fox32os/kernel/main.asm

153 lines
3.8 KiB
NASM

; fox32os kernel
org 0x00000800
const FOX32OS_VERSION_MAJOR: 0
const FOX32OS_VERSION_MINOR: 1
const FOX32OS_VERSION_PATCH: 0
const BACKGROUND_COLOR: 0xFF674764
const TEXT_COLOR: 0xFFFFFFFF
const STARTUP_TASK_LOAD_ADDRESS: 0x03000000
jmp entry
jump_table:
; system jump table
org.pad 0x00000810
data.32 get_os_version
; FXF jump table
org.pad 0x00000820
data.32 parse_fxf_binary
; task jump table
org.pad 0x00000830
data.32 new_task
data.32 yield_task
data.32 end_current_task
; memory jump table
org.pad 0x00000840
data.32 allocate_memory
; initialization code
entry:
; clear the background
mov r0, BACKGROUND_COLOR
call fill_background
draw_startup_text:
mov r0, startup_str
mov r1, 16
mov r2, 464
mov r3, TEXT_COLOR
mov r4, 0x00000000
mov r10, FOX32OS_VERSION_MAJOR
mov r11, FOX32OS_VERSION_MINOR
mov r12, FOX32OS_VERSION_PATCH
call draw_format_str_to_background
; open startup.cfg
mov r0, startup_file
mov r1, 0
mov r2, startup_file_struct
call ryfs_open
cmp r0, 0
ifz jmp boot_disk_1
; load the first 11 bytes of startup.cfg, overwriting the "startup cfg" string
mov r0, 11
mov r1, startup_file_struct
mov r2, startup_file
call ryfs_read
; open the actual startup file
mov r0, startup_file
mov r1, 0
mov r2, startup_file_struct
call ryfs_open
cmp r0, 0
ifz jmp boot_disk_1
; read the startup file into memory starting at STARTUP_TASK_LOAD_ADDRESS
mov r0, startup_file_struct
mov r1, STARTUP_TASK_LOAD_ADDRESS
call ryfs_read_whole_file
; relocate and execute it as a new task
run_startup_task:
mov r0, STARTUP_TASK_LOAD_ADDRESS
call parse_fxf_binary
mov r1, r0
mov r0, 0
mov r2, rsp
call new_task
; when the startup file yields for the first time, we'll end up back here
; jump back to it without adding this "task" (not really a task) into the queue
; end_current_task_no_mark is used specifically because it doesn't mark the current task (still set to 0) as unused
; this does not return
call end_current_task_no_mark
; if startup.cfg is invalid, try loading the raw contents of disk 1 as an FXF binary
; if disk 1 is not inserted, then fail
boot_disk_1:
; check if a disk is inserted as disk 1
in r31, 0x80001001
cmp r31, 0
ifz jmp startup_error
; a disk is inserted, load it!!
div r31, 512
inc r31
mov r0, 0 ; sector counter
mov r2, STARTUP_TASK_LOAD_ADDRESS ; destination pointer
mov r3, 0x80003001 ; command to read a sector from disk 01 into memory
mov r4, 0x80002000 ; command to set the location of the buffer
boot_disk_1_loop:
out r4, r2 ; set the memory buffer location
out r3, r0 ; read the current sector into memory
inc r0 ; increment sector counter
add r2, 512 ; increment the destination pointer
loop boot_disk_1_loop
jmp run_startup_task
startup_error:
mov r0, BACKGROUND_COLOR
call fill_background
mov r0, startup_error_str
mov r1, 16
mov r2, 464
mov r3, TEXT_COLOR
mov r4, 0x00000000
mov r10, FOX32OS_VERSION_MAJOR
mov r11, FOX32OS_VERSION_MINOR
mov r12, FOX32OS_VERSION_PATCH
call draw_format_str_to_background
rjmp 0
get_os_version:
mov r0, FOX32OS_VERSION_MAJOR
mov r1, FOX32OS_VERSION_MINOR
mov r2, FOX32OS_VERSION_PATCH
ret
#include "allocator.asm"
#include "fxf/fxf.asm"
#include "task.asm"
startup_str: data.str "fox32 - OS version %u.%u.%u" data.8 0
startup_error_str: data.str "fox32 - OS version %u.%u.%u - startup.cfg is invalid!" data.8 0
startup_file: data.str "startup cfg"
startup_file_struct: data.32 0 data.32 0
#include "../../fox32rom/fox32rom.def"
kernel_bottom: