M include/cedos/mm/memory.h → include/cedos/mm/memory.h

@@ -8,6 +8,10 @@ #include <stdint.h>
 
 typedef uint32_t size_t;
 
+#define NULL (void*)(0)
+
+int malloc_init();
+
 /*!
  * Allocates a block of \p size bytes of memory. (KERNEL MODE)
  * \param size Size in bytes of the requested block of memory.

M src/kernel/main.c → src/kernel/main.c

@@ -7,6 +7,7 @@ #include "cedos/sched/sched.h"
 #include "cedos/sched/process.h"
 
 #include "cedos/mm/paging.h"
+#include "cedos/mm/memory.h"
 
 #include "cedos/interrupts.h"
 #include "cedos/syscall.h"
@@ -48,6 +49,10 @@ printk("done.\n");
 
     printk("Setting up paging...");
     paging_init();
+    printk("done.\n");
+
+    printk("Initiallizing malloc...");
+    malloc_init();
     printk("done.\n");
 
     printk("Activating interrupts...");

M src/kernel/mm/memory.c → src/kernel/mm/memory.c

@@ -1,12 +1,49 @@
 #include "cedos/mm/memory.h"
 
+struct memblock {
+    struct memblock *next;
+    int size;
+};
+
+struct memblock *malloc_first, *malloc_last, *malloc_next_free;
+
+int malloc_init() {
+    uint32_t mem_start = 0xC0400000u;
+    uint32_t mem_end = 0xC0800000u;
+
+    malloc_first = (struct memblock*)(mem_start);
+    malloc_last = (struct memblock*)(mem_end - sizeof(struct memblock));
+    malloc_next_free = malloc_first;
+
+    malloc_first->size = 0;
+    malloc_first->next = malloc_last;
+
+    malloc_last->size = 0;
+    malloc_last->next = NULL;
+}
+
 /*!
  * Allocates a block of \p size bytes of memory. (KERNEL MODE)
  * \param size Size in bytes of the requested block of memory.
  * \return Memory address to the new memory block
  */
 void* os_kernel_malloc(size_t size) {
-    return (void*)0;
+    uint32_t addr = (uint32_t)(malloc_next_free);
+
+    // TODO: test if memory block is large enough
+    addr += sizeof(struct memblock);
+    addr += size;
+
+    struct memblock *new_block = (struct memblock*)(addr);
+    new_block->next = malloc_next_free->next;
+    
+    // TODO: maybe not big enough?
+    new_block->size = 0;
+
+    malloc_next_free->next = new_block;
+    malloc_next_free->size = size;
+
+    return (void*)(&malloc_next_free[1]);
 }
 
 /*!