sh: Use the "current" disk id

applications/sh/commands/dir.asm

@@ -6,8 +6,9 @@ shell_dir_command:
     mov r0, shell_dir_command_header_string
     call print_str_to_terminal
 
+    call get_current_disk_id
+    mov r1, r0
     mov r0, shell_dir_command_list_buffer
-    movz.8 r1, [shell_current_disk]
     call ryfs_get_file_list
     cmp r0, 0
     ifz ret
@@ -52,9 +53,10 @@ shell_dir_command_loop:
     call print_character_to_terminal
 
     ; get and print the file size
+    call get_current_disk_id
+    mov r1, r0
     mov r0, shell_dir_command_list_buffer
     add r0, r3
-    movz.8 r1, [shell_current_disk]
     mov r2, shell_dir_command_temp_file_struct
     call open
     cmp r0, 0

applications/sh/commands/disk.asm

@@ -10,17 +10,22 @@ shell_disk_command:
     ; r0: disk ID
 
     ; check if it's in range
-    cmp r0, 3
+    cmp r0, 4
     ifgt jmp shell_disk_command_out_of_range
+    ifz jmp shell_disk_command_is_disk
 
+    call is_romdisk_available
+    ifnz ret
+    jmp shell_disk_command_is_romdisk
+shell_disk_command_is_disk:
     ; OR it with the IO port to get the current insert state of a disk
     or r0, 0x80001000
     in r1, r0
     cmp r1, 0
     ifz ret
-
+shell_disk_command_is_romdisk:
     ; set the current disk ID
-    mov.8 [shell_current_disk], r0
+    call set_current_disk_id
 
     ret
 

applications/sh/commands/type.asm

@@ -31,8 +31,9 @@ shell_type_command:
     mov.8 [r1], 0
 
     ; open the file
+    call get_current_disk_id
+    mov r1, r0
     mov r0, shell_type_command_file
-    movz.8 r1, [shell_current_disk]
     mov r2, shell_type_command_file_struct
     call open
     cmp r0, 0

applications/sh/launch.asm

@@ -35,8 +35,9 @@ launch_fxf_name_loop:
     loop launch_fxf_name_loop
 launch_fxf_name_loop_done:
     ; open the file
+    call get_current_disk_id
+    mov r1, r0
     mov r0, launch_fxf_name
-    movz.8 r1, [shell_current_disk]
     mov r2, launch_fxf_struct
     call open
     cmp r0, 0

applications/sh/main.asm

@@ -95,7 +95,7 @@ shell_key_down_backspace:
     ret
 
 shell_print_prompt:
-    movz.8 r0, [shell_current_disk]
+    call get_current_disk_id
     add r0, '0'
     call print_character_to_terminal
     mov r0, shell_prompt
@@ -309,8 +309,6 @@ shell_text_buf_top:
 shell_text_buf_ptr:    data.32 0 ; pointer to the current input character
 shell_args_ptr:        data.32 0 ; pointer to the beginning of the command arguments
 
-shell_current_disk: data.8 0
-
 shell_prompt: data.str "> " data.8 CURSOR data.8 0
 
 shell_terminal_stream_struct_ptr: data.32 0