/**
 * @file mem.c
 * Memory handling syscall implementations.
 */

#include <apos/uapi.h>
#include <apos/utils.h>
#include <apos/vmem.h>
#include <apos/dmem.h>

SYSCALL_DEFINE2(req_mem)(sys_arg_t size, sys_arg_t flags)
{
	/* get current effective process */
	struct tcb *r = cur_proc();
	return (struct sys_ret){ OK, alloc_uvmem(r, size, flags) };
}

SYSCALL_DEFINE3(req_fixmem)(sys_arg_t start, sys_arg_t size, sys_arg_t flags)
{
	struct tcb *r = cur_proc();
	/* should probably check if the allocation succeeded...? \todo */
	return (struct sys_ret){ OK, alloc_fixed_uvmem(r, start, size, flags) };
}

SYSCALL_DEFINE1(free_mem)(sys_arg_t start)
{
	struct tcb *r = cur_proc();
	vm_t vm_start = (vm_t)start;

	if (vm_start > __pre_top && vm_start < __post_base)
		free_uvmem(r, vm_start);
	else
		free_devmem(r, vm_start);

	return (struct sys_ret){ OK, 0 };
}

SYSCALL_DEFINE3(req_pmem)(sys_arg_t paddr, sys_arg_t size, sys_arg_t flags)
{
	/* this will require some pondering, but essentially this syscall should
	 * only be used for device access, so any addresses requested should be
	 * outside the RAM area, and I'll probably have to implement some method
	 * that keeps track of used regions outside of RAM. We'll see.
	 */
	struct tcb *r = cur_proc();
	return (struct sys_ret){ OK, alloc_devmem(r, paddr, size, flags) };
}

SYSCALL_DEFINE2(req_sharedmem)(sys_arg_t size, sys_arg_t flags)
{
	/* \todo: check that requester is server */
	struct tcb *t = cur_proc();
	vm_t start = 0;
	if ((start = alloc_shared_uvmem(t, size, flags)))
		return (struct sys_ret){ ERR_OOMEM, 0 };

	return (struct sys_ret){ OK, start };
}

/* add a syscall like ref_sharedmem that adds a reference to an existing shared
 * memory region to a new tid? */
SYSCALL_DEFINE3(ref_sharedmem)(sys_arg_t tid, sys_arg_t va, sys_arg_t flags)
{
	struct tcb *t1 = cur_tcb();
	struct tcb *t2 = get_tcb(tid);
	vm_t start = 0;
	if ((start = ref_shared_uvmem(t1, t2, va, flags)))
		return (struct sys_ret){ ERR_OOMEM, 0 };

	return (struct sys_ret){ OK, start };
}

/** \todo add some way to specify who gets to access the shared memory? */