Add base code for custom stack length

Makefile

@@ -5,7 +5,7 @@ CPU = -mcpu=cortex-m4
 THUMB = -mthumb
 
 LDFLAGS = -T linker.ld
-CFLAGS = $(CPU) $(THUMB)
+CFLAGS = $(CPU) $(THUMB) -I libc/
 
 QEMU = qemu-system-arm
 BOARD = netduino2
@@ -13,7 +13,7 @@ BOARD = netduino2
 # Output file
 TARGET = main.elf
 # Source files
-SRCS = os/main.c os/process.c os/scheduler.c os/alloc.c tasks/library.c tasks/tasks.c
+SRCS = os/main.c os/process.c os/scheduler.c os/alloc.c libc/library.c tasks/tasks.c
 # Object files
 OBJS = $(SRCS:.c=.o)
 

os/process.c

@@ -1,15 +1,23 @@
 #include "process.h"
 #include "alloc.h"
+#include <stdint.h>
 
 void create_process_table(ProcessTable **table) {
     *table = malloc(sizeof(ProcessTable));
     (*table)->entries = 0;
 }
 
+ProcessStack* create_stack(size_t size) {
+    ProcessStack* stack = malloc(sizeof(ProcessStack) + size*sizeof(uint32_t));
+    stack->stack_size = size;
+    return stack;
+}
+
 int create_process(ProcessTable *table, void *entrypoint) {
     if (table->entries>=MAX_PROCESS) return 1;
 
     Process *pentry = &table->process_list[table->entries++];
     pentry->entrypoint = entrypoint;
+    pentry->stack = create_stack(STACK_SIZE);
     return 0;
 }

os/process.h

@@ -1,3 +1,4 @@
+#include <stddef.h>
 #ifndef PROCESS_H
 #include <stdint.h>
 
@@ -7,9 +8,14 @@
 #define STACK_SIZE 32
 #define STACK_START(stack)  (&stack[STACK_SIZE-1])
 
+typedef struct {
+    uint32_t stack_size;
+    uint32_t stack[];
+} ProcessStack;
+
 typedef struct {
     int (*entrypoint)();
-    uint32_t stack[STACK_SIZE];
+    ProcessStack* stack;
 } Process;
 
 typedef struct {
@@ -19,5 +25,7 @@ typedef struct {
 
 void create_process_table(ProcessTable **table);
 
+ProcessStack* create_stack(size_t size);
+
 int create_process(ProcessTable *table, void *entrypoint);
 #endif