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Fixed some typos in part12 write-up

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Adam Greenwood-Byrne 2021-03-28 17:31:03 +01:00
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part12-wgt/README.md
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@ -14,24 +14,24 @@ As I port the WGT to my OS (a.k.a. make it work on my OS), I am using the follow
* _bin/_ : for WGT binary files (fonts, sprites, bitmaps etc.)
* _controller/_ : a new Node.js BLE controller which is a little more advanced and fully emulates a 2-button mouse
* _include/_ : now contains _wgt.h_ and _wgtspr.h_ too (header files necessary for WGT code)
* _sample/_ : sample "kernels" for my OS which exercise certain WGT library functions. To build them, copy one of these (and only one at a time) to the same directory as the _Makefile_.
* _samples/_ : sample "kernels" for my OS which exercise certain WGT library functions. To build them, copy one of these (and only one at a time) to the same directory as the _Makefile_.
* _wgt/_ : the library itself. Where possible, I have stayed true to the original code, but do bear in mind it was written for the x86 architecture and we're on AArch64!
Building
--------
So... to build the first sample simply type `cp samples/wgt01.c .` from the top-level directory, and then type `make`. When you boot with the generated _kernel8.img_ you will see the screen go into 320x200 (VGA!) mode and draw a white line from corner to corner.
So... to build the first sample simply type `cp samples/wgt01.c .` from the top-level directory, and then type `make`. When you boot with the generated _kernel8.img_ you will see the screen go into 320x200 (VGA!) mode and draw a white line from corner to corner. If you do, the library is doing its stuff!
boot/boot.S changes
-------------------
We're still booting into a multicore environment (just in case we need it). There are a few significant changes to _boot/boot.S_ though. I will write more on these later, but (for now) they are:
* Enable FPU (floating-point unit) access... so we can do non-integer mathematics
* Enable FPU (floating-point unit) access so we can do non-integer mathematics
* Switch from EL3 (supervisor exception level) down to EL1 (kernel exception level), disabling the MMU all the same
* Move the addresses for the `spin_cpu` variables to accommodate a larger _boot.S_
* Implement a `get_el` function to check which exception level we're at (for debug mainly)
Work in progress!
-----------------
This part is still work in progress - and it's a *lot* of work - so keep watching this space!
This part is still work in progress - and it's a lot of work - so keep watching this space!
_In the meantime, do have a go at building some of the samples..._