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fox32rom: Add support for booting a raw binary from a disk

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ry755 2022-01-30 00:57:54 -08:00 committed by Ry
parent b8195a079d
commit ce2a571369
1 changed files with 58 additions and 9 deletions
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67
rom.asm
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@ -110,7 +110,8 @@ draw_startup_text:
ise
event_loop:
call wait_for_event
halt
call pop_event
; was the mouse clicked?
cmp r0, mouse_click_event_type
@ -129,6 +130,12 @@ event_loop:
cmp r0, submenu_click_event_type
ifz call submenu_click_event
; check if a disk is mounted as disk 0
; if port 0x8000100n returns a non-zero value, then a disk is mounted as disk n
in r0, 0x80001000
cmp r0, 0
ifnz call load_boot_disk
jmp event_loop
submenu_click_event:
@ -138,13 +145,56 @@ submenu_click_event:
cmp r3, 0
;
; mount disk
cmp r3, 1
ifz jmp mount_boot_disk
; halt
cmp r3, 3
cmp r3, 2
ifz icl
ifz halt
ret
mount_boot_disk:
mov r0, 0x80001000
out r0, 0
ret
load_boot_disk:
; in the future, this will check the header for various different types of disk types
; but for now, just assume the user mounted a raw binary
; load it to 0x00000800 (immediately after the interrupt vectors) and jump
; r0 contains the size of the disk in bytes
; divide the size by 512 and add 1 to get the size in sectors
div r0, 512
inc r0
mov r31, r0
mov r0, 0 ; sector counter
mov r2, 0x00000800 ; destination pointer
mov r3, 0x80003000 ; command to read a sector from disk 0 into the sector buffer
mov r4, 0x80002000 ; command to read a byte from the sector buffer
load_boot_disk_sector_loop:
out r3, r0 ; read the current sector into the sector buffer
mov r1, 0 ; byte counter
load_boot_disk_byte_loop:
mov r5, r4
or r5, r1 ; or the byte read command with the current byte counter
in r5, r5 ; read the current byte into r5
mov.8 [r2], r5 ; write the byte
inc r2 ; increment the destination pointer
inc r1 ; increment the byte counter
cmp r1, 512
ifnz jmp load_boot_disk_byte_loop
loop load_boot_disk_sector_loop
; done loading !!!
; now jump to the loaded binary
; TODO: clear the background, disable the menu bar, etc
jmp 0x00000800
; code
#include "background.asm"
#include "overlay.asm"
@ -227,14 +277,13 @@ menu_items_root:
data.8 1 ; number of submenus
data.32 menu_items_system_list data.32 menu_items_system_name ; pointer to submenu list, pointer to submenu name
menu_items_system_name:
data.8 6 data.str "System" data.8 0x00 ; text length, text, null-terminator
data.8 6 data.str "System" data.8 0x00 ; text length, text, null-terminator
menu_items_system_list:
data.8 4 ; number of items
data.8 22 ; submenu width (usually longest item + 2)
data.8 5 data.str "About" data.8 0x00 ; text length, text, null-terminator
data.8 20 data.str "Mount Floppy Disk..." data.8 0x00 ; text length, text, null-terminator
data.8 18 data.str "Mount Hard Disk..." data.8 0x00 ; text length, text, null-terminator
data.8 4 data.str "Halt" data.8 0x00 ; text length, text, null-terminator
data.8 3 ; number of items
data.8 12 ; submenu width (usually longest item + 2)
data.8 5 data.str "About" data.8 0x00 ; text length, text, null-terminator
data.8 10 data.str "Mount Disk" data.8 0x00 ; text length, text, null-terminator
data.8 4 data.str "Halt" data.8 0x00 ; text length, text, null-terminator
; pad out to 32 MiB
org.pad 0xF2000000