titulos

Author: federicogramos

.gdb_history

@@ -1,9 +1,3 @@
-si
-quit
-b *0x7c23
-continue
-b *0x8000
-continue
 continue
 quit
 b *0x8000
@@ -254,3 +248,9 @@ b *0x8000
 continue
 si
 quit
+b *0x8000
+continue
+quit
+b *0x8000
+continue
+quit

asm/bios/mbr.asm

@@ -6,7 +6,8 @@
 ;; os_doc/bios_specs_edd30.pdf
 ;; -- https://github.com/fysnet/FYSOS/blob/master/boot/embr/embr.asm
 ;; http://www.ctyme.com/intr/rb-0708.htm
-;;
+;; -- https://stanislavs.org/helppc/int_10.html
+
 ;; En 16 bits cuando el procesador no es de 16 si no de 32 o 64 pero ejecuta en 
 ;; un modo de 16 bits, prestar atencion a algunas instrucciones: jumps por ejemp
 ;; lo. El mismo opcode lo interpreta en 32 de una manera y en 16 de otra, saltan
@@ -32,30 +33,19 @@ entry:
 	mov [driveNumber], dl	;; Bios passes drive number in dl.
 
 	call pushTest
-
-	mov ah, 0x41			;; Check extensions present.
-	mov bx, 55AAh			;; Required signature.
-	mov dl, [driveNumber]
-	int 0x13
-	jc  notify_ext_not_supported
-	cmp bx, 0xAA55
-	jne notify_ext_not_supported
-
-	mov si, msg_ok
-	call print
+	call extensionTest
 
 	mov si, msg_load
 	call print
 
-	mov ax, 512		;; Load 512 sectors = 262144 bytes = 256 KiB.
+	mov ax, 512		;; Cant sectors. Load 512 = 262144 bytes = 256 KiB.
 	mov bx, 6117	;; Offset = 8192.
 	mov cx, 0x8000	;; Copy here.
 	call diskcpy	;; Copia payload completo.
 
 	mov si, msg_ok
 	call print
 
-
 ;; TO-DO reponer
 	;;mov eax, [0x8000 + 6]
 	;;cmp eax, "BOOT"		; Match against the tsl_start.sys binary
@@ -92,25 +82,21 @@ entry:
 	jmp 0x0000:0x8000
 
 
-
-
-err:
-	mov si, msg_err
-	call print
+;;==============================================================================
+;; errors
+;;==============================================================================
 
 notify_ext_not_supported:
 	mov si, msg_no
 	call print
 
-
-halt:
+.halt:
 	mov si, msg_halt
 	call print
 	hlt
 	jmp $
 
 
-
 ;;==============================================================================
 ;; diskcpy | Copy n sectors from disk.
 ;;==============================================================================
@@ -134,7 +120,7 @@ diskcpy:
 ;; Arguments:
 ;; -- eax: high word of 64 bit sector.
 ;; -- ebx: low word of 64 bit sector.
-;; -- {es:cx}: destination address.
+;; -- {es:cx}: destination address, {seg:offset}
 ;; Returns:
 ;; -- eax: high word of next sector.
 ;; -- ebx: low word of sector.
@@ -143,15 +129,16 @@ diskcpy:
 
 readSec:
 	push eax
-	xor eax, eax	;; We don't need to load from sectors > 32-bit
 	push dx
 	push si
 	push di
 
-read_it:
-	push eax			; Save the sector number
-	push ebx
-	mov di, sp			; remember parameter block end
+	xor eax, eax	;; We don't need to load from sectors > 32-bit
+
+.read:
+	push eax		;; Backup sectorNumber.hi
+	push ebx		;; Backup sectorNumber.lo
+	mov di, sp		;; Base of disk address packet.
 
 	;; Build disk address packet.
 	push eax		;; dap10..15 dap.srcLba.hi
@@ -176,7 +163,7 @@ read_it:
 	xor ah, ah			; else, reset and retry
 	int 0x13
 	pop ax
-	jmp read_it
+	jmp .read
 
 read_ok:
 	add ebx, 1			; increment next sector with carry
@@ -196,67 +183,98 @@ no_incr_es:
 	pop eax
 
 	ret
-;------------------------------------------------------------------------------
 
 
 ;;==============================================================================
-;; pushtest | Verifica compatibilidad de opcode push eax en modo 16 bits
+;; pushTest | Verifica compatibilidad de opcode push eax en modo 16 bits
+;;==============================================================================
+;; Registers CS, DS, ES, SS, BX, CX, DX are preserved unless
+;; explicitly changed
 ;;==============================================================================
 
 pushTest:
 	mov bx, sp
 	push eax
 	sub bx, sp
 	pop eax
-	add [msg_sizeofPush + 32], bl
+	add [msg_sizeofPush + POSITION_COUNT], bl
+
 	mov si, msg_sizeofPush
 	call print
 
+	ret
+
+
+;;==============================================================================
+;; extensionTest | Verifica soporte de extension bios.
+;;==============================================================================
+;; Registers CS, DS, ES, SS, BX, CX, DX are preserved unless
+;; explicitly changed
+;;==============================================================================
+
+extensionTest:
 	mov si, msg_extSupport
 	call print
 
-	ret
+	mov ah, 0x41			;; Check extensions present.
+	mov bx, 55AAh			;; Required signature.
+	mov dl, [driveNumber]
+	int 0x13
+	jc  notify_ext_not_supported
+	cmp bx, 0xAA55
+	jne notify_ext_not_supported
+
+	mov si, msg_ok
+	call print
 
+	ret
 
 
+;;==============================================================================
+;; print | Imprime a pantalla usando bootservice.
+;;==============================================================================
+;; Argumentos:
+;; -- si: string addr 16 bits.
+;;==============================================================================
 
-;------------------------------------------------------------------------------
-; 16-bit function to print a string to the screen
-; IN:	SI - Address of start of string
-print:			; Output string in SI to screen
+print:
 	pusha
-	mov ah, 0x0E			; int 0x10 teletype function
-.repeat:
-	lodsb				; Get char from string
+	mov ah, 0x0e		;; int 0x10: write text in teletype mode.
+
+.next:
+	lodsb
 	cmp al, 0
-	je .done			; If char is zero, end of string
-	int 0x10			; Otherwise, print it
-	jmp short .repeat
-.done:
+	je .fin
+	int 0x10			;; Write boot service.
+	jmp .next
+
+.fin:
 	popa
 	ret
 
 
+;;==============================================================================
+;; section .data
 ;;==============================================================================
 
-
-msg_sizeofPush:	db "16b mode 32b push opcode pushes 0 bytes", 13, 10, 0
+msg_sizeofPush:	db "16b mode 32b push opcode pushes "
+POSITION_COUNT	equ $ - msg_sizeofPush
+				db "0 bytes", 13, 10, 0
 msg_extSupport:	db "Verifying bios ext support..", 0
 msg_no:			db " no", 13, 10, 0
 msg_load:		db "Reading disk..", 0
 msg_ok:			db " ok", 13, 10, 0
-msg_exec:		db "Executing..", 0
-msg_err:		db " error", 0
 msg_halt:		db "Sys halted", 0
 
-driveNumber:		db 0x00
+driveNumber:	db 0x00
 
+;; Zero fill.
 times 446 - $ + $$	db 0
 
-; False partition table entry required by some BIOS vendors.
-db 0x80, 0x00, 0x01, 0x00, 0xEB, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF
+;; False partition table entry required by some BIOS vendors.
+					db 0x80, 0x00, 0x01, 0x00, 0xEB, 0xFF, 0xFF, 0xFF
+					db 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF
 
-;; TO-DO: ld script.
-;;times 510 - $ + $$	db 0
+times 510 - $ + $$	db 0
 
-sign dw 0xAA55
+sign:				dw 0xAA55