golang windows内存文件映射

windows下实现内存文件映射，golang实际是调用的windows api，和win32编程没神马区别。

fd, err := syscall.Open("./111.csv", syscall.GENERIC_ALL, 0)
defer syscall.Close(fd)

fsize, err := syscall.Seek(fd, 0, 2)
syscall.Seek(fd, 0, 0)
//每个block的页面个数
var pagesperblock int64 = 8192
//数据块数
var blocksize int64 = int64(syscall.Getpagesize()) * pagesperblock
var blocknum int64 = fsize / blocksize
if fsize%blocksize > 0 {
blocknum = blocknum + 1
}
hmap, err := syscall.CreateFileMapping(fd, nil, syscall.PAGE_READONLY, uint32(fsize>>32), uint32(fsize), nil)
defer syscall.CloseHandle(hmap)

var tmBgn = time.Now()

fmt.Println("blocknum=", blocknum)
var i int64
for i = 0; i < blocknum; i++ {
var datalen int32 = int32(blocksize)
if i == (blocknum - 1) {
datalen = int32(fsize % blocksize)
}
fmt.Println("datalen=", datalen)
//开始读取内存块
var currpos int64 = i * blocksize

var tmplen int = int(datalen)

addr, err := syscall.MapViewOfFile(hmap, syscall.FILE_MAP_READ, 0, uint32(currpos), uintptr(tmplen))

defer syscall.UnmapViewOfFile(addr)
//把addr变成slice
d := (*[1 << 28]byte)(unsafe.Pointer(addr))
t := d[:tmplen]
//处理数据t
}