Clean up - and correct detection handling of multiple active partitions

slrboot.nasm

@@ -3,7 +3,7 @@ BITS 16
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; SLRboot
 ; Bootloader for SingOS
-; version 0.2.0.3-exp
+; version 0.2.1.0-exp
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 cli
 jmp long 0x0000:start
@@ -36,34 +36,36 @@ call print      ; Call our string-printing routine
 xor bx, bx
 xor cx, cx
 mov ax, [partition_1.active_partition]
-cmp ax, 0x80
+cmp al, 0x80
 jne check_p_2
 mov bx, 0x01 ; Partion 1 active
 inc cx
 
 check_p_2:
 mov ax, [partition_2.active_partition]
-cmp ax, 0x80
+cmp al, 0x80
 jne check_p_3
 inc cx
 mov bx, 0x02 ; Partion 2 active
 
 check_p_3:
 mov ax, [partition_3.active_partition]
-cmp ax, 0x80
+cmp al, 0x80
 jne check_p_4
 inc cx
 mov bx, 0x03 ; Partion 3 active
 
 check_p_4:
-mov ax, [partition_4.active_partition]
+mov al, [partition_4.active_partition]
 cmp ax, 0x80
 jne eval_active_partion_number
 inc cx
 mov bx, 0x04 ; Partion 4 active
-
+cli
+hlt
 eval_active_partion_number: 
 cmp cx, 1
+
 je boot_partition
 ; here goes wait call, for the user to enter debug mode. 
 ; Wating for 2 seconds: 
@@ -76,18 +78,14 @@ xor ax, ax
 mov ah, 0x01 ; BIOS call to wait for key
 int 0x16
 
-
 boot_partition:
 ; IMPORTANT bx, has to hold the value 1-4 for the partiotion that wanted to be booted.  
 
-mov bx, 2
-
 mov ax, partition_1
 .loop:
     cmp bx, 1 
     je break
     add ax, 0x10
-    ;call dumpax
     dec bx
     jmp .loop
 break:
@@ -102,7 +100,6 @@ add bx, 2 ; next part
 mov ax, [bx]
 mov WORD [DAPACK.lba_addr_dw_low + 1], ax
 call dumpax
-
 mov WORD [DAPACK.blkcnt],          0x01  
 mov WORD [DAPACK.db_addr_segment], 0x0000
 mov WORD [DAPACK.db_addr_offset],  0x7c00
@@ -112,109 +109,28 @@ mov ah, 0x42                            ; READ
 mov dl, [disk_identifier] 
 int 0x13
 
+jc endcarrycheck ; An error ocurred when reading from disk. 
+
+; If no error then jump to volume boot record
+notcarry: 
 jmp long 0x0:0x7c00
 
 cli 
 hlt
 
-
+; If we did not suceed to read from disk
-%IF 0
-cli
-jmp long 0x0000:start
-
-start:
-xor ax, ax
-mov ds, ax
-mov es, ax
-mov ss, ax
-mov [disk_identifier], dl
-
-; initialize stack
-; Set up 4K stack after this bootloader
-; [Remember: Effective Address = Segment*16 + Offset]
-mov ax, 0x7C0   ; Set 'ax' equal to the location of this bootloader divided by 16
-add ax, 0x20     ; Skip over the size of the bootloader divided by 16
-mov ss, ax      ; Set 'ss' to this location (the beginning of our stack region)
-mov sp, 8192    ; Set 'ss:sp' to the top of our 8K stack
-sti
-mov si, message ; Put address of the null-terminated string to output into 'si'
-call print      ; Call our string-printing routine
-
-mov si, enter_debug_mode
-call print 
-call printCRLF
-;%IF 0
-; here goes wait call, for the user to enter debug mode. 
-; Wating for 2 seconds: 
-mov ah, 0x86   ; code for waiting interupt call
-mov cx, 0x001e ; high count of microseconds
-mov dx, 0x8480 ; low count
-int 0x15
-
-.busy_wait_for_key:
-xor ax, ax 
-mov ah, 0x01 ; BIOS call to wait for key
-int 0x16
-jnz debug_mode
-
-; entering system check: 
-mov si,  enter_system_check
-
-mov si, sys_check_ok ; Put address of the null-terminated string to output into 'si'
-call print      ; Call our string-printing routine
-
-mov si, boot_system ; Put address of the null-terminated string to output into 'si'
-call print      ; Call our string-printing routine
-
-;This goes first as to now overwrite %ah and %al.
-;mov ax, 0x0050 
-;mov es, ax                  ;Section to write into
-;mov ah, 0x2                 ;Read sectors from drive
-;mov al, 0x08                ;Number of sectors to read (31 * 512 = 15872 bytes)
-;mov ch, 0x0                 ;Low 8 bits of cylinder
-;mov cl, 0x11                ;First sector to read (bits 0-5), upper bits of cylinder (bits 6-7)
-;mov dh, 0x0                 ;Head number
-;mov dl, [disk_identifier]   ;Drive number
-;mov bx, 0x0000               ;Offset into section
-;int 0x13                    ;Low level disk services
-
-;jnc notcarry
-;mov si, error_str
-;call print
-;jmp endcarrycheck
-
-notcarry:
-;mov si, success_str
-;call print
-;call printCRLF
-
-mov ax, 0x0
-mov ds, ax
-mov ax, 89 ; lba adress
-
-jmp 0x50:0x0000   ; Jump to the kernel 
-
 endcarrycheck:  
+mov si, error_str
+call print
 cli             ; Clear the Interrupt Flag (disable external interrupts)
 hlt             ; Halt the CPU (until the next external interrupt)
 
 debug_mode: 
-mov si, .welcome_debug
+mov si, welcome_debug
 call print 
 cli             ; Clear the Interrupt Flag (disable external interrupts)
 hlt 
 
-.welcome_debug db 'This is debug mode', 0
-
-printCRLF:
-mov ah, 0xE
-mov al, 13
-int 0x10
-mov al, 10
-int 0x10
-ret
-%ENDIF
-
 ;Routine for printing a 'ax' as hex
 dumpax:
 pusha           ; save registers
@@ -237,6 +153,14 @@ loop .loop
 popa            ; restore registers
 ret
 
+printCRLF:
+mov ah, 0xE
+mov al, 13
+int 0x10
+mov al, 10
+int 0x10
+ret
+
 ; Routine for outputting string in 'si' register to screen
 print:
 mov ah, 0xE     ; Specify 'int 0x10' 'teletype output' function
@@ -251,13 +175,10 @@ jmp .printchar  ; Repeat for the next character
 ret
 
 data:
-message db 'SLRboot for SingOS! v0.2.0.3-exp',13,10,0
+message db 'SLRboot for SingOS! v0.2.1.0-exp',13,10,0
-;enter_debug_mode db 'Press d to enter bootloader debug mode',13,10,0
+enter_debug_mode db 'Press d to enter bootloader debug mode',13,10,0
-;enter_system_check db 'Performing system check:',13,10,0
+welcome_debug db 'Debug mode v.0.0.1:',13,10,0
-;sys_check_ok db 'System check ok', 13, 10, 0
+error_str db 'Error', 0
-;boot_system db 'Read SingOS from disk', 13, 10, 0
-;error_str db 'Error', 0
-;success_str db 'Success', 0
 boot_this_partition: dw 0
 disk_identifier db 0
 
@@ -283,7 +204,7 @@ partition_1:
 .size db 0x00, 0xC8, 0x03, 0x00  
 
 partition_2:
-.active_partition db 0x80 
+.active_partition db 0x00 
 .start_CHS db 0x8C, 0x3E, 0x0F 
 .disk_type db 0x83 
 .end_CHS db 0xFF, 0xFF, 0xFF 
@@ -311,23 +232,3 @@ dw 0xAA55           ; => 0x55 0xAA (little endian byte order)
 ; bootloder debug_mode goes here
 
 times 8192-($-$$) db 0
-
-
-
-; mov si, 0x7be
-; cmp byte [si], al
-; jne 0x33
-; add si, 0x10
-; cmp si, 0x7fe
-; jne 0x24
-; jmp 0x49
-; mov ah, 2
-; mov al, 1
-; mov bx, 0x7c00
-; mov dl, 0x80
-; mov dh, byte [si + 1]
-; mov cx, word [si + 2]
-; int 0x13
-; jmp long 0:0x7c00
-
-; jmp 0x49