Lesson 6 Screen01 InitialiseFrameBuffer function should use r4 to store fbInfoAddr

[yeqingyan]

In lesson 6, the InitialiseFrameBuffer function using r3 to store fbInfoAddr,

fbInfoAddr .req r3

but then r3 will be used by function MailboxRead/MailboxWrite, that make the function InitialiseFrameBuffer return the wrong pointer:

mov result,fbInfoAddr
pop {pc}
.unreq result
.unreq fbInfoAddr

I followed the code in lesson 6, the image will not show due to this reason. The solution code fixed it by using r4 to store the fbInfoAddr, and push/pop r4 with pc register.

[cmurphy]

++ I ran into this too.