heap position is now dynamically determined

link.ld

@@ -12,6 +12,7 @@ SECTIONS
         *(COMMON)
         __bss_end = .;
     }
+    __heap_base = .;
     _end = .;
 
     /DISCARD/ : { *(.comment) *(.gnu*) *(.note*) *(.eh_frame*) }

src/boot.S

@@ -24,8 +24,5 @@ _start:
     cbnz    w2, 3b
 
 4:  # Jump to main() in C
-    ldr     x0, =_start
-    ldr     x1, =0x50000
-    str     x0, [x1]
     bl      main
     b       1b

src/convert.c

@@ -47,7 +47,7 @@ char* ultoa(unsigned long number, char* string, int base)
             if(digit < 10)
                 temp[i++] = '0' + digit;
             else
-                temp[i++] = 'A' + digit;
+                temp[i++] = 'A' + digit - 10;
         }
     }
 

src/kernel.c

@@ -8,8 +8,7 @@ char* get_user_input(char* buffer);
 
 void main()
 {
-    const char* hex_chars = "0123456789ABCDEF";
+    extern long _start;
-    long int start = *(volatile long int*)0x50000;
     char buffer[1024];
 
     uart_init();
@@ -18,7 +17,7 @@ void main()
     print_clippy();
     uart_puts("Boot successful! \n");
     uart_puts("Started execution at 0x");
-    uart_puts(ultoa(start, buffer, 16));
+    uart_puts(ultoa((long)&_start, buffer, 16));
 
     for(;;)
     {

src/memory.c

@@ -15,14 +15,12 @@ struct Block
     void* data;
 };
 
-#define HEAP_BASE ((void*)0x40000000)
+extern const void* __heap_base;
-#define BLOCK_SIZE 4096
+static struct FreeBlock* head = NULL;
-#define MAGIC_NUMBER 0xDEADBEEF
-
-static struct FreeBlock* head = (struct FreeBlock*)HEAP_BASE;
 
 void heap_init()
 {
+    head = (struct FreeBlock*)__heap_base;
     head->next = head + sizeof(struct FreeBlock);
     head->size = 0;