Implement date command

bootloader/bootloader.asm

@@ -64,7 +64,7 @@ rm_start:
     ; Loading the assembly kernel from floppy
 
     ASM_KERNEL_BASE equ 0x100   ; 0x0100:0x0 = 0x1000
-    sectors equ 0x28            ; sectors to read
+    sectors equ 0x30            ; sectors to read
     bootdev equ 0x0
 
     mov ax, ASM_KERNEL_BASE

fill.bash

@@ -1,5 +1,5 @@
 #!/bin/bash
 
 size=`stat -c%s kernel.bin`
-let filler_size=4096-$size
+let filler_size=8192-$size
 dd if=/dev/zero of=filler.bin bs=1 count=$filler_size

kernel/src/console.cpp

@@ -70,7 +70,7 @@ void k_print(std::size_t number){
 
     --i;
 
-    for(; i > 0; --i){
+    for(; i >= 0; --i){
         k_print(buffer[i]);
     }
 }

kernel/src/shell.cpp

@@ -16,6 +16,20 @@ void reboot_command();
 void help_command();
 void uptime_command();
 void clear_command();
+void date_command();
+
+struct command_definition {
+    const char* name;
+    void (*function)();
+};
+
+std::array<command_definition, 5> commands = {{
+    {"reboot", reboot_command},
+    {"help", help_command},
+    {"uptime", uptime_command},
+    {"clear", clear_command},
+    {"date", date_command}
+}};
 
 std::size_t current_input_length = 0;
 char current_input[50];
@@ -64,18 +78,6 @@ bool str_equals(const char* a, const char* b){
     return *a == *b;
 }
 
-struct command_definition {
-    const char* name;
-    void (*function)();
-};
-
-std::array<command_definition, 4> commands = {{
-    {"reboot", reboot_command},
-    {"help", help_command},
-    {"uptime", uptime_command},
-    {"clear", clear_command}
-}};
-
 void reboot_command(){
     interrupt<60>();
 }
@@ -113,6 +115,126 @@ void clear_command(){
     wipeout();
 }
 
+#define CURRENT_YEAR        2013
+#define century_register    0x00
+#define cmos_address        0x70
+#define cmos_data           0x71
+
+int get_update_in_progress_flag() {
+      out_byte(cmos_address, 0x0A);
+      return (in_byte(cmos_data) & 0x80);
+}
+
+uint8_t get_RTC_register(int reg) {
+      out_byte(cmos_address, reg);
+      return in_byte(cmos_data);
+}
+
+void date_command(){
+    uint8_t second;
+    uint8_t minute;
+    uint8_t hour;
+    uint8_t day;
+    uint8_t month;
+    unsigned int year;
+
+    uint8_t century;
+    uint8_t last_second;
+    uint8_t last_minute;
+    uint8_t last_hour;
+    uint8_t last_day;
+    uint8_t last_month;
+    uint8_t last_year;
+    uint8_t last_century;
+    uint8_t registerB;
+
+    while (get_update_in_progress_flag()){};                // Make sure an update isn't in progress
+
+    second = get_RTC_register(0x00);
+    minute = get_RTC_register(0x02);
+    hour = get_RTC_register(0x04);
+    day = get_RTC_register(0x07);
+    month = get_RTC_register(0x08);
+    year = get_RTC_register(0x09);
+
+    if(century_register != 0) {
+        century = get_RTC_register(century_register);
+    }
+
+    do {
+        last_second = second;
+        last_minute = minute;
+        last_hour = hour;
+        last_day = day;
+        last_month = month;
+        last_year = year;
+        last_century = century;
+
+        while (get_update_in_progress_flag()){};           // Make sure an update isn't in progress
+
+        second = get_RTC_register(0x00);
+        minute = get_RTC_register(0x02);
+        hour = get_RTC_register(0x04);
+        day = get_RTC_register(0x07);
+        month = get_RTC_register(0x08);
+        year = get_RTC_register(0x09);
+
+        if(century_register != 0) {
+            century = get_RTC_register(century_register);
+        }
+    } while( (last_second != second) || (last_minute != minute) || (last_hour != hour) ||
+        (last_day != day) || (last_month != month) || (last_year != year) ||
+        (last_century != century) );
+
+    registerB = get_RTC_register(0x0B);
+
+    // Convert BCD to binary values if necessary
+
+    if (!(registerB & 0x04)) {
+        second = (second & 0x0F) + ((second / 16) * 10);
+        minute = (minute & 0x0F) + ((minute / 16) * 10);
+        hour = ( (hour & 0x0F) + (((hour & 0x70) / 16) * 10) ) | (hour & 0x80);
+        day = (day & 0x0F) + ((day / 16) * 10);
+        month = (month & 0x0F) + ((month / 16) * 10);
+        year = (year & 0x0F) + ((year / 16) * 10);
+
+        if(century_register != 0) {
+            century = (century & 0x0F) + ((century / 16) * 10);
+        }
+    }
+
+    // Convert 12 hour clock to 24 hour clock if necessary
+
+    if (!(registerB & 0x02) && (hour & 0x80)) {
+        hour = ((hour & 0x7F) + 12) % 24;
+    }
+
+    // Calculate the full (4-digit) year
+
+    if(century_register != 0) {
+        year += century * 100;
+    } else {
+        year += (CURRENT_YEAR / 100) * 100;
+        if(year < CURRENT_YEAR) year += 100;
+    }
+
+    k_print((std::size_t) day);
+    k_print('.');
+    k_print((std::size_t) month);
+    k_print('.');
+    k_print((std::size_t) year);
+
+    k_print(' ');
+
+    k_print((std::size_t) hour);
+    k_print(':');
+    k_print((std::size_t) minute);
+    k_print(':');
+    k_print((std::size_t) second);
+
+    k_print_line();
+}
+
 } //end of anonymous namespace
 
 void init_shell(){

kernel/src/timer.cpp

@@ -4,8 +4,8 @@
 
 namespace {
 
-std::size_t _timer_ticks;
-std::size_t _timer_seconds;
+std::size_t _timer_ticks = 0;
+std::size_t _timer_seconds = 0;
 
 void timer_handler(){
     ++_timer_ticks;