# along with this program. If not, see <https://www.gnu.org/licenses/>.
.code16
- .section .boot,"a"
+ .section .boot,"ax"
.set stack_top, 0x7be0
.set read_retries, 0x7be8
mov %dl, drive_number
- call setup_serial
-
call get_drive_chs
mov $loading_msg, %si
call read_sectors
jmp boot2_addr
- .set ARG_NSECT, 6
- .set ARG_SIDX, 4
-
loading_msg: .asciz "\nLoad "
driveno_msg: .asciz "Drv:"
+ .global sect_per_track
sect_per_track: .short 18
+ .global num_cylinders
num_cylinders: .short 80
+ .global num_heads
num_heads: .short 2
+ .global heads_mask
heads_mask: .byte 1
get_drive_chs:
mov $8, %ah
int $0x13
- jnc .Lok
+ jnc ok
ret
-.Lok: xor %eax, %eax
+ok: xor %eax, %eax
mov %ch, %al
mov %cl, %ah
rol $2, %ah
call print_num
ret
+
+ .set ARG_NSECT, 6
+ .set ARG_SIDX, 4
+
# read_sectors(first, num)
read_sectors:
push %bp
movw $3, read_retries
-.Lread_try:
+read_try:
# calculate the track (sidx / sectors_per_track)
mov 4(%bp), %ax
mov $0x0201, %ax
movb drive_number, %dl
int $0x13
- jnc .Lread_ok
+ jnc read_ok
# abort after 3 attempts
decw read_retries
- jz .Lread_fail
+ jz read_fail
# error detected, reset controller and retry
xor %ah, %ah
int $0x13
- jmp .Lread_try
+ jmp read_try
-.Lread_fail:
+read_fail:
mov 4(%bp), %ax
jmp abort_read
-.Lread_ok:
+read_ok:
mov $46, %ax
call print_char
0: mov (%si), %al
cmp $0, %al
- jz .Lend
+ jz end
call print_char
inc %si
jmp 0b
-.Lend: popa
+end: popa
ret
# expects character in al
print_char:
push %es
- push %ax
cmp $10, %ax
jnz 0f
mov $32, %ax
movb $7, %es:1(%di)
incw cursor_x
- pop %ax
- call ser_putchar
pop %es
ret
movw $scratchbuf + scratchbuf_size, %si
movb $0, (%si)
mov $10, %ebx
-.Lconvloop:
+convloop:
xor %edx, %edx
div %ebx
add $48, %dl
dec %si
mov %dl, (%si)
cmp $0, %eax
- jnz .Lconvloop
+ jnz convloop
call print_str
popa
ret
- .set UART_DATA, 0x3f8
- .set UART_DIVLO, 0x3f8
- .set UART_DIVHI, 0x3f9
- .set UART_FIFO, 0x3fa
- .set UART_LCTL, 0x3fb
- .set UART_MCTL, 0x3fc
- .set UART_LSTAT, 0x3fd
- .set DIV_9600, 115200 / 9600
- .set LCTL_8N1, 0x03
- .set LCTL_DLAB, 0x80
- .set FIFO_ENABLE_CLEAR, 0x07
- .set MCTL_DTR_RTS_OUT2, 0x0b
- .set LST_TREG_EMPTY, 0x20
-
-setup_serial:
- # set clock divisor
- mov $LCTL_DLAB, %al
- mov $UART_LCTL, %dx
- out %al, %dx
- mov $DIV_9600, %ax
- mov $UART_DIVLO, %dx
- out %al, %dx
- shr $8, %ax
- mov $UART_DIVHI, %dx
- out %al, %dx
- # set format 8n1
- mov $LCTL_8N1, %al
- mov $UART_LCTL, %dx
- out %al, %dx
- # clear and enable fifo
- mov $FIFO_ENABLE_CLEAR, %al
- mov $UART_FIFO, %dx
- out %al, %dx
- # assert RTS and DTR
- mov $MCTL_DTR_RTS_OUT2, %al
- mov $UART_MCTL, %dx
- out %al, %dx
- ret
-
- # expects a character in al
-ser_putchar:
- push %dx
-
- cmp $10, %al
- jnz 0f
- push %ax
- mov $13, %al
- call ser_putchar
- pop %ax
-
-0: mov %al, %ah
- # wait until the transmit register is empty
- mov $UART_LSTAT, %dx
-.Lwait: in %dx, %al
- and $LST_TREG_EMPTY, %al
- jz .Lwait
- mov $UART_DATA, %dx
- mov %ah, %al
- out %al, %dx
-
- pop %dx
- ret
-
.org 510
.byte 0x55
.byte 0xaa