Create a BMP file

Hello.
I have raw bitmap data and a PCX file (I also know the width and height of the raw data image).
I want to get the palette information from the PCX, combine it with the bitmap data and create a bmp.
Oh, it's 256 colors.

One more thing.
I opened the raw data in Photoshop and then saved the image as a bmp.
When I checked "Flip row order", the bitmap data in the created BMP was exactly the same as the raw file.
If not, the bitmap data is in a different order, so I would prefer that option (Flip row order).

Any help would be appreciated.