KISS_bootloader/bootsector.dasm at master · FrOSt-Foundation/KISS_bootloader · GitHub

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; Minimal boot sector
; You can just slap it at the beginning of you program and change the corresponding values
;
; A contains the floppy ID
; B contains the device list ID

; in sectors, not including the bootsector (TO CHANGE)
:PROGRAM_SIZE .dat 0

#define COPY_LOCATION 0xF000
#define FLOPPY_STATE_BUSY 3
#define SECTOR_SIZE 0x200

set I, copy
set J, COPY_LOCATION
set C, memcpy - copy
set PUSH, COPY_LOCATION
set PC, memcpy

:copy
set PUSH, B
set PUSH, A
set Y, 0
set Z, [PROGRAM_SIZE]
add Z, 1
set X, 1
set A, 2
hwi PEEK
set A, 0
hwi PEEK
ife B, FLOPPY_STATE_BUSY
    sub PC, 3
add X, 1
add Y, SECTOR_SIZE
ifg X, Z
    add PC, 1
sub PC, 10
set A, POP
set B, POP
set C, 0
set X, 0
set Y, 0
set Z, 0
set EX, 0
set SP, 0
set PC, 0

; I -> from
; J -> to
; C -> size
:memcpy
ife C, 0
    set PC, POP
sti [J], [I]
sub C, 1
sub PC, 5


.org 0x1F2, 0
; reserved for future use
.dat 0 0 0
; name, needs to reserve 10 u16 in total (TO CHANGE)
.dat "cFrOSt" 0 0 0

; magic word to be found as a bootsector by the bootloader
.dat 0x55AA