From 5b16da23ed96b7522803d40bf27b7a87bb9dcf97 Mon Sep 17 00:00:00 2001
From: churl <tobi@urpost.de>
Date: Mon, 9 May 2022 14:02:44 +0200
Subject: [PATCH] simplify cga memory manipulation

---
 c_os/devices/CGA.cc | 25 ++++++++-----------------
 c_os/devices/CGA.h  | 19 ++++++++++++++++---
 c_os/main.cc        | 22 ++++++++++++++++++++++
 3 files changed, 46 insertions(+), 20 deletions(-)

diff --git a/c_os/devices/CGA.cc b/c_os/devices/CGA.cc
index 84bc33b..6e6a905 100755
--- a/c_os/devices/CGA.cc
+++ b/c_os/devices/CGA.cc
@@ -73,14 +73,14 @@ void CGA::show(int x, int y, char character, unsigned char attrib) {
 
     /* Hier muess Code eingefuegt werden */
 
-    if (x > COLUMNS || y > ROWS) {
+    if (x >= COLUMNS || y >= ROWS) {
         // Out of bounds
         return;
     }
 
-    char* pos = (char*)(CGA_START + 2 * (x + y * COLUMNS));  // cast to char* to make writable
-    *pos = character;
-    *(pos + 1) = attrib;
+    cga_char_t* pos = (cga_char_t*)(CGA_START + 2 * (x + y * COLUMNS));  // cast to char* to make writable
+    pos->cga_char = character;
+    pos->cga_attribute = attrib;
 }
 
 /*****************************************************************************
@@ -147,19 +147,13 @@ void CGA::print(char* string, int n, unsigned char attrib) {
  *****************************************************************************/
 void CGA::scrollup() {
 
-    /* Hier muess Code eingefuegt werden */
-
-    // TODO: I really want a scrollback buffer
+    /* Hier muss Code eingefuegt werden */
 
     // Move up
-    for (unsigned short byte = 2 * COLUMNS * 1; byte < 2 * COLUMNS * ROWS; ++byte) {
-        *((char*)(CGA_START + byte - 2 * COLUMNS * 1)) = *(CGA_START + byte);
-    }
+    mymemcpy<cga_line_t>((cga_line_t*)CGA_START, (cga_line_t*)CGA_START + 1, ROWS - 1);
 
     // Clear last line
-    for (unsigned short byte = 2 * COLUMNS * (ROWS - 1); byte < 2 * COLUMNS * ROWS; ++byte) {
-        *((char*)(CGA_START + byte)) = '\0';
-    }
+    myzero<cga_line_t>((cga_line_t*)CGA_START + ROWS - 1);
 }
 
 /*****************************************************************************
@@ -171,10 +165,7 @@ void CGA::clear() {
 
     /* Hier muess Code eingefuegt werden */
 
-    for (unsigned short byte = 2 * COLUMNS * 0; byte < 2 * COLUMNS * ROWS; ++byte) {
-        *((char*)(CGA_START + byte)) = '\0';
-    }
-
+    myzero<cga_page_t>((cga_page_t*)CGA_START);
     this->setpos(0, 0);
 }
 
diff --git a/c_os/devices/CGA.h b/c_os/devices/CGA.h
index 0ff9d7b..c9e9129 100755
--- a/c_os/devices/CGA.h
+++ b/c_os/devices/CGA.h
@@ -15,6 +15,7 @@
 #define __CGA_include__
 
 #include "kernel/IOport.h"
+#include "lib/MyStdLib.h"
 
 class CGA {
 
@@ -63,6 +64,18 @@ public:
     enum { ROWS = 25,
            COLUMNS = 80 };
 
+    // NOTE: I added this
+    typedef struct {
+        char cga_char;
+        char cga_attribute;
+    } cga_char_t;
+    typedef struct {
+        cga_char_t cga_line[COLUMNS];
+    } cga_line_t;
+    typedef struct {
+        cga_line_t cga_page[ROWS];
+    } cga_page_t;
+
     // Setzen des Cursors in Spalte x und Zeile y.
     void setpos(int x, int y);
 
@@ -73,14 +86,14 @@ public:
     void show(int x, int y, char character, unsigned char attrib = STD_ATTR);
 
     // Anzeige mehrerer Zeichen ab der aktuellen Cursorposition
-    void print(char* string, int n, unsigned char attrib = STD_ATTR);
+    virtual void print(char* string, int n, unsigned char attrib = STD_ATTR);
 
     // Verschiebt den Bildschirminhalt um eine Zeile nach oben.
     // Neue Zeile am unteren Bildrand mit Leerzeichen fuellen
-    void scrollup();
+    virtual void scrollup();
 
     // Lösche den Textbildschirm
-    void clear();
+    virtual void clear();
 
     // Hilfsfunktion zur Erzeugung eines Attribut-Bytes
     unsigned char attribute(CGA::color bg, CGA::color fg, bool blink);
diff --git a/c_os/main.cc b/c_os/main.cc
index 80d1d25..9229c76 100755
--- a/c_os/main.cc
+++ b/c_os/main.cc
@@ -14,17 +14,39 @@
 #include "kernel/Globals.h"
 #include "user/HeapDemo.h"
 
+// TODO: Where to put this?
+void scroll_mode() {
+    Key key;
+    // while (true) {
+    //     key = kb.key_hit();
+
+    //     switch (key.ascii()) {
+    //     case 'k':
+    //         kout.pageup();
+    //     case 'j':
+    //         kout.pagedown();
+    //     }
+    // }
+}
+
 int main() {
     kout.clear();
 
     // Speicherverwaltung initialisieren
     allocator.init();
 
+    // Initialize scrollback buffer
+    // kout.init();
+
+    allocator.dump_free_memory();
+
     // text_demo();
     // sound_demo();
     // keyboard_demo();
     heap_demo();
 
+    // scroll_mode();
+
     while (1) {};
     return 0;
 }