From 4047bc3936b91d0af0bae6685686b70087a02ff7 Mon Sep 17 00:00:00 2001
From: Gregory Bowne <gbowne144@gmail.com>
Date: Wed, 26 Nov 2025 16:02:07 -0800
Subject: [PATCH] Update display.c

Added the 95% completely wired up display driver implementation file
---
 kernel/display.c | 77 +++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 60 insertions(+), 17 deletions(-)

diff --git a/kernel/display.c b/kernel/display.c
index 3f8d14c..a22dc24 100644
--- a/kernel/display.c
+++ b/kernel/display.c
@@ -1,36 +1,79 @@
 #include "display.h"
-#include "io.h" // Include your I/O header for port access
+#include "io.h"
 #include "vga.h"
 
 // Initialize the display
 void init_display(void) {
-    // Initialize VGA settings, if necessary
-    // This could involve setting up the VGA mode, etc.
-    set_display_mode(0x13); // Example: Set to 320x200 256-color mode
+    // Initialize the VGA driver. This typically sets up the 80x25 text mode,
+    // clears the screen, and sets the cursor.
+    vga_init();
 }
 
 // Enumerate connected displays
 void enumerate_displays(void) {
-    // This is a simplified example. Actual enumeration may require
-    // reading from specific VGA registers or using BIOS interrupts.
+    // This function is often a complex operation in a real driver.
+    // In this simplified kernel/VGA text mode environment, we use printf
+    // to output a message and rely on the fact that VGA is present.
     
-    // For demonstration, we will just print a message
-    // In a real driver, you would check the VGA registers
-    // to determine connected displays.
-    clear_display();
-    // Here you would typically read from VGA registers to find connected displays
-    // For example, using inb() to read from VGA ports
+    // Clear the display before printing a message
+    vga_clear(vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK));
+    
+    // Output a simplified enumeration message
+    vga_printf("Display: Standard VGA Text Mode (80x25) Detected.\n");
+    
+    // In a real driver, you would use inb() and outb() with specific VGA ports
+    // to read information (e.g., from the CRTC registers 0x3D4/0x3D5)
+    // to check for display presence or configuration.
 }
 
 // Set the display mode
+// NOTE: Setting arbitrary VGA modes (like 0x13 for 320x200) is very complex
+// and requires writing hundreds of register values, often done via BIOS in
+// real mode. Since we are in protected mode and have a simple text driver,
+// this function is kept simple or treated as a placeholder for full mode changes.
 void set_display_mode(uint8_t mode) {
-    // Set the VGA mode by writing to the appropriate registers
-    outb(VGA_PORT, mode); // Example function to write to a port
+    // Check if the requested mode is a known mode (e.g., VGA Text Mode 3)
+    // For this example, we simply acknowledge the call.
+    // A true mode set would involve complex register sequencing.
+    
+    // The provided vga.c is a Text Mode driver, so a graphical mode set
+    // like 0x13 (320x200 256-color) would break the existing vga_printf functionality.
+    
+    // A simplified text-mode-specific response:
+    if (mode == 0x03) { // Mode 3 is standard 80x25 text mode
+        vga_printf("Display mode set to 80x25 Text Mode (Mode 0x03).\n");
+        vga_init(); // Re-initialize the text mode
+    } else {
+        // Simple I/O example based on the original structure (Caution: Incomplete for full mode set)
+        outb(VGA_PORT, mode); // Example function to write to a port
+        vga_printf("Attempting to set display mode to 0x%x. (Warning: May break current display)\n", mode);
+    }
 }
 
 // Clear the display
 void clear_display(void) {
-    // Clear the display by filling it with a color
-    // This is a placeholder for actual clearing logic
-    // You would typically write to video memory here
+    // Use the VGA driver's clear function, typically clearing to black on light grey
+    // or black on black. We'll use the black on light grey from vga_init for consistency.
+    vga_clear(vga_entry_color(VGA_COLOR_BLACK, VGA_COLOR_LIGHT_GREY));
+    // Reset cursor to 0, 0
+    vga_set_cursor_position(0, 0);
+}
+
+// Helper function to write a string
+void display_write_string(const char* str) {
+    // Use the VGA driver's string writing function
+    vga_write_string(str, my_strlen(str));
+}
+
+// Helper function to print a formatted string
+void display_printf(const char* format, ...) {
+    // Use the VGA driver's printf function
+    va_list args;
+    va_start(args, format);
+    
+    // The vga_printf function already handles the va_list internally,
+    // so we can just call it directly.
+    vga_printf(format, args);
+    
+    va_end(args);
 }