[mirror_edk2.git] / DuetPkg / BootSector / Mbr.S

#------------------------------------------------------------------------------\r
#*\r
#*   Copyright 2006 - 2007, Intel Corporation                                                         \r
#*   All rights reserved. This program and the accompanying materials\r
#*   are licensed and made available under the terms and conditions of the BSD License\r
#*   which accompanies this distribution.  The full text of the license may be found at\r
#*   http://opensource.org/licenses/bsd-license.php\r
#*\r
#*   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
#*   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
#*\r
#*    Mbr.asm\r
#*\r
#*   Abstract:\r
#*\r
#------------------------------------------------------------------------------\r
\r
.equ                      BLOCK_SIZE, 0x0200\r
.equ                      BLOCK_MASK, 0x01ff\r
.equ                      BLOCK_SHIFT, 9\r
\r
# ****************************************************************************\r
# Code loaded by BIOS at 0x0000:0x7C00\r
# ****************************************************************************\r
\r
.org 0x0\r
\r
.global _start\r
_start:\r
\r
# ****************************************************************************\r
# Start Print\r
# ****************************************************************************\r
\r
        movw $0xb800, %ax\r
        movw %ax, %es\r
        movw $0x7c0, %ax\r
        movw %ax, %ds\r
        leaw %cs:StartString, %si\r
        movw $10, %cx\r
        movw $160, %di\r
        rep \r
        movsw\r
\r
# ****************************************************************************\r
# Print over\r
# ****************************************************************************\r
\r
# ****************************************************************************\r
# Initialize segment registers and copy code at 0x0000:0x7c00 to 0x0000:0x0600\r
# ****************************************************************************\r
        xorw  %ax, %ax                            # AX = 0x0000\r
        movw  $0x7c00, %bx                        # BX = 0x7C00\r
        movw  $0x600, %bp                         # BP = 0x0600\r
        movw  RelocatedStart, %si                 # SI = Offset(RelocatedStart)\r
        movw  $0x200, %cx                         # CX = 0x0200\r
        subw  %si, %cx                            # CS = 0x0200 - Offset(RelocatedStart)\r
        leaw  (%bp,%si,), %di                     # DI = 0x0600 + Offset(RelocatedStart)\r
        leaw  (%bx,%si,), %si                     # BX = 0x7C00 + Offset(RelocatedStart)\r
        movw  %ax, %ss                            # SS = 0x0000\r
        movw  %bx, %sp                            # SP = 0x7C00\r
        movw  %ax, %es                            # ES = 0x0000\r
        movw  %ax, %ds                            # DS = 0x0000\r
        pushw %ax                                 # PUSH 0x0000\r
        pushw %di                                 # PUSH 0x0600 + Offset(RelocatedStart)\r
        cld                                       # Clear the direction flag\r
        rep\r
        movsb                                     # Copy 0x0200 bytes from 0x7C00 to 0x0600\r
        retl                                      # JMP 0x0000:0x0600 + Offset(RelocatedStart)\r
\r
# ****************************************************************************\r
# Code relocated to 0x0000:0x0600\r
# ****************************************************************************\r
\r
RelocatedStart: \r
# ****************************************************************************\r
# Get Driver Parameters to 0x0000:0x7BFC\r
# ****************************************************************************\r
\r
        xorw  %ax, %ax                            # AX = 0\r
        movw  %ax, %ss                            # SS = 0\r
        addw  $0x1000, %ax\r
        movw  %ax, %ds\r
\r
        movw  $0x7c00, %sp                        # SP = 0x7c00\r
        movw  %sp, %bp                            # BP = 0x7c00\r
\r
        movb  $8, %ah                             # AH = 8 - Get Drive Parameters Function\r
        movb  %dl, PhysicalDrive(%bp)             # BBS defines that BIOS would pass the booting driver number to the loader through DL\r
        int   $0x13                               # Get Drive Parameters\r
        xorw  %ax, %ax                            # AX = 0\r
        movb  %dh, %al                            # AL = DH\r
        incb  %al                                 # MaxHead = AL + 1\r
        pushw %ax                                 # 0000:7bfe = MaxHead\r
        movb  %cl, %al                            # AL = CL\r
        andb  $0x3f, %al                          # MaxSector = AL & 0x3f\r
        pushw %ax                                 # 0000:7bfc = MaxSector\r
\r
# ****************************************************************************\r
# Read Target DBR from hard disk to 0x0000:0x7C00\r
# ****************************************************************************\r
\r
        xorw  %ax, %ax\r
        movb  MbrPartitionIndicator(%bp), %al          # AX = MbrPartitionIndex\r
        cmpb  $0xff, %al                               # 0xFF means do legacy MBR boot\r
        jnz   EfiDbr\r
LegacyMbr: \r
        movl  $0x0000600, %eax                    # Assume LegacyMBR is backuped in Sector 6\r
        jmp   StartReadTo7C00                     # EAX = Header/Sector/Tracker/Zero\r
\r
EfiDbr: \r
        cmpb  $4, %al                             # MbrPartitionIndex should < 4\r
        jae   BadDbr\r
        shlw  $4, %ax                             # AX  = MBREntrySize * Index\r
        addw  $0x1be, %ax                         # AX  = MBREntryOffset\r
        movw  %ax, %di                            # DI  = MBREntryOffset\r
\r
        # Here we don't use the C/H/S information provided by Partition table\r
        #  but calculate C/H/S from LBA ourselves\r
        #       Ci: Cylinder number\r
        #       Hi: Header number\r
        #       Si: Sector number\r
        movl  %es:8(%bp,%di,), %eax               # Start LBA\r
        movl  %eax, %edx\r
        shrl  $16, %edx                           # DX:AX = Start LBA\r
                                                  #       = Ci * (H * S) + Hi * S + (Si - 1)\r
\r
        # Calculate C/H/S according to LBA\r
        movw  $0x7bfa, %bp\r
        divw  2(%bp)                              # AX = Hi + H*Ci\r
                                                  # DX = Si - 1\r
        incw  %dx                                 # DX = Si\r
        pushw %dx                                 # 0000:7bfa = Si  <----\r
        xorw  %dx, %dx                            # DX:AX = Hi + H*Ci\r
        divw  4(%bp)                              # AX = Ci         <----\r
                                                  # DX = Hi         <----\r
\r
StartReadTo7C00: \r
\r
        movb  (%bp), %cl                          # Si\r
        movb  %al, %ch                            # Ci[0-7]\r
        orb   %ah, %cl                            # Ci[8,9]\r
        movw  $0x7c00, %bx                        # ES:BX = 0000:7C00h\r
        movb  $0x2, %ah                           # Function 02h\r
        movb  $1, %al                             # 1 Sector\r
        movb  %dl, %dh                            # Hi\r
        movw  $0x600, %bp\r
        movb  PhysicalDrive(%bp), %dl             # Drive number\r
        int   $0x13\r
        jc    BadDbr\r
\r
\r
\r
# ****************************************************************************\r
# Transfer control to BootSector - Jump to 0x0000:0x7C00\r
# ****************************************************************************\r
        xorw  %ax, %ax\r
        pushw %ax                                 # PUSH 0x0000 - Segment\r
        movw  $0x7c00, %di\r
        pushw %di                                 # PUSH 0x7C00 - Offset\r
        retl                                      # JMP 0x0000:0x7C00\r
\r
# ****************************************************************************\r
# ERROR Condition:\r
# ****************************************************************************\r
\r
BadDbr: \r
    pushw %ax\r
    movw $0xb800, %ax\r
    movw %ax, %es\r
    movw $0x60, %ax\r
    movw %ax, %ds\r
    leaw %cs:ErrorString, %si\r
    movw $320, %di\r
    popw %ax\r
    call A2C\r
    movb %ah, 16(%si)\r
    movb %al, 18(%si)\r
    movw $10, %cx\r
    rep\r
    movsw\r
Halt: \r
    jmp   Halt\r
\r
StartString: \r
.byte 'M', 0x0c, 'B', 0x0c, 'R', 0x0c, ' ', 0x0c, 'S', 0x0c, 't', 0x0c, 'a', 0x0c, 'r', 0x0c, 't', 0x0c, '!', 0x0c\r
ErrorString: \r
.byte 'M', 0x0c, 'B', 0x0c, 'R', 0x0c, ' ', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, ':', 0x0c, '?', 0x0c, '?', 0x0c\r
\r
# ****************************************************************************\r
# A2C - convert Ascii code stored in AH to character stored in AX\r
# ****************************************************************************\r
A2C: \r
    movb %ah, %al\r
    shrb $4, %ah\r
    andb $0xF, %al\r
    addb '0', %ah\r
    addb '0', %al\r
\r
    cmpb '9', %ah\r
    jle  A2C_L1\r
    addb $7, %ah\r
A2C_L1: \r
\r
    cmpb '9', %al\r
    jle A2C_L2\r
    addb $7, %al\r
A2C_L2: \r
    ret\r
\r
\r
# ****************************************************************************\r
# PhysicalDrive - Used to indicate which disk to be boot\r
#                 Can be patched by tool\r
# ****************************************************************************\r
.org   0x01B6\r
PhysicalDrive:        .byte 0x80\r
\r
# ****************************************************************************\r
# MbrPartitionIndicator - Used to indicate which MBR partition to be boot\r
#                         Can be patched by tool\r
#                         OxFF means boot to legacy MBR. (LBA OFFSET 6)\r
# ****************************************************************************\r
.org   0x01B7\r
MbrPartitionIndicator: .byte 0\r
\r
# ****************************************************************************\r
# Unique MBR signature\r
# ****************************************************************************\r
.org   0x01B8\r
    .ascii "DUET"\r
\r
# ****************************************************************************\r
# Unknown\r
# ****************************************************************************\r
.org   0x01BC\r
    .word 0\r
\r
# ****************************************************************************\r
# MBR Entry - To be patched\r
# ****************************************************************************\r
.org   0x01BE\r
    .long 0,0,0,0\r
.org   0x01CE\r
    .long 0,0,0,0\r
.org   0x01DE\r
    .long 0,0,0,0\r
.org   0x01EE\r
    .long 0,0,0,0\r
\r
# ****************************************************************************\r
# Sector Signature\r
# ****************************************************************************\r
\r
.org 0x01FE\r
SectorSignature: \r
  .word     0xaa55      # Boot Sector Signature\r
\r
\r
\r
Commit	Line	Data
f3eb2131	1	#------------------------------------------------------------------------------\r
	2	#*\r
	3	#* Copyright 2006 - 2007, Intel Corporation \r
	4	#* All rights reserved. This program and the accompanying materials\r
	5	#* are licensed and made available under the terms and conditions of the BSD License\r
	6	#* which accompanies this distribution. The full text of the license may be found at\r
	7	#* http://opensource.org/licenses/bsd-license.php\r
	8	#*\r
	9	#* THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
	10	#* WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
	11	#*\r
	12	#* Mbr.asm\r
	13	#*\r
	14	#* Abstract:\r
	15	#*\r
	16	#------------------------------------------------------------------------------\r
	17	\r
	18	.equ BLOCK_SIZE, 0x0200\r
	19	.equ BLOCK_MASK, 0x01ff\r
	20	.equ BLOCK_SHIFT, 9\r
	21	\r
	22	# ****************************************************************************\r
	23	# Code loaded by BIOS at 0x0000:0x7C00\r
	24	# ****************************************************************************\r
	25	\r
	26	.org 0x0\r
	27	\r
ae3d1e91	28	.global _start\r
f3eb2131	29	_start:\r
	30	\r
	31	# ****************************************************************************\r
	32	# Start Print\r
	33	# ****************************************************************************\r
	34	\r
	35	movw $0xb800, %ax\r
	36	movw %ax, %es\r
	37	movw $0x7c0, %ax\r
	38	movw %ax, %ds\r
	39	leaw %cs:StartString, %si\r
	40	movw $10, %cx\r
	41	movw $160, %di\r
	42	rep \r
	43	movsw\r
	44	\r
	45	# ****************************************************************************\r
	46	# Print over\r
	47	# ****************************************************************************\r
	48	\r
	49	# ****************************************************************************\r
	50	# Initialize segment registers and copy code at 0x0000:0x7c00 to 0x0000:0x0600\r
	51	# ****************************************************************************\r
	52	xorw %ax, %ax # AX = 0x0000\r
	53	movw $0x7c00, %bx # BX = 0x7C00\r
	54	movw $0x600, %bp # BP = 0x0600\r
	55	movw RelocatedStart, %si # SI = Offset(RelocatedStart)\r
	56	movw $0x200, %cx # CX = 0x0200\r
	57	subw %si, %cx # CS = 0x0200 - Offset(RelocatedStart)\r
	58	leaw (%bp,%si,), %di # DI = 0x0600 + Offset(RelocatedStart)\r
	59	leaw (%bx,%si,), %si # BX = 0x7C00 + Offset(RelocatedStart)\r
	60	movw %ax, %ss # SS = 0x0000\r
	61	movw %bx, %sp # SP = 0x7C00\r
	62	movw %ax, %es # ES = 0x0000\r
	63	movw %ax, %ds # DS = 0x0000\r
	64	pushw %ax # PUSH 0x0000\r
	65	pushw %di # PUSH 0x0600 + Offset(RelocatedStart)\r
	66	cld # Clear the direction flag\r
	67	rep\r
	68	movsb # Copy 0x0200 bytes from 0x7C00 to 0x0600\r
	69	retl # JMP 0x0000:0x0600 + Offset(RelocatedStart)\r
	70	\r
	71	# ****************************************************************************\r
	72	# Code relocated to 0x0000:0x0600\r
	73	# ****************************************************************************\r
	74	\r
	75	RelocatedStart: \r
	76	# ****************************************************************************\r
	77	# Get Driver Parameters to 0x0000:0x7BFC\r
	78	# ****************************************************************************\r
	79	\r
	80	xorw %ax, %ax # AX = 0\r
	81	movw %ax, %ss # SS = 0\r
	82	addw $0x1000, %ax\r
	83	movw %ax, %ds\r
	84	\r
	85	movw $0x7c00, %sp # SP = 0x7c00\r
	86	movw %sp, %bp # BP = 0x7c00\r
	87	\r
	88	movb $8, %ah # AH = 8 - Get Drive Parameters Function\r
	89	movb %dl, PhysicalDrive(%bp) # BBS defines that BIOS would pass the booting driver number to the loader through DL\r
	90	int $0x13 # Get Drive Parameters\r
	91	xorw %ax, %ax # AX = 0\r
	92	movb %dh, %al # AL = DH\r
93	incb %al # MaxHead = AL + 1\r
94	pushw %ax # 0000:7bfe = MaxHead\r
95	movb %cl, %al # AL = CL\r
96	andb $0x3f, %al # MaxSector = AL & 0x3f\r
97	pushw %ax # 0000:7bfc = MaxSector\r
98	\r
99	# ****************************************************************************\r
100	# Read Target DBR from hard disk to 0x0000:0x7C00\r
101	# ****************************************************************************\r
102	\r
103	xorw %ax, %ax\r
104	movb MbrPartitionIndicator(%bp), %al # AX = MbrPartitionIndex\r
105	cmpb $0xff, %al # 0xFF means do legacy MBR boot\r
106	jnz EfiDbr\r
107	LegacyMbr: \r
108	movl $0x0000600, %eax # Assume LegacyMBR is backuped in Sector 6\r
109	jmp StartReadTo7C00 # EAX = Header/Sector/Tracker/Zero\r
110	\r
111	EfiDbr: \r
112	cmpb $4, %al # MbrPartitionIndex should < 4\r
113	jae BadDbr\r
114	shlw $4, %ax # AX = MBREntrySize * Index\r
115	addw $0x1be, %ax # AX = MBREntryOffset\r
116	movw %ax, %di # DI = MBREntryOffset\r
117	\r
118	# Here we don't use the C/H/S information provided by Partition table\r
119	# but calculate C/H/S from LBA ourselves\r
120	# Ci: Cylinder number\r
121	# Hi: Header number\r
122	# Si: Sector number\r
123	movl %es:8(%bp,%di,), %eax # Start LBA\r
124	movl %eax, %edx\r
125	shrl $16, %edx # DX:AX = Start LBA\r
126	# = Ci * (H * S) + Hi * S + (Si - 1)\r
127	\r
128	# Calculate C/H/S according to LBA\r
129	movw $0x7bfa, %bp\r
130	divw 2(%bp) # AX = Hi + H*Ci\r
131	# DX = Si - 1\r
132	incw %dx # DX = Si\r
133	pushw %dx # 0000:7bfa = Si <----\r
134	xorw %dx, %dx # DX:AX = Hi + H*Ci\r
135	divw 4(%bp) # AX = Ci <----\r
136	# DX = Hi <----\r
137	\r
138	StartReadTo7C00: \r
139	\r
140	movb (%bp), %cl # Si\r
141	movb %al, %ch # Ci[0-7]\r
142	orb %ah, %cl # Ci[8,9]\r
143	movw $0x7c00, %bx # ES:BX = 0000:7C00h\r
144	movb $0x2, %ah # Function 02h\r
145	movb $1, %al # 1 Sector\r
146	movb %dl, %dh # Hi\r
147	movw $0x600, %bp\r
148	movb PhysicalDrive(%bp), %dl # Drive number\r
149	int $0x13\r
150	jc BadDbr\r
151	\r
152	\r
153	\r
154	# ****************************************************************************\r
155	# Transfer control to BootSector - Jump to 0x0000:0x7C00\r
156	# ****************************************************************************\r
157	xorw %ax, %ax\r
158	pushw %ax # PUSH 0x0000 - Segment\r
159	movw $0x7c00, %di\r
160	pushw %di # PUSH 0x7C00 - Offset\r
161	retl # JMP 0x0000:0x7C00\r
162	\r
163	# ****************************************************************************\r
164	# ERROR Condition:\r
165	# ****************************************************************************\r
166	\r
167	BadDbr: \r
168	pushw %ax\r
169	movw $0xb800, %ax\r
170	movw %ax, %es\r
171	movw $0x60, %ax\r
172	movw %ax, %ds\r
173	leaw %cs:ErrorString, %si\r
174	movw $320, %di\r
175	popw %ax\r
176	call A2C\r
177	movb %ah, 16(%si)\r
178	movb %al, 18(%si)\r
179	movw $10, %cx\r
180	rep\r
181	movsw\r
182	Halt: \r
183	jmp Halt\r
184	\r
185	StartString: \r
186	.byte 'M', 0x0c, 'B', 0x0c, 'R', 0x0c, ' ', 0x0c, 'S', 0x0c, 't', 0x0c, 'a', 0x0c, 'r', 0x0c, 't', 0x0c, '!', 0x0c\r
187	ErrorString: \r
188	.byte 'M', 0x0c, 'B', 0x0c, 'R', 0x0c, ' ', 0x0c, 'E', 0x0c, 'r', 0x0c, 'r', 0x0c, ':', 0x0c, '?', 0x0c, '?', 0x0c\r
189	\r
190	# ****************************************************************************\r
191	# A2C - convert Ascii code stored in AH to character stored in AX\r
192	# ****************************************************************************\r
193	A2C: \r
194	movb %ah, %al\r
195	shrb $4, %ah\r
196	andb $0xF, %al\r
197	addb '0', %ah\r
198	addb '0', %al\r
199	\r
200	cmpb '9', %ah\r
201	jle A2C_L1\r
202	addb $7, %ah\r
203	A2C_L1: \r
204	\r
205	cmpb '9', %al\r
206	jle A2C_L2\r
207	addb $7, %al\r
208	A2C_L2: \r
209	ret\r
210	\r
211	\r
212	# ****************************************************************************\r
213	# PhysicalDrive - Used to indicate which disk to be boot\r
214	# Can be patched by tool\r
215	# ****************************************************************************\r
216	.org 0x01B6\r
217	PhysicalDrive: .byte 0x80\r
218	\r
219	# ****************************************************************************\r
220	# MbrPartitionIndicator - Used to indicate which MBR partition to be boot\r
221	# Can be patched by tool\r
222	# OxFF means boot to legacy MBR. (LBA OFFSET 6)\r
223	# ****************************************************************************\r
224	.org 0x01B7\r
225	MbrPartitionIndicator: .byte 0\r
226	\r
227	# ****************************************************************************\r
228	# Unique MBR signature\r
229	# ****************************************************************************\r
230	.org 0x01B8\r
231	.ascii "DUET"\r
232	\r
233	# ****************************************************************************\r
234	# Unknown\r
235	# ****************************************************************************\r
236	.org 0x01BC\r
237	.word 0\r
238	\r
239	# ****************************************************************************\r
240	# MBR Entry - To be patched\r
241	# ****************************************************************************\r
242	.org 0x01BE\r
243	.long 0,0,0,0\r
244	.org 0x01CE\r
245	.long 0,0,0,0\r
246	.org 0x01DE\r
247	.long 0,0,0,0\r
248	.org 0x01EE\r
249	.long 0,0,0,0\r
250	\r
251	# ****************************************************************************\r
252	# Sector Signature\r
253	# ****************************************************************************\r
254	\r
255	.org 0x01FE\r
256	SectorSignature: \r
257	.word 0xaa55 # Boot Sector Signature\r
258	\r
259	\r
260	\r