Implemented UART and created its printf-like function

src/kernel/drivers/serial.c

@@ -1,42 +0,0 @@
-#include "serial.h"
-#include "../arch/i686/io.h"
-
-int serial_initialize(uint8_t port){
-    i686_outb(port + 1, 0x00); // Disable all interrupts
-    i686_outb(port + 3, 0x80); // Enable DLAB
-    i686_outb(port + 0, 0x03); // Divisor high byte (38400 baud)
-    i686_outb(port + 1, 0x00); // Divisor low byte
-    i686_outb(port + 3, 0x03); // 8 bits, no parity, one stop bit
-    i686_outb(port + 2, 0xC7); // Enable FIFO
-    i686_outb(port + 4, 0x0B); // IRQs enabled, RTS/DSR set
-    
-    i686_outb(port + 4, 0x1E); // Loopback mode, test serial chip
-    i686_outb(port + 0, 0xAE); // Test serial chip sending 0xAE
-    
-    if(i686_inb(port + 0) != 0xAE){ // Not working
-        return 1;
-    }
-
-    i686_outb(port + 4, 0x0F); // Normal operation mode
-    return 0;
-}
-
-static int serial_received(uint8_t port){
-    return i686_inb(port + 5) & 0x01;
-}
-
-char serial_read(uint8_t port){
-    while(!serial_received(port));
-
-    return i686_inb(port);
-}
-
-static int serial_tx_empty(uint8_t port){
-    return i686_inb(port + 5) & 0x20;
-}
-
-void serial_write(uint8_t port, char c){
-    while(!serial_tx_empty(port));
-
-    return i686_outb(port, c);
-}

src/kernel/drivers/serial.h

@@ -1,16 +0,0 @@
-#pragma once
-
-#include <stdint.h>
-
-#define COM1 (uint8_t)0x3F8
-#define COM2 (uint8_t)0x2F8
-#define COM3 (uint8_t)0x3E8
-#define COM4 (uint8_t)0x2E8
-#define COM5 (uint8_t)0x5F8
-#define COM6 (uint8_t)0x4F8
-#define COM7 (uint8_t)0x5E8
-#define COM8 (uint8_t)0x4E8
-
-int serial_initialize(uint8_t port);
-char serial_read(uint8_t port);
-void serial_write(uint8_t port, char c);

src/kernel/drivers/uart.c

@@ -0,0 +1,41 @@
+#include "uart.h"
+#include "../arch/i686/io.h"
+
+void uart_set_baudrate(uint16_t port, uint16_t divisor){
+    i686_outb(port + 3, 0x80); // Enable DLAB
+    i686_outb(port, (divisor >> 8) & 0x00FF); // High part
+    i686_outb(port, divisor & 0x00FF); // Low part
+}
+
+void uart_initialize(uint16_t port, uint16_t baudrate_div){
+    uart_set_baudrate(port, baudrate_div);
+
+    // Configure line
+    i686_outb(port + 3, 0x03); // 8 bit, no parity, 1 stop bit, no break control
+
+    // Configure buffering
+    i686_outb(port + 2, 0xC7); // FIFO enabled, clear both FIFO queues, 14 bytes queue(s)
+
+    // Configure modem
+    i686_outb(port + 4, 0x03); // RTS=1 DTS=1
+}
+
+static int uart_received(uint16_t port){
+    return i686_inb(port + 5) & 0x01;
+}
+
+char uart_read(uint16_t port){
+    while(!uart_received(port));
+
+    return i686_inb(port);
+}
+
+static int uart_tx_empty(uint16_t port){
+    return i686_inb(port + 5) & 0x20;
+}
+
+void uart_write(uint16_t port, char c){
+    while(!uart_tx_empty(port));
+
+    return i686_outb(port, c);
+}

src/kernel/drivers/uart.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <stdint.h>
+
+#define COM1 (uint16_t)0x3F8
+#define COM2 (uint16_t)0x2F8
+#define COM3 (uint16_t)0x3E8
+#define COM4 (uint16_t)0x2E8
+#define COM5 (uint16_t)0x5F8
+#define COM6 (uint16_t)0x4F8
+#define COM7 (uint16_t)0x5E8
+#define COM8 (uint16_t)0x4E8
+
+void uart_set_baudrate(uint16_t port, uint16_t divisor);
+void uart_initialize(uint16_t port, uint16_t baudrate_div);
+char uart_read(uint16_t port);
+void uart_write(uint16_t port, char c);

src/kernel/lib/stdio.c

@@ -2,6 +2,9 @@
 #include <stdbool.h>
 #include "stdio.h"
 #include "../drivers/vga.h"
+#include "../drivers/uart.h"
+
+typedef void (*print_callable_fn_t)(char);
 
 static char g_HexChars[] = "0123456789abcdef";
 
@@ -16,7 +19,11 @@ void putc(char c){
     vga_print_string(str);
 }
 
-static void printf_unsigned(unsigned long long num, int radix){
+void serial_putc(char c){
+    uart_write(COM1, c); // TODO: Add an option to decide what COM to use
+}
+
+static void printf_unsigned(print_callable_fn_t out_fn, unsigned long long num, int radix){
     char buffer[32];
     int pos = 0;
 
@@ -27,21 +34,20 @@ static void printf_unsigned(unsigned long long num, int radix){
         buffer[pos++] = g_HexChars[rem];
     } while(num > 0);
 
-    while(--pos >= 0) putc(buffer[pos]); // Note reverse order
+    while(--pos >= 0) out_fn(buffer[pos]); // Note reverse order
 }
 
-static void printf_signed(unsigned long long num, int radix){
+static void printf_signed(print_callable_fn_t out_fn, unsigned long long num, int radix){
     if(num < 0){
-        putc('-');
+        out_fn('-');
-        printf_unsigned(-num, radix);
+        printf_unsigned(out_fn, -num, radix);
     }
-    else printf_unsigned(num, radix);
+    else printf_unsigned(out_fn, num, radix);
 }
 
-void printf(char *fmt, ...){
+// printf() template
+static void _vprintf(print_callable_fn_t out_fn, char *fmt, va_list args){
     // Variadic function arguments
-    va_list args;
-    va_start(args, fmt);
 
     while(*fmt){
         if(*fmt == '%'){
@@ -52,10 +58,10 @@ void printf(char *fmt, ...){
             fmt++;
             switch(*fmt){
                 case '%':
-                    putc('%');
+                    out_fn('%');
                     break;
                 case 'c':
-                    putc((char)va_arg(args, int));
+                    out_fn((char)va_arg(args, int));
                     break;
                 case 's':
                     puts(va_arg(args, char *));
@@ -89,19 +95,39 @@ void printf(char *fmt, ...){
             // TODO: Implement length modifiers
             if(number){
                 if(sign){
-                    printf_signed(va_arg(args, int), radix);
+                    printf_signed(out_fn, va_arg(args, int), radix);
                 }
                 else{
-                    printf_unsigned(va_arg(args, unsigned int), radix);
+                    printf_unsigned(out_fn, va_arg(args, unsigned int), radix);
                 }
             }
 
             fmt++;
         }
-        else putc(*(fmt++));
+        else out_fn(*(fmt++));
     }
 }
 
+void vprintf(char *fmt, va_list args){
+    _vprintf(putc, fmt, args);
+}
+
+void printf(char *fmt, ...){
+    va_list args;
+    va_start(args, fmt);
+    _vprintf(putc, fmt, args);
+}
+
+void serial_vprintf(char *fmt, va_list args){
+    _vprintf(putc, fmt, args);
+}
+
+void serial_printf(char *fmt, ...){
+    va_list args;
+    va_start(args, fmt);
+    _vprintf(serial_putc, fmt, args);
+}
+
 void clear_screen(){
     vga_fill_screen(' ', VGA_COLOR_BG_BLACK | VGA_COLOR_FG_WHITE);
     vga_set_cursor(0);

src/kernel/main.c

@@ -3,7 +3,7 @@
 #include "hal/hal.h"
 #include "drivers/timer.h"
 #include "drivers/keyboard.h"
-#include "drivers/serial.h"
+#include "drivers/uart.h"
 #include "fs/vfs.h"
 #include "arch/i686/mm/pmm.h"
 #include "arch/i686/mm/vmm.h"
@@ -18,6 +18,9 @@ void __attribute__((cdecl)) kmain(multiboot_info_t *multiboot_info){
     // Initialize chip-specific hardware
     hal_initialize();
 
+    // Initialize serial
+    uart_initialize(COM1, 2);
+
     // Initialize physical memory manager
     uint32_t mem_size = 1024 + multiboot_info->mem_lower + multiboot_info->mem_upper*64;
 
@@ -25,7 +28,7 @@ void __attribute__((cdecl)) kmain(multiboot_info_t *multiboot_info){
 
     for(int i = 0; i < multiboot_info->mmap_length; i += sizeof(multiboot_memory_map_t)){
         multiboot_memory_map_t *memory_map = (multiboot_memory_map_t *)(multiboot_info->mmap_addr + i);
-        printf("Start Addr: 0x%x%x | Length: 0x%x%x | Size: 0x%x | Type: %i\n", memory_map->addr_h, memory_map->addr_l, memory_map->len_h, memory_map->len_l, memory_map->size, memory_map->type);
+        serial_printf("Start Addr: 0x%x%x | Length: 0x%x%x | Size: 0x%x | Type: %i\n", memory_map->addr_h, memory_map->addr_l, memory_map->len_h, memory_map->len_l, memory_map->size, memory_map->type);
     
         if(memory_map->type == 1){
             i686_pmm_init_region(memory_map->addr_l, memory_map->len_l);

src/kernel/shell.c

@@ -2,7 +2,7 @@
 #include "lib/stdio.h"
 #include "lib/string.h"
 #include "lib/memory.h"
-#include "drivers/serial.h"
+#include "drivers/uart.h"
 
 int shell_run(char *cmd){
     int ret = 0;
@@ -17,12 +17,22 @@ int shell_run(char *cmd){
     else if(!strcmp(cmd, "clear")){
         clear_screen();
     }
-    else if(!strcmp(cmd, "serial")){
+    else if(!strcmp(cmd, "uart")){
-        serial_write(COM1, 'H');
+        uart_write(COM1, '\x1b');
-        serial_write(COM1, 'E');
+        uart_write(COM1, '[');
-        serial_write(COM1, 'L');
+        uart_write(COM1, '3');
-        serial_write(COM1, 'L');
+        uart_write(COM1, '2');
-        serial_write(COM1, 'O');
+        uart_write(COM1, 'm');
+        uart_write(COM1, 'H');
+        uart_write(COM1, 'E');
+        uart_write(COM1, 'L');
+        uart_write(COM1, 'L');
+        uart_write(COM1, 'O');
+        uart_write(COM1, '\n');
+        uart_write(COM1, '\x1b');
+        uart_write(COM1, '[');
+        uart_write(COM1, '0');
+        uart_write(COM1, 'm');
     }
     else{
         printf("SHELL: Unknown command \"%s\"\n", cmd);