Move to own ISR solution rather than using GCC ISRs. Lots of changes to accomodate that.

.gitignore

@@ -4,4 +4,5 @@
 *.sector
 *.o
 img.d/
-build/
+build/
+isr.S

src/hello/hello.c

@@ -5,6 +5,7 @@ int main() {
   uint32_t PID = getPID();
   char intbuffer[32];
   uint32_t index = int_to_decimal(PID, intbuffer);
+  uint32_t x = *(uint32_t*)0xdeadbeef;
   while (1) {
     counter++;
     if (counter == 312500) {

src/hello/hello.ld

@@ -1,14 +1,14 @@
 OUTPUT_FORMAT(binary)
 OUTPUT_ARCH(i386:i386)
 
-OUTPUT(build/program/hello.bin)
+OUTPUT(build/hello/hello.bin)
 
 SECTIONS {
   . = 0x8020;
 
   .text : {
     build/program_code_entry.o(.text)
-    build/program/hello.o(.text)
+    build/hello/hello.o(.text)
     build/common/common.o(.text)
   }
 }

src/kernel/gen_isr_asm.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env zsh
+
+test -f isr.S && rm isr.S
+cp isr.S.base isr.S
+
+for i ({0..255}); do 
+  cat  >> isr.S << EOF
+isr$i:
+  push ebp
+  mov ebp, esp
+  push $i
+  jmp catchall
+EOF
+done
+
+x=""
+for i ({0..255}); do 
+  if [ $i = 255 ]; then 
+    x="$x isr$i"
+  else
+    x="$x isr$i,"
+  fi
+done
+
+echo "isrs dd $x" >> isr.S

src/kernel/global.cpp

@@ -5,6 +5,7 @@ namespace Global {
   Kernel* kernel = 0;
   Process* currentProc = 0;
   tss_struct* tss = 0;
+  bool currentProcValid = true;
 }
 
 void* operator new (uint32_t size) {

src/kernel/global.h

@@ -13,6 +13,7 @@ namespace Global {
   extern Kernel* kernel;
   extern Process* currentProc;
   extern tss_struct* tss;
+  extern bool currentProcValid;
 }
 
 void* operator new (uint32_t size);

src/kernel/idt.cpp

@@ -2,7 +2,11 @@
 
 GateEntry idt[256];
 
-void set_entry(uint8_t interrupt_number, uint16_t code_segment, void* handler, uint8_t type, uint8_t privilege) {
+void(*gates[256])(frame_struct*);
+
+extern void(*isrs[256])(void);
+
+void set_entry(uint8_t interrupt_number, uint16_t code_segment, void(*handler)(), uint8_t type, uint8_t privilege) {
   uint32_t handler_addr = (uint32_t)handler;
   uint16_t* handler_halves = (uint16_t*)&handler_addr;
   idt[interrupt_number] = (GateEntry) {
@@ -17,28 +21,41 @@ void set_entry(uint8_t interrupt_number, uint16_t code_segment, void* handler, u
   };
 }
 
-__attribute__((interrupt)) void interrupt_20(interrupt_frame* frame) {
-//  printf("Interrupt 20 received!!\n");
-  outb(0x20, 0x20);
-}
-
-__attribute__((interrupt)) void page_fault(interrupt_frame* frame, uint32_t err_code) {
+void page_fault(frame_struct* frame, uint32_t err_code) {
   uint32_t problem_address;
   asm("mov %%cr2, %0" : "=a" (problem_address) :);
-  printf("(EIP %x): Page Fault at %x\n", frame->eip, problem_address);
-  while (1) asm("hlt");
+  Global::kernel->terminal->printf("(EIP %x): Page Fault at %x\n", frame->eip, problem_address);
+  if (frame->cs & 3 == 0) {
+    Global::kernel->terminal->printf("[FATAL] Kernel Page Fault!!!\n");
+    while (1) asm("hlt");
+  } else {
+    // Print an error message.
+    Global::kernel->terminal->printf("PID %d Terminated due to page fault!\n", Global::currentProc->PID);
+    // We are currently in the kernel stack for the current process so we need to load the main kernel stack in to esp.
+    //Global::kernel->loadPrimaryStack();
+
+    asm volatile ("mov %0, %%esp" ::"m"(Global::kernel->stack));
+
+    // We can now safely delete the current process
+    Global::kernel->destroyProcess(Global::currentProc);
+
+    // We want to load the kernel's page directory too.
+    //Global::kernel->PD->select();
+
+    //Global::currentProcValid = false;
+    asm ("int $0x20"); // Call context switch.
+    while (1) asm("hlt");
+  }
 }
 
-__attribute__((interrupt)) void ignore_interrupt(interrupt_frame* frame) {
-  outb(0x20, 0x20);
-}
+void ignore_interrupt(frame_struct* frame) {}
 
-__attribute__((interrupt)) void gpf(interrupt_frame* frame, uint32_t err_code) {
+void gpf(frame_struct* frame, uint32_t err_code) {
   printf("General Protection Fault %x\n", err_code);
   while (1) asm("hlt");
 }
 
-__attribute__((interrupt)) void context_switch(interrupt_frame* frame) {
+void context_switch(frame_struct* frame) {
   // When any interrupt occurs (including context_switch), SS:ESP is set to
   // the values of SS0:ESP0 in Global::tss
   //
@@ -53,80 +70,86 @@ __attribute__((interrupt)) void context_switch(interrupt_frame* frame) {
   // to iret
 
   asm ("cli"); // Disable interrupts whilst handling the context switch.
-  asm ("pusha"); // Push registers to the stack
-  //asm ("pushf"); // Push flags to the stack
 
-  Process* currentProc = Global::currentProc;
+  // Restore eax
+  asm ("mov %0, %%eax"::"r"(frame->eax));
+
+  Process* currentProc = 0;
   Process* nextProc = 0;
 
-  // Write current esp to currentProc->kernelStackPtr
-  asm ("mov %%esp, %0" : "=a" (currentProc->kernelStackPtr):);
+  if (Global::currentProcValid) {
+    currentProc = Global::currentProc;
+    // Write current esp to currentProc->kernelStackPtr
+    asm ("mov %%esp, %0" : "=a" (currentProc->kernelStackPtr):);
+  }
 
-  if (currentProc) {
+  if (currentProc || !Global::currentProcValid) {
     xnoe::linkedlist<Process*>* processes = &Global::kernel->processes;
     
     // This cursed bit of code first determines if the processes list is longer than 1 and if it is
     // - Determines if it has 2 or more elements
     //   - If it has two, swap the first and last, update prev and next of each to be null or the other item
     //   - If it has more than two, add the start to the end then set start to the second element
-    if (processes->start->next != 0) {
-      if (processes->end->prev == processes->start) {
-        xnoe::linkedlistelem<Process*>* tmp = processes->start;
-        processes->start = processes->end;
-        processes->end = tmp;
+    if (processes->start) {
+      if (processes->start->next != 0) {
+        if (processes->end->prev == processes->start) {
+          xnoe::linkedlistelem<Process*>* tmp = processes->start;
+          processes->start = processes->end;
+          processes->end = tmp;
 
-        processes->start->prev = 0;
-        processes->end->next = 0;
-        processes->end->prev = processes->start;
-        processes->start->next = processes->end;
-      } else {
-        processes->end->next = processes->start;
-        processes->start = processes->start->next;
-        processes->start->prev = 0;
-        xnoe::linkedlistelem<Process*>* tmp = processes->end;
-        processes->end = processes->end->next;
-        processes->end->next = 0;
-        processes->end->prev = tmp;
+          processes->start->prev = 0;
+          processes->end->next = 0;
+          processes->end->prev = processes->start;
+          processes->start->next = processes->end;
+        } else {
+          processes->end->next = processes->start;
+          processes->start = processes->start->next;
+          processes->start->prev = 0;
+          xnoe::linkedlistelem<Process*>* tmp = processes->end;
+          processes->end = processes->end->next;
+          processes->end->next = 0;
+          processes->end->prev = tmp;
+        }
       }
     }
 
     // Get the next process.
-    nextProc = processes->start->elem;
+    if (processes->start)
+      nextProc = processes->start->elem;
+
+    if (nextProc == 0) {
+      Global::kernel->terminal->printf("[FATAL] No more processes! Halting!\n");
+      while (1) asm ("hlt");
+    }
 
     Global::currentProc = nextProc;
 
-    //uint32_t cESP;
-    //asm volatile ("mov %%esp, %0" : "=a" (cESP) :);
-    //currentProc->esp = cESP; // Store the current ESP of the current process process.
-
-    outb(0x20, 0x20);
-
     // Select the next processes page directory
     asm volatile ("mov %0, %%cr3" : : "r" (nextProc->PD->phys_addr)); 
     // Restore kernelStackPtr of the new process.
     asm volatile ("mov %0, %%esp" : : "m" (Global::kernel->processes.start->elem->kernelStackPtr));
 
     // At this point interrupts are disabled till iret so we can safely set
-    // Global::tss->esp0
-    // to the new Process's kernelStackPtrDefault
+    // Global::tss->esp0 to the new Process's kernelStackPtrDefault
 
     Global::tss->esp0 = Global::kernel->processes.start->elem->kernelStackPtrDefault;
 
-    //asm ("popf"); // Pop flags
-    asm ("popa"); // Restore registers
-    asm ("mov -0xc(%ebp), %eax"); // Restore the initial eax
-    // Clear the garbage that was on the stack from previous switch_context call.
-    asm ("mov %ebp, %esp");
-    asm ("pop %ebp"); // Pop EBP
+    // Set the current proc to valid 
+    Global::currentProcValid = true;
 
-    asm ("iret"); // Manually perform iret.
+    uint32_t* espVal;
+    asm ("mov %%esp, %0":"=a"(espVal):);
+    if (*espVal == 0) {
+      asm("add $4, %esp");
+      asm("ret");
+    }
   }
 }
 
 extern uint8_t current_scancode;
 extern char decoded;
 
-__attribute__((interrupt)) void syscall(interrupt_frame* frame) {
+void syscall(frame_struct* frame) {
   // Syscall ABI:
   // 0: print: Print null terminated string (in esi: char*)
   // 1: getch: Get current keyboard character ASCII (out eax: char)
@@ -138,17 +161,11 @@ __attribute__((interrupt)) void syscall(interrupt_frame* frame) {
   // 7: fork: create process from filename (in esi: char* filename)
   // 8: getPID: returns the current process's PID (out eax: uint32_t)
 
-  uint32_t* ebp;
-  asm("mov %%ebp, %0" : "=a" (ebp) :);
-  uint32_t eax = *(ebp-4);
-  uint32_t rval = eax;
+  uint32_t rval = frame->eax;
 
-  uint32_t syscall_number;
-  uint32_t esi;
-  uint32_t edi;
-  asm("mov %%esi, %0" : "=a" (esi) :);
-  asm("mov %%edi, %0" : "=a" (edi) :);
-  switch (eax) {
+  uint32_t esi = frame->esi;
+  uint32_t edi = frame->edi;
+  switch (frame->eax) {
     case 0:
       Global::kernel->terminal->printf("%s", (char*)esi);
       break;
@@ -181,22 +198,25 @@ __attribute__((interrupt)) void syscall(interrupt_frame* frame) {
       break;
   }
 
-  asm volatile ("mov %0, %%eax" : : "m" (rval));
-  asm ("mov %ebp, %esp");
-  asm ("pop %ebp");
-  asm ("iret");
+  frame->eax = rval;
 }
 
 void init_idt() {
   idt_desc desc = {.size = 256 * sizeof(GateEntry) - 1, .offset = (uint32_t)idt};
   asm volatile("lidt %0" : : "m" (desc));
+
   for (int i=0; i<256; i++)
-    set_entry(i, 0x08, &ignore_interrupt, 0x8E);
+    set_entry(i, 0x08, isrs[i], 0xE);
+
+  for (int i=0; i<256; i++)
+    gates[i] = &ignore_interrupt;
   
-  set_entry(0x20, 0x08, &context_switch, 0xE);
-  set_entry(0xD, 0x08, &gpf, 0xE);
-  set_entry(0xE, 0x08, &page_fault, 0xE);
-  set_entry(0x7f, 0x08, &syscall, 0xE, 3);
+  gates[0x20] = &context_switch;
+  gates[0xd] = &gpf;
+  gates[0xe] = &page_fault;
+  gates[0x7f] = &syscall;
+
+  idt[0x7f].privilege = 3;
 
   outb(0x20, 0x11);
   outb(0xA0, 0x11);

src/kernel/idt.h

@@ -7,14 +7,28 @@
 #include "kernel.h"
 #include "gdt.h"
 
-struct interrupt_frame {
-    uint32_t eip;
-    uint16_t cs;
-    uint16_t _ignored0;
-    uint32_t eflags;
+struct __attribute__((packed)) frame_struct {
+  uint32_t edi;
+  uint32_t esi;
+  uint32_t ebp;
+  uint32_t oesp;
+  uint32_t ebx;
+  uint32_t edx;
+  uint32_t ecx;
+  uint32_t eax;
+  uint32_t eip;
+  uint16_t cs;
+  uint16_t _ignored0;
+  uint32_t eflags;
+  uint16_t ss;
+  uint16_t _ignored1;
+  uint32_t esp;
 };
+
+extern void(*gates[256])(frame_struct*);
+
 extern void load_idt();
-void set_entry(uint8_t interrupt_number, uint16_t code_segment, void* handler, uint8_t type, uint8_t privilege = 0);
+void set_entry(uint8_t interrupt_number, uint16_t code_segment, void(*handler)(), uint8_t type, uint8_t privilege = 0);
 void init_idt();
 void enable_idt();
 
@@ -27,11 +41,11 @@ struct __attribute__((packed)) GateEntry{
   uint8_t privilege : 2;
   uint8_t present : 1;
   uint16_t offset_high;
-} ;
+};
 
 struct __attribute__((packed)) idt_desc {
   uint16_t size;
   uint32_t offset;
-} ;
+};
 
 #endif

src/kernel/io.cpp

@@ -1,19 +1,21 @@
 #include "io.h"
 
-void outb(uint16_t portnumber, uint8_t data) {
-  asm volatile("outb %0, %1" : : "a" (data), "Nd" (portnumber));
-}
-uint8_t inb(uint16_t portnumber) {
-  uint8_t result;
-  asm volatile("inb %1, %0" : "=a" (result) : "Nd" (portnumber));
-  return result;
-}
+extern "C" {
+  void outb(uint16_t portnumber, uint8_t data) {
+    asm volatile("outb %0, %1" : : "a" (data), "Nd" (portnumber));
+  }
+  uint8_t inb(uint16_t portnumber) {
+    uint8_t result;
+    asm volatile("inb %1, %0" : "=a" (result) : "Nd" (portnumber));
+    return result;
+  }
 
-void outw(uint16_t portnumber, uint16_t data) {
-  asm volatile("outw %0, %1" : : "a" (data), "Nd" (portnumber));
-}
-uint16_t inw(uint16_t portnumber) {
-  uint16_t result;
-  asm volatile("inw %1, %0" : "=a" (result) : "Nd" (portnumber));
-  return result;
+  void outw(uint16_t portnumber, uint16_t data) {
+    asm volatile("outw %0, %1" : : "a" (data), "Nd" (portnumber));
+  }
+  uint16_t inw(uint16_t portnumber) {
+    uint16_t result;
+    asm volatile("inw %1, %0" : "=a" (result) : "Nd" (portnumber));
+    return result;
+  }
 }

src/kernel/io.h

@@ -3,10 +3,12 @@
 
 #include "types.h"
 
-void outb(uint16_t portnumber, uint8_t data);
-uint8_t inb(uint16_t portnumber);
+extern "C" {
+  void outb(uint16_t portnumber, uint8_t data);
+  uint8_t inb(uint16_t portnumber);
 
-void outw(uint16_t portnumber, uint16_t data);
-uint16_t inw(uint16_t portnumber);
+  void outw(uint16_t portnumber, uint16_t data);
+  uint16_t inw(uint16_t portnumber);
+}
 
 #endif

src/kernel/isr.S.base

@@ -0,0 +1,52 @@
+[BITS 32]
+
+global isrs
+
+global catchall_return
+
+catchall: ; At this point the gate number has been pushed to the stack
+  pushad ; Pushed 32 bytes
+  mov eax, [esp+32]
+  mov ebx, gates
+  mov eax, [ebx+4*eax]
+  push esp
+  call eax
+
+catchall_return:
+  add esp, 4
+
+  push 0x20
+  push 0x20
+  call outb
+  add esp, 8
+
+  popad
+  mov esp, ebp
+  pop ebp
+  iret
+
+extern gates ; (void(*)(frame_struct))*
+extern outb 
+
+; struct frame_struct __attribute__((packed)) {
+; popad
+;   uint32_t edi;
+;   uint32_t esi;
+;   uint32_t ebp;
+;   uint32_t esp;
+;   uint32_t ebx;
+;   uint32_t edx;
+;   uint32_t ecx;
+;   uint32_t eax;
+;
+; interrupt
+;   uint32_t eip;
+;   uint32_t cs;
+;   uint32_t eflags;
+;   uint32_t esp;
+;   uint32_t ss;
+;  
+; if it's an error
+;   uint32_t err_code;
+; }
+

src/kernel/kernel.cpp

@@ -1,6 +1,6 @@
 #include "kernel.h"
 
-Kernel::Kernel(PageDirectory* page_directory, PageMap* phys, PageMap* virt, uint32_t virt_alloc_base)
+Kernel::Kernel(PageDirectory* page_directory, PageMap* phys, PageMap* virt, uint32_t virt_alloc_base, uint32_t stack)
   : Process(0, 0x8a000, page_directory, phys, virt, virt_alloc_base)
 {
   this->currentPID = 1;
@@ -9,6 +9,8 @@ Kernel::Kernel(PageDirectory* page_directory, PageMap* phys, PageMap* virt, uint
 
   Global::currentProc = 0;
 
+  this->stack = stack;
+
   //this->processes.append(this);
 }
 
@@ -30,5 +32,8 @@ void Kernel::destroyProcess(Process* p) {
   this->processes.remove(p);
   this->pid_map->remove(p->PID, p);
   delete p;
-  while (1);
-}
+}
+
+//void Kernel::loadPrimaryStack() {
+//  asm volatile("mov %0, %%esp"::"m"(this->stack - 64));
+//}

src/kernel/kernel.h

@@ -9,18 +9,20 @@
 class Kernel : public Process {
 public:
   uint32_t currentPID;
+  uint32_t stack;
   Terminal* terminal;
 
   xnoe::hashtable<uint32_t, Process*>* pid_map; // Map of PIDs -> Process*s
 
   xnoe::linkedlist<Process*> processes;
 
-  Kernel(PageDirectory* page_directory, PageMap* phys, PageMap* virt, uint32_t virt_alloc_base);
+  Kernel(PageDirectory* page_directory, PageMap* phys, PageMap* virt, uint32_t virt_alloc_base, uint32_t stack);
 
   void init_kernel();
 
   Process* createProcess(char* filename);
   void destroyProcess(Process* p);
+  //void loadPrimaryStack();
 };
 
 #endif

src/kernel/keyboard.cpp

@@ -36,7 +36,7 @@ char decoded = 0;
 bool caps_on = false;
 bool shift_on = false;
 
-__attribute__((interrupt)) void keyboard_interrupt(struct interrupt_frame* frame) {
+void keyboard_interrupt(frame_struct* frame) {
   current_scancode = inb(0x60);
   outb(0x20, 0x21);
   if ((current_scancode&0x7f) == 0x2a)
@@ -54,7 +54,8 @@ __attribute__((interrupt)) void keyboard_interrupt(struct interrupt_frame* frame
 }
 
 void init_keyboard() {
-  set_entry(0x21, 0x08, &keyboard_interrupt, 0x8E);
+  //set_entry(0x21, 0x08, &keyboard_interrupt, 0x8E);
+  gates[0x21] = &keyboard_interrupt;
 
   while (inb(0x64) & 1) {
     inb(0x60);

src/kernel/kmain.cpp

@@ -27,7 +27,7 @@ int main() {
   PageMap phys_pm(0xc0600000);
   PageMap virt_pm(0xc0620000);
 
-  Kernel kernel = Kernel(&kernel_pd, &phys_pm, &virt_pm, 0xc0000000);
+  Kernel kernel = Kernel(&kernel_pd, &phys_pm, &virt_pm, 0xc0000000, 0xc1006000);
   kernel.init_kernel();
   init_atapio();
 
@@ -47,6 +47,7 @@ int main() {
   Global::currentProc = &kernel;
 
   Process* p1 = kernel.createProcess("WORLD   BIN");
+  kernel.createProcess("HELLO   BIN");
 
   init_keyboard();
   

src/kernel/process.cpp

@@ -1,5 +1,7 @@
 #include "process.h"
 
+extern void(*catchall_return)();
+
 AllocTracker::AllocTracker(void* base, uint32_t size, uint32_t count) : page_base(base), page_size(size), alloc_count(count) {}
 
 xnoe::Maybe<xnoe::linkedlistelem<AllocTracker>*> Process::get_alloc_tracker(uint32_t address) {
@@ -68,8 +70,6 @@ Process::Process(uint32_t PID, PageDirectory* inherit, uint32_t inheritBase, cha
 
   uint32_t rEBP = stack32;
 
-  stack32 -= 21;
-
   stack32--;
   *stack32 = 0; // EAX
   stack32--;
@@ -87,6 +87,13 @@ Process::Process(uint32_t PID, PageDirectory* inherit, uint32_t inheritBase, cha
   stack32--;
   *stack32 = 0; // EDI
 
+  stack32--;
+
+  stack32--;
+  *stack32 = &catchall_return; // cachall_return
+
+  stack32--;
+
   this->kernelStackPtr = stack32;
 
   load_file(filename, program_data);

src/kernel/terminal.cpp

@@ -58,6 +58,20 @@ void Terminal::printf(const char* string, ...) {
       this->cur_y++;
     }
 
+    if (current == '\b') {
+      if (this->cur_x > 0) {
+        this->cur_x--;
+      } else {
+        this->cur_y--;
+        this->cur_x = this->width-1;
+      }
+
+      int mem_pos = this->cur_y * this->width + this->cur_x;
+      
+      this->putchar(mem_pos, ' ');
+      continue;
+    }
+
     if (this->cur_x == this->width) {
       this->cur_x = 0;
       this->cur_y++;

src/world/world.c

@@ -2,7 +2,7 @@
 #include <stdbool.h>
 
 char key_to_char[128] = {
-  0, 0, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-', '=', 0, 0, 
+  0, 0, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-', '=', '\b', 0, 
   'q', 'w', 'e', 'r', 't', 'y', 'u', 'i', 'o', 'p', '[', ']', 0,
   0, 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', ';', '\'', '`', 0, '\\',
   'z', 'x', 'c', 'v', 'b', 'n', 'm', ',', '.', '/', 0, '*', 0, ' ', 0, 0,
@@ -12,7 +12,7 @@ char key_to_char[128] = {
 };
 
 char key_to_char_caps[128] = {
-  0, 0, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-', '=', 0, 0, 
+  0, 0, '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '-', '=', '\b', 0, 
   'Q', 'W', 'E', 'R', 'T', 'Y', 'U', 'I', 'O', 'P', '[', ']', 0,
   0, 'A', 'S', 'D', 'F', 'G', 'H', 'J', 'K', 'L', ';', '\'', '`', 0, '\\',
   'Z', 'X', 'C', 'V', 'B', 'N', 'M', ',', '.', '/', 0, '*', 0, ' ', 0, 0,
@@ -22,7 +22,7 @@ char key_to_char_caps[128] = {
 };
 
 char key_to_char_shift[128] = {
-  0, 0, '!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '_', '+', 0, 0, 
+  0, 0, '!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '_', '+', '\b', 0, 
   'Q', 'W', 'E', 'R', 'T', 'Y', 'U', 'I', 'O', 'P', '{', '}', 0,
   0, 'A', 'S', 'D', 'F', 'G', 'H', 'J', 'K', 'L', ':', '"', '~', 0, '|',
   'Z', 'X', 'C', 'V', 'B', 'N', 'M', ',', '.', '/', 0, '*', 0, ' ', 0, 0,
@@ -54,12 +54,6 @@ void readline(int max, char* buffer) {
     if (scancode == 0x3a)
       caps_on ^= 1;
 
-    /*if (scancode == 0x0e && index > 0) {
-      set_curpos_raw(get_curpos()-1);
-      non_moving_put(' ');
-      buffer[--index] = 0;
-    }*/
-
     if (shift_on)
       decoded = key_to_char_shift[scancode&0x7f];
     else if (caps_on)
@@ -67,7 +61,12 @@ void readline(int max, char* buffer) {
     else
       decoded = key_to_char[scancode&0x7f];
 
-    if (decoded && scancode < 0x80) {
+    if (scancode == 0x0e) {
+      if (index > 0) {
+        buffer[--index] = 0;
+        print("\b");
+      }
+    } else if (decoded && scancode < 0x80) {
       buffer[index++] = decoded;
       char_print[0] = decoded;
       print(char_print);

src/world/world.ld

@@ -1,14 +1,14 @@
 OUTPUT_FORMAT(binary)
 OUTPUT_ARCH(i386:i386)
 
-OUTPUT(build/program/world.bin)
+OUTPUT(build/world/world.bin)
 
 SECTIONS {
   . = 0x8020;
 
   .text : {
     build/program_code_entry.o(.text)
-    build/program/world.o(.text)
+    build/world/world.o(.text)
     build/common/common.o(.text)
   }
 }