fox32rom: Move disk booting routines to a separate file

boot.asm

@@ -0,0 +1,58 @@
+; disk booting routines
+; these are only used during booting, they are not exposed via the jump table
+
+; read disk 0 and attempt to figure out what type of disk it is, and load the correct binary into memory
+; currently this only supports booting raw binaries
+; inputs:
+; r0: disk size (bytes)
+; outputs:
+; none (doesn't return)
+start_boot_process:
+    ; 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
+start_boot_process_sector_loop:
+    out r3, r0         ; read the current sector into the sector buffer
+    mov r1, 0          ; byte counter
+start_boot_process_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 start_boot_process_byte_loop
+    loop start_boot_process_sector_loop
+
+    ; done loading !!!
+    ; now clean up and jump to the loaded binary
+    call boot_cleanup
+    jmp 0x00000800
+
+; clean up the system's state before jumping to the loaded binary
+; inputs:
+; none
+; outputs:
+; none
+boot_cleanup:
+    ; clear the background
+    mov r0, 0xFF000000
+    call fill_background
+
+    ; disable the menu bar
+    mov r0, 0x8000031E
+    out r0, 0
+
+    ret

main.asm

@@ -134,7 +134,7 @@ event_loop:
     ; 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
+    ifnz call start_boot_process
 
     jmp event_loop
 
@@ -161,41 +161,8 @@ mount_boot_disk:
     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 "boot.asm"
     #include "background.asm"
     #include "overlay.asm"
     #include "menu.asm"