使用一维字符数组翻转图像

I have the data of an image loaded into memory as a one dimensional array. Since I'm trying to use OpenGL to draw it, and since it reads from the bottom up, I want to try and flip the elements of the array before they're sent to OpenGL. Maybe there's a way to tell OpenGL to read from the top to the bottom? Anyways, I tried using a few methods of sorting arrays and they also flip the image horizontally, which is very much like the original problem. So can I flip the data only one way?I have the data of an image loaded into memory