C/C++ error

#ifndef _I386_PAGE_H
#define _I386_PAGE_H
/* PAGE_SHIFT determines the page size */
#define PAGE_SHIFT 12
#define PAGE_SIZE (1UL << PAGE_SHIFT)
#define PAGE_MASK (~(PAGE_SIZE-1))
#define LARGE_PAGE_MASK (~(LARGE_PAGE_SIZE-1))
#define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)
#ifdef __KERNEL__
#ifndef __ASSEMBLY__
#include <linux/config.h>

#ifdef CONFIG_X86_USE_3DNOW

#include <asm/mmx.h>

#define clear_page(page) mmx_clear_page((void *)(page))
#define copy_page(to,from) mmx_copy_page(to,from)

#else

/*
* On older X86 processors it‘s not a win to use MMX here it seems.
* Maybe the K6-III ?
*/

#define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
#define copy_page(to,from) memcpy((void *)(to), (void *)(from), PAGE_SIZE)

#endif

#define clear_user_page(page, vaddr, pg) clear_page(page)
#define copy_user_page(to, from, vaddr, pg) copy_page(to, from)

/*
* These are used to make use of C type-checking..
*/
#ifdef CONFIG_X86_PAE
typedef struct { unsigned long pte_low, pte_high; } pte_t;
typedef struct { unsigned long long pmd; } pmd_t;
typedef struct { unsigned long long pgd; } pgd_t;
#define pte_val(x) ((x).pte_low | ((unsigned long long)(x).pte_high << 32))
#define HPAGE_SHIFT 21
#else
typedef struct { unsigned long pte_low; } pte_t;
typedef struct { unsigned long pmd; } pmd_t;
typedef struct { unsigned long pgd; } pgd_t;
#define boot_pte_t pte_t /* or would you rather have a typedef */
#define pte_val(x) ((x).pte_low)
#define HPAGE_SHIFT 22
#endif
#define PTE_MASK PAGE_MASK

#ifdef CONFIG_HUGETLB_PAGE
#define HPAGE_SIZE ((1UL) << HPAGE_SHIFT)
#define HPAGE_MASK (~(HPAGE_SIZE - 1))
#define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT)
#endif

typedef struct { unsigned long pgprot; } pgprot_t;

#define pmd_val(x) ((x).pmd)
#define pgd_val(x) ((x).pgd)
#define pgprot_val(x) ((x).pgprot)

#define __pte(x) ((pte_t) { (x) } )
#define __pmd(x) ((pmd_t) { (x) } )
#define __pgd(x) ((pgd_t) { (x) } )
#define __pgprot(x) ((pgprot_t) { (x) } )

#endif /* !__ASSEMBLY__ */

/* to align the pointer to the (next) page boundary */
#define PAGE_ALIGN(addr) (((addr)+PAGE_SIZE-1)&PAGE_MASK)

/*
* This handles the memory map.. We could make this a config
* option, but too many people screw it up, and too few need
* it.
*
* A __PAGE_OFFSET of 0xC0000000 means that the kernel has
* a virtual address space of one gigabyte, which limits the
* amount of physical memory you can use to about 950MB. 
*
* If you want more physical memory than this then see the CONFIG_HIGHMEM4G
* and CONFIG_HIGHMEM64G options in the kernel configuration.
*/

/*
* This much address space is reserved for vmalloc() and iomap()
* as well as fixmap mappings.
*/
#define __VMALLOC_RESERVE (128 << 20)

#ifndef __ASSEMBLY__

/* Pure 2^n version of get_order */
static __inline__ int get_order(unsigned long size)
{
int order;

size = (size-1) >> (PAGE_SHIFT-1);
order = -1;
do {
   size >>= 1;
   order++;
} while (size);
return order;
}

#endif /* __ASSEMBLY__ */

#ifdef __ASSEMBLY__
#define __PAGE_OFFSET   (0xC0000000)
#else
#define __PAGE_OFFSET   (0xC0000000UL)
#endif

#define PAGE_OFFSET   ((unsigned long)__PAGE_OFFSET)
#define VMALLOC_RESERVE   ((unsigned long)__VMALLOC_RESERVE)
#define MAXMEM    (-__PAGE_OFFSET-__VMALLOC_RESERVE)
#define __pa(x)    ((unsigned long)(x)-PAGE_OFFSET)
#define __va(x)    ((void *)((unsigned long)(x)+PAGE_OFFSET))
#define pfn_to_kaddr(pfn)      __va((pfn) << PAGE_SHIFT)
#ifndef CONFIG_DISCONTIGMEM
#define pfn_to_page(pfn) (mem_map + (pfn))
#define page_to_pfn(page) ((unsigned long)((page) - mem_map))
#define pfn_valid(pfn)   ((pfn) < max_mapnr)
#endif /* !CONFIG_DISCONTIGMEM */
#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)

#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)

#define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | VM_EXEC | \
     VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)

#endif /* __KERNEL__ */

#endif /* _I386_PAGE_H */