Fix ifndef names. Remove useless summation

These "tags" hold the pointers between the alloced blocks.

.gitignore

@@ -1 +1,5 @@
 target/
+
+.idea/
+CMakeLists.txt
+cmake-build-debug/

README.md

@@ -37,7 +37,7 @@ The kernel is based on [the bare bones kernel from the OSDev wiki](https://wiki.
   - [ ] Write files in directory
 - [ ] Tests
 - [ ] Running executables from filesystem
-- [ ] Better memory management
+- [x] Better memory management
 - [ ] Better shell
 
 As a test, I've implemented day 1 of [advent of code](https://adventofcode.com/) on the [AoC branch](https://github.com/Robbe7730/RoBoot/tree/AoC).

bootloader/main.asm

@@ -290,7 +290,7 @@ repnz movsd
 or ax, ax
 jnz .elf_ph_loop
 
-.start_kernel
+.start_kernel:
 
 cmp edi, KERNEL_START
 je .invalid_elf

kernel/kernel.c

@@ -2,7 +2,7 @@
 #if defined(__linux__)
 #error "You are not using a cross-compiler, you will most certainly run into trouble"
 #endif
- 
+
 /* This tutorial will only work for the 32-bit ix86 targets. */
 #if !defined(__i386__)
 #error "This kernel needs to be compiled with a ix86-elf compiler"
@@ -16,52 +16,67 @@
 #include "memory.c"
 #include "interrupts.c"
 #include "shell.c"
+#include "util/printer.c"
 
 static inline bool are_interrupts_enabled() {
     unsigned long flags;
     asm volatile ( "pushf\n\t"
                    "pop %0"
-                   : "=g"(flags) );
+    : "=g"(flags));
     return flags & (1 << 9);
 }
 
-void kernel_main(void) 
-{
-	/* Initialize terminal interface */
-	terminal_initialize();
+void kernel_main(void) {
+    /* Initialize terminal interface */
+    terminal_initialize();
+
+    terminal_putchar('H');
+    terminal_putchar('e');
+    terminal_putchar('l');
+    terminal_putchar('l');
+    terminal_putchar('o');
 
-	terminal_putchar('H');
-	terminal_putchar('e');
-	terminal_putchar('l');
-	terminal_putchar('l');
-	terminal_putchar('o');
- 
     terminal_setcolor(vga_entry_color(VGA_COLOR_GREEN, VGA_COLOR_BLACK));
-    terminal_writestring(" kernel");
+    print(" kernel");
     terminal_setcolor(vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK));
-    terminal_writestring(" World!\n");
-	terminal_writestring("Newlines!\n");
+    print(" World!\n");
+    print("Newlines!\n");
 
-	char* memory_str = alloc(sizeof(char) * 7);
-	for (int i = 0; i < 6; i++) {
-		memory_str[i] = "Memory"[i];
-	}
-	memory_str[6] = 0;
+    char *memory_str = alloc(sizeof(char) * 7);
+    for (int i = 0; i < 6; i++) {
+        memory_str[i] = "Memory"[i];
+    }
+    memory_str[6] = 0;
 
-	char* management_str = alloc(sizeof(char) * 13);
-	for (int i = 0; i < 13; i++) {
-		management_str[i] = " management!\n"[i];
-	}
-	management_str[13] = 0;
+    char *management_str = alloc(sizeof(char) * 13);
+    for (int i = 0; i < 13; i++) {
+        management_str[i] = " management!\n"[i];
+    }
+    management_str[13] = 0;
 
-	terminal_writestring(memory_str);
-	terminal_writestring(management_str);
+    print(memory_str);
+    print(management_str);
 
-	terminal_writestring((are_interrupts_enabled())? "Interrupts!\n": "No interrupts :(\n");
+    free(memory_str);
+    free(management_str);
 
-	interrupt_init();
+    // Some dummy allocations to demonstrate the states of memory and to showcase the memory dump printout.
+    void* ptr = alloc(30);
+    alloc(30);
+    alloc(31);
+    free(ptr);
 
-	for(;;) {
-		shell_step();
-	}
+    void* ptr2 = alloc(64);
+    alloc(61);
+    free(ptr2);
+
+    print((are_interrupts_enabled()) ? "Interrupts!\n" : "No interrupts :(\n");
+
+    interrupt_init();
+
+    print_memory();
+
+    for (;;) {
+        shell_step();
+    }
 }

kernel/memory.c

@@ -1,13 +1,208 @@
 #ifndef MEMORY_C
 #define MEMORY_C
 
+
 #include <stddef.h>
 
-void* _curr_end = (void*) 0x200000;
+#include "terminal.c"
+#include "util/printer.c"
 
-void* alloc(size_t size) {
-    void* thanks_jp = _curr_end;
-    _curr_end += size;
-    return thanks_jp;
+#define MEMORY_START 0x200000
+//#define MEMORY_END 0x300000
+
+#define PAGE_ALIGNMENT 4
+
+//size_t total_memory = MEMORY_END - MEMORY_START;
+
+typedef struct page_tag {
+    size_t size;
+    size_t realsize;
+
+    struct page_tag *prev;
+    struct page_tag *next;
+} page_tag;
+
+
+page_tag *start = (void *) MEMORY_START;;
+
+size_t calculate_realsize(size_t size) {
+    if (size % PAGE_ALIGNMENT == 0) return size;
+    return size + PAGE_ALIGNMENT - (size % PAGE_ALIGNMENT);
 }
-#endif // MEMORY_C
+
+void *alloc(size_t size) {
+    page_tag *curr_page = start;
+
+    while (curr_page->next != NULL) {
+        page_tag *new_page = ((void *) curr_page) + sizeof(page_tag) + curr_page->realsize;
+        size_t realsize = calculate_realsize(size);
+        if ((void *) new_page + sizeof(page_tag) + realsize <= (void *) curr_page->next) {
+
+            new_page->size = size;
+            new_page->realsize = realsize;
+
+            curr_page->next->prev = new_page;
+            new_page->next = curr_page->next;
+
+            curr_page->next = new_page;
+            new_page->prev = curr_page;
+
+            return new_page + 1;
+        }
+        curr_page = curr_page->next;
+    }
+
+    page_tag *new_page = ((void *) curr_page) + sizeof(page_tag) + curr_page->realsize;
+    new_page->size = size;
+    new_page->realsize = calculate_realsize(size);
+
+    curr_page->next = new_page;
+    new_page->prev = curr_page;
+    new_page->next = NULL;
+    return new_page + 1;
+}
+
+void free(void *data) {
+    page_tag *data_tag = data - sizeof(page_tag);
+
+    data_tag->prev->next = data_tag->next;
+    data_tag->next->prev = data_tag->prev;
+}
+
+int amount_of_digits(int x) {
+    if (x == 0) return 1;
+    int n = 0;
+    while (x != 0) {
+        n += 1;
+        x /= 10;
+    }
+    return n;
+}
+
+#define MEM_SIZE_WIDTH 3
+#define SPACED_ARRAY {' ', ' ', ' '};
+
+void print_memory() {
+    print("____________________\n");
+    print(" ===  MEM DUMP  === \n");
+    print("--------------------\n");
+    print("Page tag size:    %d bytes\n", sizeof(page_tag));
+    print("Memory alignment:  %d bytes\n", PAGE_ALIGNMENT);
+    print("=> idx: [page_tag_address] [data_address (size|aligment_padding_size)]\n\n");
+    page_tag *curr_page = start;
+    int i = 0;
+    bool left = true;
+    while (curr_page != NULL) {
+        char padding[MEM_SIZE_WIDTH] = SPACED_ARRAY;
+        padding[MEM_SIZE_WIDTH - amount_of_digits(curr_page->size)] = '\0';
+        print("%d: [%x] [%x (%s%d|%d)]",
+              i,
+              curr_page,
+              (curr_page + 1), padding, curr_page->size,
+              curr_page->realsize - curr_page->size);
+
+        if (left) {
+            print(" | ");
+        } else {
+            print("\n");
+        }
+        left = !left;
+
+        bool empty_print = false;
+        void *empty_start = (void *) curr_page + sizeof(page_tag) + curr_page->realsize;
+        if (empty_start + sizeof(page_tag) < (void *) curr_page->next) {
+            size_t memory_left = (void *) curr_page->next -
+                                 (empty_start + sizeof(page_tag));
+            char empty_padding[MEM_SIZE_WIDTH] = SPACED_ARRAY;
+            empty_padding[MEM_SIZE_WIDTH - amount_of_digits(memory_left)] = '\0';
+
+            print("_: free space      (%d + %s%d| ) ",
+                  sizeof(page_tag),
+                  empty_padding,
+                  memory_left
+            );
+            empty_print = true;
+        } else if (empty_start < (void *) curr_page->next) {
+            size_t memory_left = (void *) curr_page->next - empty_start;
+
+            char empty_padding[MEM_SIZE_WIDTH] = SPACED_ARRAY;
+            empty_padding[MEM_SIZE_WIDTH - amount_of_digits(memory_left)] = '\0';
+
+            print("_: not enough room      (%s%d| ) ",
+                  empty_padding,
+                  memory_left);
+            empty_print = true;
+        }
+        if (empty_print) {
+            if (left) {
+                print(" | ");
+            } else {
+                print("\n");
+            }
+            left = !left;
+        }
+
+
+        curr_page = curr_page->next;
+        i += 1;
+    }
+    if (!left) {
+        print("\n");
+    }
+    print("____________________\n");
+}
+
+int command_mem_dump(char *string) {
+    print_memory();
+}
+
+//
+//void test_allocs() {
+//    void *ptr0 = __alloc(64);
+//    void *ptr1 = __alloc(64);
+//    void *ptr4 = __alloc(64);
+//    print();
+//
+//    printf("Free nr 2 -> %p\n", ptr1);
+//    __free(ptr1);
+//    print();
+//
+//    printf("Alloc 32 bytes\n");
+//    void *ptr2 = __alloc(32);
+//    print();
+//
+//    printf("Alloc 32 bytes\n");
+//    __alloc(32);
+//    print();
+//
+//    printf("Alloc 8 bytes\n");
+//    void *ptr3 = __alloc(8);
+//    print();
+//
+//    __free(ptr2);
+//    print();
+//    __free(ptr4);
+//    print();
+//    __free(ptr3);
+//    print();
+//
+//    __free(ptr0);
+//    print();
+//
+//    printf("#########\nTry almost fill\n");
+//    __alloc(160);
+//    print();
+//    __alloc(50);
+//    print();
+//
+//
+//}
+//
+//int main() {
+//    start = malloc(sizeof(size_t) * 1000);
+//    start->next = NULL;
+//    start->prev = NULL;
+//    test_allocs();
+//}
+
+#endif // MEMORY_C

kernel/shell.c

@@ -8,28 +8,29 @@
 #include "terminal.c"
 #include "inline_asm.c"
 #include "drivers/keyboard/keyboard.c"
+#include "memory.c"
 
 char buffer[SHELL_CMD_BUFFER_SIZE];
 int buffer_idx = 0;
 
-int echo(char* input) {
+int echo(char *input) {
     terminal_writestring(input);
     terminal_putchar('\n');
     return 0;
 }
 
-int hello(char* unused) {
+int hello(char *unused) {
     terminal_writestring("Hello, world!\n");
     return 0;
 }
 
-int cls(char* unused) {
+int cls(char *unused) {
     terminal_initialize();
     return 0;
 }
 
-int get_gdt(char* unused) {
-    gdt_desc desc = {2,2};
+int get_gdt(char *unused) {
+    gdt_desc desc = {2, 2};
     sgdt(&desc);
     terminal_writestring("limit = ");
     terminal_writeint(desc.limit, 10);
@@ -37,79 +38,77 @@ int get_gdt(char* unused) {
     terminal_writeint(desc.base, 16);
     terminal_putchar('\n');
 
-    gdt_entry* entries = (gdt_entry*) desc.base;
-    int num_entries = (desc.limit+1) / 8;
+    gdt_entry *entries = (gdt_entry *) desc.base;
+    int num_entries = (desc.limit + 1) / 8;
     for (int entry_num = 0; entry_num < num_entries; entry_num++) {
         gdt_entry entry = entries[entry_num];
         uint32_t base = entry.base_lower | entry.base_middle << 16 | entry.base_higher << 24;
         uint32_t limit = entry.limit_lower | (entry.flags_limit_higher & 0x0f) << 16;
         uint8_t flags = (entry.flags_limit_higher >> 4);
         bool is_data = ((entry.access_byte & 0b00001000) >> 3) == 0;
-        
+
         //terminal_writestring("\nEntry ");
         //terminal_writeint(entry_num, 10);
-        terminal_writestring("base = 0x");
-        terminal_writeint(base, 16);
-        terminal_writestring("\nlimit = 0x");
-        terminal_writeint(limit, 16);
-        terminal_writestring("\nflags = 0b");
-        terminal_writeint((entry.flags_limit_higher >> 4), 2);
+        print("base = %x\n", base);
+        print("limit = %x\n", limit);
+        print("flags = %b\n", (entry.flags_limit_higher >> 4));
 
         if ((flags & 0b1000) == 0) {
-            terminal_writestring(" (byte granularity");
+            print(" (byte granularity");
         } else {
-            terminal_writestring(" (page granularity");
+            print(" (page granularity");
         }
 
         if ((flags & 0b0100) == 0) {
-            terminal_writestring(", 16 bit)");
+            print(", 16 bit)");
         } else {
-            terminal_writestring(", 32 bit)");
+            print(", 32 bit)");
         }
+        print("\n");
 
-        terminal_writestring("\naccess = 0b");
-        terminal_writeint(entry.access_byte, 2);
-        terminal_writestring(" (ring ");
-        terminal_writeint((entry.access_byte & 0b01100000) >> 5, 10);
+        print("access = %b (ring %d",
+              entry.access_byte,
+              (entry.access_byte & 0b01100000) >> 5
+        );
         if ((entry.access_byte & 0b00010000) == 0) {
-            terminal_writestring(", System");
+            print(", System");
         }
         if (is_data) {
-            terminal_writestring(", Data");
+            print(", Data");
 
-            if((entry.access_byte & 0b00000100) == 0) {
-                terminal_writestring(" (growing up, ");
+            if ((entry.access_byte & 0b00000100) == 0) {
+                print(" (growing up, ");
             } else {
-                terminal_writestring(" (growing down, ");
+                print(" (growing down, ");
             }
 
-            if((entry.access_byte & 0b00000010) == 0) {
-                terminal_writestring("r--)");
+            if ((entry.access_byte & 0b00000010) == 0) {
+                print("r--)");
             } else {
-                terminal_writestring("rw-)");
+                print("rw-)");
             }
         } else {
-            terminal_writestring(", Code");
+            print(", Code");
 
-            if((entry.access_byte & 0b00000100) == 0) {
-                terminal_writestring(" (non-conforming, ");
+            if ((entry.access_byte & 0b00000100) == 0) {
+                print(" (non-conforming, ");
             } else {
-                terminal_writestring(" (conforming, ");
+                print(" (conforming, ");
             }
 
-            if((entry.access_byte & 0b00000010) == 0) {
-                terminal_writestring("--x)");
+            if ((entry.access_byte & 0b00000010) == 0) {
+                print("--x)");
             } else {
-                terminal_writestring("r-x)");
+                print("r-x)");
             }
         }
 
-        terminal_writestring(")\n");
+        print(")\n");
     }
     return 0;
 }
 
-int ree(char* unused) {
+int ree(char *unused) {
     terminal_initialize();
     terminal_putchar('R');
     for (int i = 1; i < VGA_WIDTH * VGA_HEIGHT; i++) {
@@ -118,27 +117,41 @@ int ree(char* unused) {
     return 0;
 }
 
+int save_text(char *text) {
+    char *mem_block = alloc(strlen(text) * sizeof(char));
+    char *c;
+    int i = 0;
+    for (c = text; *c != '\0'; c++) {
+        mem_block[i] = *c;
+        i++;
+    }
+}
+
 // TODO This is ugly, fix this 
-const char* shell_commands_strings[] = {
-    "echo",
-    "hello",
-    "cls",
-    "ree",
-    "getgdt",
-    NULL
+const char *shell_commands_strings[] = {
+        "echo",
+        "hello",
+        "cls",
+        "ree",
+        "getgdt",
+        "memdump",
+        "savetext",
+        NULL
 };
 
-int (*shell_commands_functions[]) (char*) = {
-    echo,
-    hello,
-    cls,
-    ree,
-    get_gdt
+int (*shell_commands_functions[])(char *) = {
+        echo,
+        hello,
+        cls,
+        ree,
+        get_gdt,
+        command_mem_dump,
+        save_text
 };
 
-int run_command(char* buffer) {
+int run_command(char *buffer) {
 
-    if(buffer[0] == 0) {
+    if (buffer[0] == 0) {
         return 0;
     }
     char command[SHELL_CMD_BUFFER_SIZE] = {0};
@@ -150,9 +163,9 @@ int run_command(char* buffer) {
 
     int command_idx = 0;
 
-    while(shell_commands_strings[command_idx] != NULL) {
+    while (shell_commands_strings[command_idx] != NULL) {
         int check_idx = 0;
-        while(command[check_idx] != 0 && shell_commands_strings[command_idx][check_idx] == command[check_idx]) {
+        while (command[check_idx] != 0 && shell_commands_strings[command_idx][check_idx] == command[check_idx]) {
             check_idx++;
         }
         if (command[check_idx] == 0 && shell_commands_strings[command_idx][check_idx] == 0) {
@@ -176,7 +189,7 @@ void shell_step() {
         buffer_idx = 0;
 
         if (result == -1) {
-            terminal_writestring("No such command\n");
+            print("No such command\n");
         }
     } else if (curr_char == 0x08) {
         if (buffer_idx != 0) {

kernel/tests/tests.c

@@ -0,0 +1,91 @@
+#ifndef TESTS_TESTS_C
+#define TESTS_TESTS_C
+
+#define TESTS_ENABLED
+#ifdef TESTS_ENABLED
+
+
+#define mu_assert(message, test) do { if (!(test)) return message; } while (0)
+#define mu_run_test(test) do { char *message = test(); tests_run++; \
+                                if (message) return message; } while (0)
+extern int tests_run;
+
+#include "../memory.c"
+#include <stddef.h>
+
+
+int tests_run = 0;
+
+
+static char *test_memory() {
+
+    ll_node *ll_head = __new_node();
+    ll_head->data = malloc(sizeof(size_t) * 5000);
+    ll_head->used = true;
+    ll_head->size = 1;
+    void *ptr0 = __alloc(ll_head, 5);
+    void *ptr1 = __alloc(ll_head, 5);
+    void *ptr4 = __alloc(ll_head, 5);
+    print(ll_head);
+    mu_assert("Error: chain should be complete at 1", ll_head->next != NULL);
+    mu_assert("Error: chain should be complete at 2", ll_head->next->next != NULL);
+    mu_assert("Error: chain should be complete at 3", ll_head->next->next->next != NULL);
+    mu_assert("Error: chain should be complete at 4", ll_head->next->next->next->next == NULL);
+
+    ll_node *current = ll_head;
+    while (current->next != NULL) {
+        current = current->next;
+
+        mu_assert("Error: block should have size 5", current->size == 5);
+        mu_assert("Error: block should be in use", current->used == true);
+    }
+
+    __free(ll_head, ptr1);
+    mu_assert("", ll_head->next->used == true);
+    mu_assert("", ll_head->next->next->used == false);
+    mu_assert("", ll_head->next->next->next->used == true);
+
+    printf("Alloc 3 bytes\n");
+    void *ptr2 = __alloc(ll_head, 3);
+    print(ll_head);
+
+    printf("Alloc 3 bytes\n");
+    __alloc(ll_head, 3);
+    print(ll_head);
+
+    printf("Alloc 2 bytes\n");
+    void *ptr3 = __alloc(ll_head, 2);
+    print(ll_head);
+
+    __free(ll_head, ptr2);
+    print(ll_head);
+    __free(ll_head, ptr4);
+    print(ll_head);
+    __free(ll_head, ptr3);
+    print(ll_head);
+
+    __free(ll_head, ptr0);
+    print(ll_head);
+    return 0;
+}
+
+static char *all_tests() {
+    mu_run_test(test_memory);
+    return 0;
+}
+//
+//int main(int argc, char **argv) {
+//    char *result = all_tests();
+//    if (result != 0) {
+//        printf("%s\n", result);
+//    } else {
+//        printf("ALL TESTS PASSED\n");
+//    }
+//    printf("Tests run: %d\n", tests_run);
+//
+//    return result != 0;
+//}
+
+#endif // TESTS_ENABLED
+
+#endif // TESTS_TESTS_C

kernel/util/printer.c

@@ -0,0 +1,72 @@
+#ifndef UTIL_PRINTER_C
+#define UTIL_PRINTER_C
+
+#include <stdarg.h>
+
+#include "../terminal.c"
+
+/**
+ * fmt is a string with specifiers where variables can be inserted.
+ *
+ * ex: ("Hello %s", "world") -> "Hello world"
+ *
+ * Specifiers are
+ *   - %c: character
+ *   - %d: digit (integer)
+ *   - %x: hexadecimal value. Can be used to print pointers to
+ *   - %b: binary value. Digits with base 2
+ * @param fmt Formatter string
+ * @param ... Variable amount of arguments to be inserted
+ */
+void print(const char *fmt, ...) {
+    const char *p;
+    va_list argp;
+    int i;
+    char *s;
+    char fmtbuf[256];
+
+    va_start(argp, fmt);
+
+    for (p = fmt; *p != '\0'; p++)
+        if (*p != '%') {
+            terminal_putchar(*p);
+        } else {
+            switch (*++p) {
+                case 'c':
+                    i = va_arg(argp, int);
+
+                    terminal_putchar((char) i);
+                    break;
+                case 'd':
+                    i = va_arg(argp, int);
+                    s = itoa(i, fmtbuf, 10);
+                    terminal_writestring(s);
+                    break;
+                case 's':
+                    s = va_arg(argp, char *);
+                    terminal_writestring(s);
+                    break;
+                case 'x':
+                    terminal_writestring("0x");
+
+                    i = va_arg(argp, int);
+                    s = itoa(i, fmtbuf, 16);
+                    terminal_writestring(s);
+                    break;
+                case 'b':
+                    terminal_writestring("0b");
+
+                    i = va_arg(argp, int);
+                    s = itoa(i, fmtbuf, 2);
+                    terminal_writestring(s);
+                    break;
+                case '%':
+                    terminal_putchar('%');
+                    break;
+            }
+        }
+
+    va_end(argp);
+}
+
+#endif //UTIL_PRINTER_C