Implemented a simple status bar.

Author: KlausAschenbrenner

.vscode/settings.json

@@ -4,6 +4,7 @@
         "idt.h": "c",
         "screen.h": "c",
         "irq.h": "c",
-        "keyboard.h": "c"
+        "keyboard.h": "c",
+        "date.h": "c"
     }
 }

main64/kernel/common.c

@@ -120,6 +120,25 @@ int strcmp(char *s1, char *s2)
     return *(unsigned char *)s1 - *(unsigned char *)s2;
 }
 
+// A simple strcat implementation
+char *strcat(char *destination, char *source)
+{
+    // "ptr" points to the end of the destination string
+    char *ptr = destination + strlen(destination);
+ 
+    // Add the source characters to the destination string
+    while (*source != '\0')
+    {
+        *ptr++ = *source++;
+    }
+ 
+    // Null terminate the destination string
+    *ptr = '\0';
+ 
+    // Return the final string
+    return destination;
+}
+
 // Returns a substring from a given string
 int substring(char *source, int from, int n, char *target)
 {
@@ -290,4 +309,23 @@ int atoi(char *str)
     }
 
     return res;
+}
+
+// Formats an Integer value with a leading zero.
+void FormatInteger(int Value, char *Buffer)
+{
+    char str[32] = "";
+
+    // Empty the buffer
+    strcpy(Buffer, "");
+
+    // Add a leading zero - if necessary
+    if (Value < 10)
+    {
+        strcat(Buffer, "0");
+    }
+
+    // Add the integer value
+    itoa(Value, 10, str);
+    strcat(Buffer, str);
 }

main64/kernel/common.h

@@ -48,6 +48,9 @@ char *strcpy(char *destination, const char *source);
 // A simple strcmp implementation
 int strcmp(char *s1, char *s2);
 
+// A simple strcat implementation
+char *strcat(char *destination, char *source);
+
 // Returns a substring from a given string
 int substring(char *source, int from, int n, char *target);
 
@@ -78,4 +81,7 @@ static void ltoa_helper(unsigned long i, unsigned base, char *buf);
 // Converts an ASCII string to its integer value
 int atoi(char *str);
 
+// Formats an Integer value with a leading zero.
+void FormatInteger(int Value, char *Buffer);
+
 #endif

main64/kernel/date.c

@@ -0,0 +1,82 @@
+#include "common.h"
+#include "date.h"
+
+// The number of days for each month
+int NumberOfDaysPerMonth[12] =
+{
+    31, // January
+    28, // February
+    31, // March
+    30, // April
+    31, // Mai
+    30, // June
+    31, // July
+    31, // August
+    30, // September
+    31, // October
+    30, // November
+    31  // December
+};
+
+// Increments the system data by 1 second.
+void IncrementSystemDate()
+{
+    // Getting a reference to the BIOS Information Block
+    BiosInformationBlock *bib = (BiosInformationBlock *)BIB_OFFSET;
+
+    // Increment the system date by 1 second
+    bib->Second++;
+
+    // Roll over to the next minute
+    if (bib->Second > 59)
+    {
+        bib->Second = 0;
+        bib->Minute++;
+    }
+
+    // Roll over to the next hour
+    if (bib->Minute > 59)
+    {
+        bib->Minute = 0;
+        bib->Hour++;
+    }
+
+    // Roll over to the next day
+    if (bib->Hour > 23)
+    {
+        bib->Hour = 0;
+        bib->Day++;
+    }
+
+    // Roll over to the next month
+    // We don't check here for the leap year!!!
+    if (bib->Day > NumberOfDaysPerMonth[bib->Month - 1])
+    {
+        bib->Day = 1;
+        bib->Month++;
+    }
+}
+
+// Sets the system date.
+void SetDate(int Year, int Month, int Day)
+{
+    // Getting a reference to the BIOS Information Block
+    BiosInformationBlock *bib = (BiosInformationBlock *)BIB_OFFSET;
+
+    // Set the date
+    bib->Year = Year;
+    bib->Month = Month;
+    bib->Day = Day;
+}
+
+// Sets the system time.
+void SetTime(int Hour, int Minute, int Second)
+{
+    // Getting a reference to the BIOS Information Block
+    BiosInformationBlock *bib = (BiosInformationBlock *)BIB_OFFSET;
+
+    // Set the time
+    bib->Hour = Hour;
+    bib->Minute = Minute;
+    bib->Second = Second;
+}

main64/kernel/date.h

@@ -0,0 +1,13 @@
+#ifndef DATE_H
+#define DATE_H
+
+// Increments the system data by 1 second.
+void IncrementSystemDate();
+
+// Sets the system date.
+void SetDate(int Year, int Month, int Day);
+
+// Sets the system time.
+void SetTime(int Hour, int Minute, int Second);
+
+#endif

main64/kernel/drivers/keyboard.c

@@ -44,7 +44,7 @@ void scanf(char *buffer, int buffer_size)
         // When we have hit the ENTER key, we have finished entering our input data
         if (key == KEY_RETURN)
         {
-            print_char('\n', 1);
+            print_char('\n');
             break;
         }
 
@@ -66,7 +66,7 @@ void scanf(char *buffer, int buffer_size)
                 // Clear out the last printed key
                 // This also moves the cursor one character forward, so we have to go back
                 // again with the cursor in the next step
-                print_char(' ', 1);
+                print_char(' ');
 
                 // Move the cursor position one character back again
                 GetCursorPosition(&row, &col);
@@ -84,7 +84,7 @@ void scanf(char *buffer, int buffer_size)
             // If we have pressed a non-printable key, the character is not printed out
             if (key != 0)
             {
-                print_char(key, 1);
+                print_char(key);
             }
 
             // Write the entered character into the provided buffer

main64/kernel/drivers/screen.c

@@ -4,9 +4,21 @@
 // Define a variable for the screen location information
 ScreenLocation screenLocation;
 
+// The number of rows of the video memory
+int NumberOfRows;
+
+// The number of columns of the video memory
+int NumberOfColumns;
+
+// The blank character
+unsigned char BLANK = 0x20;
+
 // Initializes the screen
-void InitializeScreen()
+void InitializeScreen(int Cols, int Rows)
 {
+    NumberOfColumns = Cols;
+    NumberOfRows = Rows;
+
     screenLocation.Row = 1;
     screenLocation.Col = 1;
     screenLocation.Attributes = COLOR_WHITE;
@@ -41,7 +53,7 @@ void SetCursorPosition(int Row, int Col)
 void MoveCursor()
 {
    // Calculate the linear offset of the cursor
-   short cursorLocation = (screenLocation.Row - 1) * COLS + (screenLocation.Col - 1);
+   short cursorLocation = (screenLocation.Row - 1) * NumberOfColumns + (screenLocation.Col - 1);
 
    // Setting the cursor's high byte
    outb(0x3D4, 14);
@@ -58,12 +70,12 @@ void ClearScreen()
     char *video_memory = (char *)VIDEO_MEMORY;
     int row, col;
 
-    for (row = 0; row < ROWS; row++)
+    for (row = 0; row < NumberOfRows; row++)
     {
-        for (col = 0; col < COLS; col++)
+        for (col = 0; col < NumberOfColumns; col++)
         {
-            int offset = row * COLS * 2 + col * 2;
-            video_memory[offset] = 0x20; // Blank
+            int offset = row * NumberOfColumns * 2 + col * 2;
+            video_memory[offset] = BLANK;
             video_memory[offset + 1] = screenLocation.Attributes;
         }
     }
@@ -74,40 +86,30 @@ void ClearScreen()
     MoveCursor();
 }
 
-int SetScreenRow(int Row)
-{
-    int currentRow = screenLocation.Row;
-    screenLocation.Row = Row;
-    screenLocation.Col = 1;
-
-    return currentRow;
-}
-
 // Scrolls the screen, when we have used more than 25 rows
 void Scroll()
 {
-   // Get a space character with the default colour attributes.
-   unsigned char attributeByte = (0 /*black*/ << 4) | (15 /*white*/ & 0x0F);
-   unsigned short blank = 0x20 /* space */ | (attributeByte << 8);
-   char* video_memory = (char *)VIDEO_MEMORY;
+   unsigned char attributeByte = (COLOR_BLACK << 4) | (COLOR_WHITE & 0x0F);
+   char *video_memory = (char *)VIDEO_MEMORY;
+   int i;
 
-   // Row 25 is the end, this means we need to scroll up
-   if (screenLocation.Row > ROWS)
+   // Check if we have reached the last row of the screen.
+   // This means we need to scroll up
+   if (screenLocation.Row > NumberOfRows)
    {
-       int i;
-       for (i = 0; i < COLS * 2 * (ROWS - 1); i++)
+       for (i = 0; i < NumberOfColumns * 2 * (NumberOfRows - 1); i++)
        {
-           video_memory[i] = video_memory[i + (COLS * 2)];
+           video_memory[i] = video_memory[i + (NumberOfColumns * 2)];
        }
 
        // Blank the last line
-       for (i = (ROWS - 1) * COLS * 2; i < ROWS * COLS * 2; i += 2)
+       for (i = (NumberOfRows - 1) * NumberOfColumns * 2; i < NumberOfRows * NumberOfColumns * 2; i += 2)
        {
-           video_memory[i] = blank;
+           video_memory[i] = BLANK;
            video_memory[i + 1] = attributeByte;
        }
 
-       screenLocation.Row = ROWS;
+       screenLocation.Row = NumberOfRows;
    }
 }
 
@@ -116,26 +118,33 @@ void printf(char *string)
 {
     while (*string != '\0')
     {
-        print_char(*string, 1);
+        print_char(*string);
         string++;
     }
 }
 
-// Prints out a null-terminated string, without scrolling
-// the terminal window.
-void printf_noscrolling(char *string)
+// Prints out the status line string
+void PrintStatusLine(char *string)
 {
+    unsigned char color = (COLOR_GREEN << 4) | (COLOR_BLACK & 0x0F);
+    char *video_memory = (char *)VIDEO_MEMORY;
+    int colStatusLine = 1;
+
     while (*string != '\0')
     {
-        print_char(*string, 0);
+        int offset = (25 - 1) * NumberOfColumns * 2 + (colStatusLine - 1) * 2;
+        video_memory[offset] = *string;
+        video_memory[offset + 1] = color;
+        colStatusLine++;
+
         string++;
     }
 }
 
 // Prints a single character on the screen
-void print_char(char character, int scrolling)
+void print_char(char character)
 {
-    char* video_memory = (char *)VIDEO_MEMORY;
+    char *video_memory = (char *)VIDEO_MEMORY;
 
     switch(character)
     {
@@ -155,7 +164,7 @@ void print_char(char character, int scrolling)
         }
         default:
         {
-            int offset = (screenLocation.Row - 1) * COLS * 2 + (screenLocation.Col - 1) * 2;
+            int offset = (screenLocation.Row - 1) * NumberOfColumns * 2 + (screenLocation.Col - 1) * 2;
             video_memory[offset] = character;
             video_memory[offset + 1] = screenLocation.Attributes;
             screenLocation.Col++;
@@ -164,11 +173,8 @@ void print_char(char character, int scrolling)
         }
     }
 
-    if (scrolling)
-    {
-        Scroll();
-        MoveCursor();
-    }
+    Scroll();
+    MoveCursor();
 }
 
 // Prints out an integer value