Made malloc() and free()! They're in header stdlib.h as syscalls 3 & 4.

include/c/stdlib.h

@@ -0,0 +1,18 @@
+#ifndef STDLIB_H
+#define STDLIB_H
+
+#include <stdint.h>
+
+void* malloc(const uint32_t size) { // Use Syscall(3) - Malloc()
+    void* ptr = 0;
+    __asm__ volatile ("int $0x80" : : "a"(3), "b"(size));
+    __asm__ volatile ("movl %%eax, %0" : "=r"(ptr));
+
+    return ptr;
+}
+
+void free(const void* ptr) { // Use Syscall(4) - Free()
+    __asm__ volatile ("int $0x80" : : "a"(4), "b"(ptr));
+}
+
+#endif

include/interrupt/syscall.h

@@ -1,12 +1,14 @@
 #ifndef SYSCALL_H
 #define SYSCALL_H
 
+#include <interrupt/idt.h>
 #include <interrupt/pit.h>
 #include <screen/text.h>
 #include <keyboard/keyboard.h>
+#include <memory/malloc.h>
 
 // System call count
-#define MAX_SYSCALLS 3
+#define MAX_SYSCALLS 5
 
 // Args: ebx - number of miliseconds
 void sys_sleep() {
@@ -35,22 +37,48 @@ void sys_gets() {
     read(s);
 }
 
+// Args: ebx - amount of bytes to malloc
+void sys_malloc() {
+    uint32_t size = 0;
+    __asm__ volatile ("movl %%ebx, %0" : "=b"(size));
+    
+    // First Malloc()
+    if (!mallocListHead) {
+        mallocInit(size); // Setup malloc linked list
+    }
+
+    void* ptr = mallocNextNode(size);
+    mallocMergeFree();
+
+    // Return allocated address in eax
+    __asm__ volatile ("movl %0, %%eax" : : "r"(ptr));
+}
+
+// Args: ebx - allocated pointer
+void sys_free() {
+    void* ptr = NULL;
+    __asm__ volatile ("movl %%ebx, %0" : "=b"(ptr));
+    mallocFree(ptr);
+}
+
 // System call table
 void* syscalls[MAX_SYSCALLS] = {
-    sys_sleep, // Syscall(0)
-    sys_puts,  // Syscall(1)
-    sys_gets,  // Syscall(2)
+    sys_sleep,  // Syscall(0)
+    sys_puts,   // Syscall(1)
+    sys_gets,   // Syscall(2)
+    sys_malloc, // Syscall(3)
+    sys_free,   // Syscall(4)
 };
 
 // int 0x80 - Syscall interrupt, handled by this function
 // eax : Syscall number
 __attribute__ ((naked)) // No prologue or epilogue, just assembly
-void syscallHandler(void) {
+void syscallHandler(intFrame_t* iframe) {
     // Interrupt - Stack should contain: ss, esp, eflags, cs, eip
     // We should also push these regs: ax, gs, fs, es, ds, bp, di, si, dx, cx, bx
     __asm__ volatile (
             ".intel_syntax noprefix\n" // We use intel syntax
-            ".equ MAX_SYSCALLS, 3\n" // Define MAX_SYSCALLS again TODO: I don't want to have to do this
+            ".equ MAX_SYSCALLS, 5\n" // Define MAX_SYSCALLS again TODO: I don't want to have to do this
 
             // Check if syscall exists
             "cmp eax, MAX_SYSCALLS - 1\n"
@@ -86,6 +114,7 @@ void syscallHandler(void) {
 
             // TODO: Send an error or something here
             "invalidSyscall:\n"
+            "mov eax, -1\n" // Current error thing
             "iretd\n"
 
             ".att_syntax" // Switch back to Att Syntax (Just in case)

include/memory/malloc.h

@@ -0,0 +1,124 @@
+#ifndef MALLOC_H
+#define MALLOC_H
+
+#include <stdint.h>
+#include <memory/virtual.h>
+#include <memory/physical.h>
+#include <stdbool.h>
+
+// Singly linked list!
+typedef struct mallocNode_s {
+    uint32_t size;
+    bool free;
+    struct mallocNode_s* next;
+} mallocNode_t;
+
+mallocNode_t* mallocListHead = NULL;
+static uint32_t mallocVirtualAddr = 0;
+static uint32_t mallocPhysicalAddr = 0;
+static uint32_t mallocPages = 0;
+
+void mallocInit(uint32_t size) {
+    mallocPages = size / PAGE_SIZE;
+    if (size % PAGE_SIZE > 0) { mallocPages++; }
+
+    mallocPhysicalAddr = (uint32_t)allocBlocks(mallocPages);
+    mallocListHead = (mallocNode_t*)mallocVirtualAddr;
+    
+    // Map pages
+    for (uint32_t i = 0, virtualAddr = mallocVirtualAddr; i < mallocPages; i++, virtualAddr += PAGE_SIZE) {
+        mapPage((void*)(mallocPhysicalAddr + i * PAGE_SIZE), (void*)virtualAddr);
+
+        ptEntry_t* page = getPage(virtualAddr);
+        SET_ATTR(page, PTE_READ_WRITE);
+    }
+
+    if (mallocListHead) {
+        mallocListHead->size = (mallocPages * PAGE_SIZE) - sizeof(mallocNode_t);
+        mallocListHead->free = true;
+        mallocListHead->next = NULL;
+    }
+}
+
+void mallocSplit(mallocNode_t* node, uint32_t size) {
+    if (node->size < size + sizeof(mallocNode_t)) { return; } // Can't split - node too small
+    
+    // Remainder node
+    mallocNode_t* newNode = (mallocNode_t*)((void*)node + size + sizeof(mallocNode_t));
+    newNode->size = node->size - size - sizeof(mallocNode_t);
+    newNode->free = true;
+    newNode->next = node->next;
+
+    // Split node
+    node->size = size;
+    node->free = false;
+    node->next = newNode;
+}
+
+void* mallocNextNode(uint32_t size) {
+    if (size == 0) { return NULL; } // Why would you try that? (undefined behaviour i guess)
+    
+    mallocNode_t* current = mallocListHead;
+
+    if (mallocListHead->size == 0) { mallocInit(size); }
+    
+    while (((current->size < size) || !current->free) && current->next != NULL) {
+        current = current->next;
+    }
+
+    if (current->size == size) {
+        current->free = false;
+    } else if (current->size > size + sizeof(mallocNode_t)) {
+        mallocSplit(current, size); // Modifies current into the right size and makes it point to the remainder
+    } else { // There's no large enough node -> try to allocate more pages
+        uint8_t pageCount = 1;
+        while (current->size + pageCount * PAGE_SIZE < size + sizeof(mallocNode_t)) { 
+            pageCount++;
+        }
+
+        // Allocate and map new pages
+        uint32_t virtualAddr = mallocVirtualAddr + mallocPages * PAGE_SIZE;
+        for (uint32_t i = 0; i < pageCount; i++) {
+            ptEntry_t page = 0;
+            uint32_t* temp = allocPage(&page);
+
+            mapPage((void*)temp, (void*)virtualAddr);
+            SET_ATTR(&page, PTE_READ_WRITE);
+            virtualAddr += PAGE_SIZE;
+            current->size += PAGE_SIZE;
+            mallocPages++;
+        }
+
+        mallocSplit(current, size);
+    }
+
+    return (void*)current + sizeof(mallocNode_t);
+}
+
+void mallocMergeFree() {
+    mallocNode_t* current = mallocListHead;
+
+    while (current && current->next != NULL) {
+        if (current->free && current->next->free) {
+            current->size += (current->next->size) + sizeof(mallocNode_t);
+            current->next = current->next->next;
+        }
+        current = current->next;
+    }
+}
+
+void mallocFree(void* ptr) {
+    mallocNode_t* current = mallocListHead;
+
+    while (current->next) {
+        if ((void*)current + sizeof(mallocNode_t) == ptr) {
+            current->free = true;
+            mallocMergeFree();
+            break;
+        }
+
+        current = current->next;
+    }
+}
+
+#endif

src/calc.c

@@ -1,6 +1,5 @@
 #include <stdio.h>
 
-__attribute__ ((section ("entry")))
 void main() {
     char msg[8] = { 'H','e','l','l','o','!','\n',0 };
     print(msg);

src/calc.ld

@@ -1,6 +1,6 @@
+ENTRY("main");
 SECTIONS {
     .text : {
-        *(entry); 
         *(.text*);
     }
     .data : {
@@ -13,3 +13,4 @@ SECTIONS {
         *(.bss*);
     }
 }
+

src/kernel.c

@@ -16,6 +16,7 @@
 #include <sound/notes.h>
 #include <memory/virtual.h>
 #include <memory/addresses.h>
+#include <memory/malloc.h>
 
 #define PROMPT "#> "
 
@@ -303,8 +304,29 @@ void main() {
 
                     diskRead(sector, size, entryPoint);
 
-                    if (strcmp(fileType, "bin") == 0) { // TODO: Improve this
+                    if (strcmp(fileType, "bin") == 0) {
+                        // Reset malloc
+                        mallocListHead = NULL;
+                        mallocVirtualAddr = (uint32_t)entryPoint + neededPages * PAGE_SIZE;
+                        mallocPhysicalAddr = 0;
+                        mallocPages = 0;
+
                         ((void(*)(void))entryPoint)(); // Call program
+
+                        for (uint32_t i = 0, virtualAddr = mallocVirtualAddr; i < mallocPages; i++, virtualAddr += PAGE_SIZE) {
+                            ptEntry_t* page = getPage(virtualAddr);
+
+                            if (PAGE_PHYS_ADDRESS(page) && TEST_ATTR(page, PTE_PRESENT)) {
+                                freePage(page);
+                                unmapPage((void*)virtualAddr);
+                                flushTlbEntry(virtualAddr);
+                            }
+                        }
+
+                        mallocListHead = NULL;
+                        mallocVirtualAddr = 0;
+                        mallocPhysicalAddr = 0;
+                        mallocPages = 0;
                     } else if (strcmp(fileType, "tab") == 0) {
                         printFiletable(entryPoint);
                     } else if (strcmp(fileType, "fnt") == 0) {

todo.txt

@@ -89,13 +89,12 @@ Legend:
         - [ ] Hard
 - [ ] System Calls
     - [x] Sleep()
-    - [x] Print() - Temporary for printing before we get Write(stdout) :)
-    - [ ] Write()
-    - [ ] Read()
+    - [ ] Write() (temporarly puts())
+    - [ ] Read() (temporarly gets())
     - [ ] Open()
     - [ ] Close()
-    - [ ] Malloc()
-    - [ ] Free()
+    - [x] Malloc()
+    - [x] Free()
     - [ ] Seek()
 - [ ] Shell
     - [ ] Separate file/program
@@ -126,10 +125,13 @@ Legend:
     - [x] Loading them
     - [x] Running them
     - [x] Exit back to kernel/shell
-    - [ ] Let them use libs
+    - [x] Let them use libs
     - [ ] Proper include files (LibC?)
     - [ ] argc, argv[]
 - [ ] Standalone shell program
+- [ ] Userspace programs
+    - [ ] Calculator
+    - [ ] Caledar
 - [ ] Code Editor
     - [ ] Text editor
     - [ ] Syntax highlighting
@@ -145,4 +147,5 @@ Legend:
 - [ ] Games
     - [ ] Minesweeper
     - [ ] Solitaire
+    - [ ] Tetris