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

@@ -4,6 +4,8 @@ */
 #ifndef PAGE_ALLOCATOR_H
 #define PAGE_ALLOCATOR_H
 
+#include <stdint.h>
+
 /*!
  * Returns a free page and marks it as used.
  * \return Address of the first byte on the page or NULL if no page was allocated.
@@ -15,5 +17,7 @@ * Adds a previously allocated page as free.
  * \param page_addr Pointer to any byte within the page to be freed.
  */
 void mark_as_free(void* page_addr);
+
+uint32_t mem_usage(void);
 
 #endif

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

@@ -1,12 +1,17 @@
 #include "cedos/mm/page_allocator.h"
 #include "cedos/mm/paging.h"
+#include "cedos/core.h"
 
-uint8_t* first_free = (uint8_t*)0x00200000;
+uint8_t* first_free = (uint8_t*)0x00500000;
 
 void* get_free_page() {
     void* res = first_free;
     first_free += PAGE_SIZE;
     return res;
+}
+
+uint32_t mem_usage(void) {
+    return (uint32_t)(first_free);
 }
 
 void mark_as_free(void* page_addr) {

M src/kernel/syscall.c → src/kernel/syscall.c

@@ -4,6 +4,7 @@ #include "cedos/sched/sched.h"
 #include "cedos/file.h"
 #include "cedos/drivers/graphics.h"
 #include "cedos/time.h"
+#include "cedos/mm/page_allocator.h"
 
 void test(uint32_t ebx, uint32_t ecx, uint32_t edx) {
     printk("SYSCALL 0x01: EBX=%i ECX=%X EDX=%X\n", ebx, ecx, edx);
@@ -23,6 +24,7 @@ file_dir_next,
         file_lseek,
         file_tell,
         time_get_ticks,
+        mem_usage
     };
 
 extern void syscall_interrupt(void);

M src/libcedos/cedos.c → src/libcedos/cedos.c

@@ -90,3 +90,8 @@ interrupt(0x30, res, 12, 0, 0, 0);
     return res;
 }
 
+uint32_t sc_mem_usage(void) {
+    volatile int res = 0;
+    interrupt(0x30, res, 13, 0, 0, 0);
+    return res;
+}

M src/libcedos/include/cedos.h → src/libcedos/include/cedos.h

@@ -25,5 +25,7 @@
 int dir_next(int fd, int index, char *fname_buffer);
 
 int sc_time_get_ticks(void);
+uint32_t sc_mem_usage(void);
+
 
 #endif

A src/shell/memusage.c

@@ -0,0 +1,9 @@
+#include "cedos.h"
+#include "stdio.h"
+
+#include <stdint.h>
+
+void main(char *args) {
+    uint32_t memusage = sc_mem_usage();
+    printf("%i KB\n", memusage / 1000);
+}