fb: open fd in rw, don't cast mmap

Author: cobaltgit

src/common/fb.nim

@@ -21,23 +21,20 @@ const
     arr
 
 proc fbclear*() =
-  let fd = open("/dev/fb0", O_RDONLY)
+  let fd = open("/dev/fb0", O_RDWR)
   if fd < 0:
     raise newException(IOError, "Unable to open framebuffer")
 
   defer: discard fd.close()
 
-  let fbMap = cast[ptr UncheckedArray[uint16]](
-    mmap(nil, FbSize, PROT_READ or PROT_WRITE, MAP_SHARED, fd, 0)
-  )
+  let fbMap = mmap(nil, FbSize, PROT_READ or PROT_WRITE, MAP_SHARED, fd, 0)
 
-  if fbMap == cast[ptr UncheckedArray[uint16]](MAP_FAILED):
+  if fbMap == MAP_FAILED:
     raise newException(IOError, "Unable to map framebuffer")
 
   defer: discard munmap(fbMap, FbSize)
 
   zeroMem(fbMap, FbSize)
-  
 
 proc fbscreenshot*(output: string) =
   let fbFile = open("/dev/fb0", fmRead)