Add base code

os/Makefile

@@ -0,0 +1,22 @@
+CC = arm-none-eabi-gcc
+AS = arm-none-eabi-as
+LD = arm-none-eabi-ld
+CPU = -mcpu=cortex-m4
+THUMB = -mthumb
+
+LDFLAGS = -T linker.ld
+CFLAGS = -c $(CPU) $(THUMB) -g
+
+all: main.o process.o scheduler.o
+
+main.o: main.c
+	$(CC) $(CFLAGS) main.c -o main.o
+
+scheduler.o: scheduler.c
+	$(CC) $(CFLAGS) scheduler.c -o scheduler.o
+
+process.o: process.c
+	$(CC) $(CFLAGS) process.c -o process.o
+
+clean:
+	rm -f *.elf *.o *.i

os/alloc.c

@@ -0,0 +1,14 @@
+#include "alloc.h"
+#include "stdint.h"
+
+void* *first_mem_avail = (void*) 0x20000000;
+
+void init_allocator() {
+    *first_mem_avail = (void*) 0x20000000 +sizeof(void*);
+}
+
+void* malloc(size_t size) {
+    void* block = *first_mem_avail;
+    *first_mem_avail += size;
+    return block;
+}

os/alloc.h

@@ -0,0 +1,4 @@
+#include <stddef.h>
+
+void init_allocator();
+void* malloc (size_t size);

os/main.c

@@ -0,0 +1,17 @@
+#include "process.h"
+#include "scheduler.h"
+#include "alloc.h"
+
+extern int task1(void);
+extern int task2(void);
+
+int main(void) {
+    init_allocator();
+    ProcessTable *ptable;
+    create_process_table(&ptable);
+
+    create_process(ptable, task1);
+    create_process(ptable, task2);
+
+    run(ptable);
+}