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#include <hardware.h>
.module crt0
.globl _main
.area _HEADER (ABS)
.org 0x0000
start:
xor a
ld i, a
ld sp, #0x0000
di
;; Init PIO and check for KEY2
ld a, #PIO_MODE_3
out (PORT_B_CTRL), a
ld a, #0x7F
out (PORT_B_CTRL), a
in a, (PORT_B_DATA)
and #0x02 ; is KEY2 pressed? If so, start booloader
jr NZ, main
;; Load payload (bootloader)
ld HL, #0x7000
ld DE, #0x8000
ld BC, #0x1000
ldir
;; Start bootloader
jp 0x8000
main:
call gsinit
call _main
1$:
halt
jr 1$
;; Ordering of segments for the linker.
.area _HOME
.area _CODE
.area _INITIALIZER
.area _GSINIT
.area _GSFINAL
.area _DATA
.area _INITIALIZED
.area _BSEG
.area _BSS
.area _HEAP
.area _CODE
.area _GSINIT
gsinit:
;; Default-initialized global variables.
ld bc, #l__DATA
ld a, b
or a, c
jr Z, zeroed_data
ld hl, #s__DATA
ld (hl), #0x00
dec bc
ld a, b
or a, c
jr Z, zeroed_data
ld e, l
ld d, h
inc de
ldir
zeroed_data:
;; Explicitly initialized global variables.
ld bc, #l__INITIALIZER
ld a, b
or a, c
jr Z, gsinit_next
ld de, #s__INITIALIZED
ld hl, #s__INITIALIZER
ldir
gsinit_next:
.area _GSFINAL
ret
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