shift done, backspace done

bootmain.c

@@ -27,7 +27,7 @@ bootmain(void)
   void (*entry)(void);
   uchar* pa;
 
-  elf = (Elf32_Ehdr*)0x10000;  // scratch space
+  elf = (Elf32_Ehdr*)0x20000;  // scratch space
 
   // Read 1st page off disk
   readseg((uchar*)elf, 4096, 0);

cpu/memlayout.h

@@ -2,7 +2,7 @@
 
 #define KERNBASE 0x80000000
 #define PGSIZE   0x1000
-#define PHYSTOP  0x8000000
+#define PHYSTOP  0x8000000   // 128 Mib
 
 #define PGROUNDUP(sz)  (((sz)+PGSIZE-1) & ~(PGSIZE-1))
 #define PGROUNDDOWN(a) (((a)) & ~((uintptr_t)(PGSIZE-1)))

drivers/keyboard.c

@@ -42,3 +42,7 @@ uint8_t kbd_take_from_copy_buffer() {
 bool kbd_can_take_from_copy_buffer() {
     return kbd_state_shrd.copy_len > 0;
 }
+bool kbd_is_pressed(uint8_t code) {
+    check(code < 128);
+    return kbd_state_shrd.copy_pressed[code >> 3] & (1u << (code & 0x7));
+}

drivers/keyboard.h

@@ -16,6 +16,7 @@ typedef struct {
 
 #define KEYCODE_SHIFT 42
 #define KEYCODE_ENTER 28
+#define KEYCODE_BACKSPACE 14
 
 /* decoding */
 static const char keysym_mapped_ascii_lower[] = {
@@ -41,3 +42,4 @@ void init_keyboard();
 
 uint8_t kbd_take_from_copy_buffer();
 bool kbd_can_take_from_copy_buffer();
+bool kbd_is_pressed(uint8_t code);

drivers/vga.c

@@ -1,3 +1,4 @@
+#include "vga.h"
 #include "port.h"
 #include "../lib/string.h"
 #include "cpu/memlayout.h"
@@ -27,22 +28,12 @@ static unsigned char get_color(unsigned char fg, unsigned char bg) {
     return (bg << 4) + fg;
 }
 
-enum {
+unsigned vga_get_offset(unsigned col, unsigned row) {
-    ROWS = 25,
+    return row * VGA_COLS + col;
-    COLS = 80,
-
-    VGA_CTRL_REGISTER = 0x3d4,
-    VGA_DATA_REGISTER = 0x3d5,
-    VGA_OFFSET_LOW = 0x0f,
-    VGA_OFFSET_HIGH = 0x0e,
-};
-
-static unsigned get_offset(unsigned col, unsigned row) {
-    return row * COLS + col;
 }
 
-static unsigned get_row_from_offset(unsigned offset) {
+unsigned vga_get_row_from_offset(unsigned offset) {
-    return offset / COLS;
+    return offset / VGA_COLS;
 }
 
 void vga_set_cursor(unsigned offset) {
@@ -66,31 +57,31 @@ void vga_set_char(unsigned offset, char c) {
 }
 
 void vga_clear_screen() {
-    for (unsigned i = 0; i < ROWS * COLS; ++i) {
+    for (unsigned i = 0; i < VGA_ROWS * VGA_COLS; ++i) {
         vga_set_char(i, ' ');
     }
     vga_set_cursor(0);
 }
 
 static unsigned scroll() {
-    kmemmove(video_memory, video_memory + 2 * COLS, 2 * COLS * (ROWS-1));
+    kmemmove(video_memory, video_memory + 2 * VGA_COLS, 2 * VGA_COLS * (VGA_ROWS-1));
-    for (int col = 0; col < COLS; col++) {
+    for (int col = 0; col < VGA_COLS; col++) {
-        vga_set_char(get_offset(col, ROWS - 1), ' ');
+        vga_set_char(vga_get_offset(col, VGA_ROWS - 1), ' ');
     }
-    return get_offset(0, ROWS - 1);
+    return vga_get_offset(0, VGA_ROWS - 1);
 }
 
 void vga_print_string(const char* s) {
     unsigned offset = vga_get_cursor();
     while (*s != 0) {
         if (*s == '\n') {
-            offset = get_offset(0, get_row_from_offset(offset) + 1);
+            offset = vga_get_offset(0, vga_get_row_from_offset(offset) + 1);
         } else {
             vga_set_char(offset, *s);
             offset++;
         }
         s++;
-        if (offset >= COLS * ROWS) {
+        if (offset >= VGA_COLS * VGA_ROWS) {
             offset = scroll();
         }
     }

drivers/vga.h

@@ -1,7 +1,26 @@
 #pragma once
 
-void vga_clear_screen();
+#include <stdint.h>
 
+enum {
+  VGA_ROWS = 25,
+  VGA_COLS = 80,
+
+  VGA_CTRL_REGISTER = 0x3d4,
+  VGA_DATA_REGISTER = 0x3d5,
+  VGA_OFFSET_LOW = 0x0f,
+  VGA_OFFSET_HIGH = 0x0e,
+};
+
+
+
+unsigned vga_get_cursor();
+unsigned vga_get_row_from_offset(unsigned offset);
+unsigned vga_get_offset(unsigned col, unsigned row);
+void vga_set_cursor(unsigned offset);
+
+void vga_clear_screen();
+void vga_set_char(unsigned offset, char c);
 void vga_print_string(const char* s);
 
 void vgaMode13();

kernel.c

@@ -36,14 +36,24 @@ void read_line_input(char* buf, size_t* ret_len, size_t cap) {
         while (kbd_can_take_from_copy_buffer()) {
             uint8_t keycode = kbd_take_from_copy_buffer();
 
-            bool shift_pressed = kbd_state_shrd.copy_pressed[42 >> 3] & (42 & 0x7);
+            bool shift_pressed = kbd_is_pressed(KEYCODE_SHIFT);
             const size_t keycodes = sizeof(keysym_mapped_ascii_upper);
             check(keycodes == sizeof(keysym_mapped_ascii_lower));
 
             if (keycode == KEYCODE_ENTER) {
                 goto end;
-            }
+            } else if (keycode == KEYCODE_BACKSPACE) {
-            if (keycode < keycodes && keycode) {
+                unsigned scr_offset = vga_get_cursor();
+                if (len > 0 && scr_offset > 0) {
+                    // if (scr_offset % VGA_COLS) {
+                    //     vga_set
+                    // }
+                    // vga_set_char()
+                    vga_set_char(scr_offset - 1, ' ');
+                    vga_set_cursor(scr_offset - 1);
+                    len--;
+                }
+            } else if (keycode < keycodes) {
                 char ch = shift_pressed ? keysym_mapped_ascii_upper[keycode] :
                     keysym_mapped_ascii_lower[keycode];
                 if (ch != 0) {
@@ -61,8 +71,6 @@ void read_line_input(char* buf, size_t* ret_len, size_t cap) {
         asm("hlt");
         size_t count = kbd_state_shrd.len;
         if (count > 0) {
-            // char haha[2] = {count+'0', 0};
-            // printk(haha);
             cli();
             size_t rem = KEYBOARD_INTERRUPT_BUF_CAP - kbd_state_shrd.copy_len;
             size_t copying = rem < count ? rem : count;
@@ -79,9 +87,9 @@ void read_line_input(char* buf, size_t* ret_len, size_t cap) {
 
 
 void kmain() {
-    freerange(P2V(1u<<20), P2V(2u<<20)); // 1MB - 2MB
+    freerange(P2V(2u<<20), P2V(3u<<20));
     kvmalloc();  // map all of physical memory at KERNBASE
-    freerange(P2V(2u<<20), P2V(PHYSTOP));
+    freerange(P2V(3u<<20), P2V(PHYSTOP));
 
     load_gdt();
     init_keyboard();
@@ -116,7 +124,6 @@ void kmain() {
             const char* cmd = input + 4;
             run_elf(cmd);
         } else {
-            printk("as\n");
             printk("unknown command, try: halt | run CMD\n");
         }
     }