framebuffer_pitch;
 
-	for (uint32_t y = 0; y < height; y++) {
-		for (uint32_t x = 0; x < width; x++) {
-		    framebuffer[y * (pitch / 4) + x] = 0x00FFFF00;
-		}
-	}
+	// draw text to the framebuffer
+	term_init(framebuffer, width, height);
+	term_printf("welcome to ");
+	term_set_color(0xFCD24D);
+	term_printf("FrenchToastOS!\n");
+	term_set_color(0xFFFFFF);
+	term_printf("developed by ");
+	term_set_color(0x967BB6);
+	term_printf("Arslaan Pathan\n");
+	term_set_color(0xFFFFFF);
+	term_printf("---\n");
+	term_printf("https://arslaancodes.com\n");
 
+	// if theres nothing left to do, halt the cpu or else cooked
+	// our boot.s already does this but better to be safe than sorry
 	while (1) {
 		__asm__ __volatile__ ("hlt");
 	}