introduce printf for screen text memory

Makefile

@@ -33,7 +33,7 @@ $(BUILD_DIR)/%.asm.o: $(SRC_DIR)/%.asm
 
 $(BUILD_DIR)/%.c.o: $(SRC_DIR)/%.c
 	@mkdir -p "$(@D)"
-	$(CC) -c $< -o $@ -I$(INCLUDE_DIR) -std=gnu99 -ffreestanding -O2 -Wall -Wextra
+	$(CC) -c $< -o $@ -I$(INCLUDE_DIR) -std=gnu99 -ffreestanding -O2 -Wall -Wextra -Wformat
 
 clean:
 	rm -rf $(BUILD_DIR)/*

src/kernel/include/internal/text_screen.h

@@ -36,4 +36,7 @@ void tsinit(void);
 void tsputch(char ch, uint8_t color);
 void tsputs(const char* str, uint8_t color);
 
+void tsprintf(const char* format, ...)
+	__attribute__((format (printf, 1, 2)));
+
 #endif // _CLIPPER_TEXT_SCREEN_H_

src/kernel/kmain.c

@@ -16,8 +16,10 @@
 void kmain(void) {
 	tsinit();
 
-	const char* msg = "Clipper set sail!\n~~~~~~~~~~~~~~~~~";
+	const char* msg = "Clipper set sail!\n~~~~~~~~~~~~~~~~~\n";
 	tsputs(msg, TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_LIGHT_CYAN);
 
+	tsprintf("Test | Integers: %d, Unsigned: %u, Hexadecimal: %x\n", -48, 28493, 28493);
+
 	return;
 }

src/kernel/lib/text_screen.c

@@ -1,5 +1,8 @@
 #include "internal/text_screen.h"
+
+#include <stdarg.h>
 #include "internal/io.h"
+#include "stdlib.h"
 
 struct text_screen_char {
 	char character;
@@ -13,6 +16,13 @@ static uint8_t cursor_y = 0;
 #define SCREEN_WIDTH 80
 #define SCREEN_HEIGHT 25
 
+enum printf_format_specifier {
+	FORMAT_SPECIFIER_INT,
+	FORMAT_SPECIFIER_UNSIGNED,
+	FORMAT_SPECIFIER_HEXADECIMAL,
+	FORMAT_SPEFICIER_UNKNOWN
+};
+
 void tsinit(void) {
 	outb(0x3D4, 0x0A);
 	outb(0x3D5, 0x20);
@@ -23,7 +33,8 @@ void tsputch(char ch, uint8_t color) {
 	tsputs(tmp, color);
 }
 
-static void handle_special_char(char c) {
+static 
+void handle_special_char(char c) {
 	switch (c) {
 		case '\n': {
 			cursor_x = 0;
@@ -66,3 +77,93 @@ void tsputs(const char* ch, uint8_t color) {
 		}
 	}
 }
+
+static 
+const char* decode_format_spefifier(const char* str, enum printf_format_specifier* data) {
+	switch (*str) {
+		case 'd':
+		case 'i':
+			*data = FORMAT_SPECIFIER_INT;
+			return str+1;
+
+		case 'o':
+		case 'u':
+			*data = FORMAT_SPECIFIER_UNSIGNED;
+			return str+1;
+
+		case 'x':
+		case 'X':
+			*data = FORMAT_SPECIFIER_HEXADECIMAL;
+			return str+1;
+	}
+
+	*data = FORMAT_SPEFICIER_UNKNOWN;
+	return str;
+}
+
+static 
+const char* handle_format_specifier(const char* str, va_list* args) {
+	str++;
+	char tmp[16];
+	
+	enum printf_format_specifier specifier;
+	str = decode_format_spefifier(str, &specifier);
+	switch (specifier) {
+		case FORMAT_SPECIFIER_INT: {
+			int value = va_arg(*args, int);
+			tsputs(itoa(value, tmp, 10), TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_WHITE);
+		} break;
+
+		case FORMAT_SPECIFIER_UNSIGNED: {
+			unsigned int value = va_arg(*args, unsigned int);
+			tsputs(utoa(value, tmp, 10), TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_WHITE);
+		} break;
+
+
+		case FORMAT_SPECIFIER_HEXADECIMAL: {
+			unsigned int value = va_arg(*args, unsigned int);
+			tsputs(utoa(value, tmp, 16), TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_WHITE);
+		} break;
+		default: return str;
+	}
+
+	return str-1;
+}
+
+void tsprintf(const char* format, ...) {
+	struct text_screen_char tsch = {
+		.character = '\0',
+		.attribute = TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_GRAY
+	};
+
+	va_list args;
+	va_start(args, format);
+
+	for (const char* c = format; *c != '\0'; c++) {
+		if (*c == '%') {
+			c = handle_format_specifier(c, &args);
+			continue;
+		}
+
+		if ((uint8_t)(*c) < 0x20) {
+			handle_special_char(*c);
+			continue;
+		}
+
+		tsch.character = *c;
+
+		videomem[cursor_y * SCREEN_WIDTH + cursor_x] = tsch;
+
+		cursor_x++;
+		if (cursor_x >= SCREEN_WIDTH) {
+			cursor_y++;
+			cursor_x = 0;
+
+			if (cursor_y >= SCREEN_HEIGHT) {
+				cursor_y = 0;	
+			}
+		}
+	}
+
+	va_end(args);
+}