Added printf().

5 files changed, 110 insertions, 19 deletions

diff --git a/kernel/SConscript b/kernel/SConscript
index 856d2b5..8c17467 100644
--- a/kernel/SConscript
+++ b/kernel/SConscript
@@ -27,4 +27,4 @@ kernel_bld = Builder(
 
 env.Append(BUILDERS = {'Kernel' : kernel_bld})
 
-kernel = env.Kernel('kernel', ['kernel.ld', 'entry.c', 'main.c', 'gdt.c', 'idt.c'])
+kernel = env.Kernel('kernel', ['kernel.ld', 'entry.c', 'main.c', 'printf.c', 'gdt.c', 'idt.c'])
diff --git a/kernel/main.c b/kernel/main.c
index cc0dc35..55476ce 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -1,19 +1,17 @@
+#include "printf.h"
 #include "gdt.h"
 #include "idt.h"
 
-void kernel_serial_out(char* str);
-
 void main() {
-	
-	kernel_serial_out("main()\n");
+	printf("main()\n");
 	
 	gdt_init();
-	kernel_serial_out("GDT set.\n");
+	printf("GDT set.\n");
 	
 	idt_init();
-	kernel_serial_out("IDT set.\n");
+	printf("IDT set.\n");
 	
-	kernel_serial_out("Halting.\n");
+	printf("Halting.\n");
 	
 	asm volatile(
 		"cli\n"
@@ -21,14 +19,3 @@ void main() {
 	);
 	while(1);
 }
-
-#define outb(port, value) asm volatile("out %b0,%w1" : : "a" (value), "d" (port));
-
-void kernel_serial_out(char* str) {
-	while(*str) {
-		if(*str == '\n') {
-			outb(0x3f8, '\r');
-		}
-		outb(0x3f8, *str++);
-	}
-}
diff --git a/kernel/printf.c b/kernel/printf.c
new file mode 100644
index 0000000..4b3a632
--- /dev/null
+++ b/kernel/printf.c
@@ -0,0 +1,96 @@
+#include "printf.h"
+#include "types.h"
+
+#define outb(port, value) asm volatile("out %b0,%w1" : : "a" (value), "d" (port));
+
+void putchar(char c) {
+	if(c == '\n') {
+		outb(0x3f8, '\r');
+	}
+	outb(0x3f8, c);
+}
+
+int printf(const char* format, ...) {
+	int32_t* argp = (int32_t*)&format;
+	int num;
+	
+	while(*format) {
+		if(*format != '%') {
+			putchar(*format++);
+			num++;
+			continue;
+		}
+		format++;
+		
+		bool is_signed = false;
+		bool zero_pad = false;
+		int radix = 16;
+		int min_len = 0;
+		
+		if(*format == '0') {
+			zero_pad = true;
+		}
+		
+		while(*format >= '0' && *format <= '9') {
+			min_len = min_len * 10 + *format++ - '0';
+		}
+		
+		switch(*format++) {
+			case '%':
+				putchar('%');
+				num++;
+				break;
+			
+			case 'c':
+				putchar((char)*++argp);
+				num++;
+				break;
+			
+			case 's':
+				;
+				char* str = (char*)*++argp;
+				while(*str) {
+					putchar(*str++);
+					num++;
+				}
+				break;
+			
+			case 'd':
+				is_signed = true;
+			case 'u':
+				radix = 10;
+			case 'x':
+				;
+				uint32_t x = (uint32_t)*(++argp);
+				if(is_signed && (int32_t)x < 0) {
+					x = -x;
+					putchar('-');
+					min_len--;
+				}
+				
+				char buf[11];
+				char* bufp = &buf[sizeof(buf)];
+				*--bufp = 0;
+				
+				do {
+					int d = x % radix;
+					*--bufp = d < 10 ? '0' + d : 'a' - 10 + d;
+					x /= radix;
+					min_len--;
+				} while(x);
+				
+				while(min_len > 0) {
+					putchar(zero_pad ? '0' : ' ');
+					num++;
+					min_len--;
+				}
+				
+				while(*bufp) {
+					putchar(*bufp++);
+					num++;
+				}
+				break;
+		}
+	}
+	return num;
+}
diff --git a/kernel/printf.h b/kernel/printf.h
new file mode 100644
index 0000000..16d612c
--- /dev/null
+++ b/kernel/printf.h
@@ -0,0 +1,6 @@
+#ifndef PRINTF_H
+#define PRINTF_H
+
+int printf(const char* format, ...);
+
+#endif
diff --git a/kernel/types.h b/kernel/types.h
index 4fdca6b..a200526 100644
--- a/kernel/types.h
+++ b/kernel/types.h
@@ -8,4 +8,6 @@ typedef unsigned short uint16_t;
 typedef signed int int32_t;
 typedef unsigned int uint32_t;
 
+typedef enum {false, true} bool;
+
 #endif