Gelthor
46abf8d893
Added support for global variables. This requires including `start.asm` as the first code. This includes a `jmp` to 0x100 for user code, and a magic number that modules can check to verify th the user has correctly reserved the space. The magic number is 0xb301534c: * This has the high bit set so is not a valid instruction * On builds that ignore the high bit this decodes to `nor zr, zr, 0x534c` a no-op. * The immediate is "SL" for standardl ibrary. Due to a bug start pads with U... 0, instead of @addr. `start.asm` also initialises `sp` so it start just below the 64KiB LUT memory alocation. Added some error codes for the upcoming graphics module.
19 lines
378 B
NASM
Executable File
19 lines
378 B
NASM
Executable File
;@0 ; Reserve space for globals
|
|
|
|
; First initialise the stack pointer
|
|
nor sp, zr, 0xffff
|
|
; Jump over the globals to user code
|
|
jmp 0x100
|
|
|
|
U32 0 ; 4 bytes
|
|
|
|
; MAGIC_VALUE
|
|
;@0x0c
|
|
U32 0xb301534c
|
|
|
|
; Pad with zeroes since the @addr feature is currently broken.
|
|
; * https://discord.com/channels/828292123936948244/1545010596246847568
|
|
;
|
|
U1920 0 ; 240 bytes
|
|
|
|
;@0x100 ; start of user code |