404 lines
5.8 KiB
ArmAsm
404 lines
5.8 KiB
ArmAsm
.include "common.S"
|
|
|
|
.set SCREEN_WIDTH, 80
|
|
.set SCREEN_HEIGHT, 25
|
|
|
|
.code16
|
|
|
|
.section .stage1
|
|
|
|
# prints character to screen
|
|
# al: ascii character to print
|
|
.global putc
|
|
putc:
|
|
pushw %ax
|
|
pushw %bx
|
|
movb $0x0E, %ah
|
|
xorb %bh, %bh
|
|
int $0x10
|
|
popw %bx
|
|
popw %ax
|
|
ret
|
|
|
|
# prints null terminated string to screen
|
|
# ds:si: string address
|
|
.global puts
|
|
puts:
|
|
pushw %si
|
|
pushw %bx
|
|
pushw %ax
|
|
|
|
movb $0x0E, %ah
|
|
xorb %bh, %bh
|
|
|
|
.puts_loop:
|
|
lodsb
|
|
|
|
test %al, %al
|
|
jz .puts_done
|
|
|
|
int $0x10
|
|
jmp .puts_loop
|
|
|
|
.puts_done:
|
|
popw %ax
|
|
popw %bx
|
|
popw %si
|
|
ret
|
|
|
|
# compares memory between addresses
|
|
# si: ptr1
|
|
# di: ptr2
|
|
# cx: bytes count
|
|
# return:
|
|
# al: 1 if equal, 0 otherwise
|
|
.global memcmp
|
|
memcmp:
|
|
# NOTE: using pusha + popa to save space
|
|
pusha
|
|
cld
|
|
repe cmpsb
|
|
popa
|
|
setzb %al
|
|
ret
|
|
|
|
|
|
.section .stage2
|
|
|
|
# read a character from keyboard
|
|
# return:
|
|
# al: ascii
|
|
# ah: bios scan code
|
|
.global getc
|
|
getc:
|
|
movb $0x00, %ah
|
|
int $0x16
|
|
ret
|
|
|
|
# prints newline to screen
|
|
.global print_newline
|
|
print_newline:
|
|
pushw %ax
|
|
movb $'\r', %al
|
|
call putc
|
|
movb $'\n', %al
|
|
call putc
|
|
pop %ax
|
|
ret
|
|
|
|
# prints backspace to screen, can go back a line
|
|
.global print_backspace
|
|
print_backspace:
|
|
pushw %ax
|
|
pushw %bx
|
|
pushw %cx
|
|
pushw %dx
|
|
|
|
# get cursor position
|
|
movb $0x03, %ah
|
|
movb $0x00, %bh
|
|
int $0x10
|
|
|
|
# don't do anyting if on first row
|
|
testb %dh, %dh
|
|
jz .print_backspace_done
|
|
|
|
# go one line up if on first column
|
|
test %dl, %dl
|
|
jz .print_backspace_go_line_up
|
|
|
|
# otherwise decrease column
|
|
decb %dl
|
|
jmp .print_backspace_do_print
|
|
|
|
.print_backspace_go_line_up:
|
|
# decrease row and set column to the last one
|
|
decb %dh
|
|
movb $(SCREEN_WIDTH - 1), %dl
|
|
|
|
.print_backspace_do_print:
|
|
# set cursor position
|
|
movb $0x02, %ah
|
|
int $0x10
|
|
|
|
# print 'empty' character (space)
|
|
mov $' ', %al
|
|
call putc
|
|
|
|
# set cursor position
|
|
movb $0x02, %ah
|
|
int $0x10
|
|
|
|
.print_backspace_done:
|
|
popw %dx
|
|
popw %cx
|
|
popw %bx
|
|
popw %ax
|
|
ret
|
|
|
|
# print number to screen
|
|
# ax: number to print
|
|
# bx: number base
|
|
# cx: min width (zero pads if shorter)
|
|
.global print_number
|
|
print_number:
|
|
pusha
|
|
pushl %ebp
|
|
movl %esp, %ebp
|
|
|
|
# save min width
|
|
subl $4, %esp
|
|
movw %cx, (%esp)
|
|
|
|
movw $print_number_buffer, %si
|
|
xorw %cx, %cx
|
|
|
|
.print_number_fill_loop:
|
|
# fill buffer with all remainders ax % bx
|
|
xorw %dx, %dx
|
|
divw %bx
|
|
movb %dl, (%si)
|
|
incw %si
|
|
incw %cx
|
|
testw %ax, %ax
|
|
jnz .print_number_fill_loop
|
|
|
|
# check if zero pad is required
|
|
cmpw (%esp), %cx
|
|
jae .print_number_print_loop
|
|
|
|
# dx: saved number count
|
|
# cx: zero pad count
|
|
movw %cx, %dx
|
|
movw (%esp), %cx
|
|
subw %dx, %cx
|
|
movb $'0', %al
|
|
|
|
.print_number_pad_zeroes:
|
|
call putc
|
|
loop .print_number_pad_zeroes
|
|
|
|
# restore number count
|
|
movw %dx, %cx
|
|
|
|
.print_number_print_loop:
|
|
decw %si
|
|
movb (%si), %al
|
|
cmpb $10, %al
|
|
jae .print_number_hex
|
|
addb $'0', %al
|
|
jmp .print_number_do_print
|
|
.print_number_hex:
|
|
addb $('a' - 10), %al
|
|
.print_number_do_print:
|
|
call putc
|
|
loop .print_number_print_loop
|
|
|
|
leavel
|
|
popa
|
|
ret
|
|
|
|
# prints 8 bit hexadecimal number to screen
|
|
# al: number to print
|
|
.global print_hex8
|
|
print_hex8:
|
|
pushw %ax
|
|
pushw %bx
|
|
pushw %cx
|
|
|
|
movw $16, %bx
|
|
movw $2, %cx
|
|
andw $0xFF, %ax
|
|
call print_number
|
|
|
|
popw %cx
|
|
popw %bx
|
|
popw %ax
|
|
ret
|
|
|
|
# prints 16 bit hexadecimal number to screen
|
|
# ax: number to print
|
|
.global print_hex16
|
|
print_hex16:
|
|
pushw %bx
|
|
pushw %cx
|
|
|
|
movw $16, %bx
|
|
movw $4, %cx
|
|
call print_number
|
|
|
|
popw %cx
|
|
popw %bx
|
|
ret
|
|
|
|
# prints 32 bit hexadecimal number to screen
|
|
# eax: number to print
|
|
.global print_hex32
|
|
print_hex32:
|
|
pushl %eax
|
|
pushw %dx
|
|
|
|
movw %ax, %dx
|
|
|
|
shrl $16, %eax;
|
|
call print_hex16
|
|
|
|
movw %dx, %ax
|
|
call print_hex16
|
|
|
|
popw %dx
|
|
popl %eax
|
|
ret
|
|
|
|
# prints 64 bit hexadecimal number to screen
|
|
# edx:eax: number to print
|
|
.global print_hex64
|
|
print_hex64:
|
|
xchgl %eax, %edx
|
|
call print_hex32
|
|
xchgl %eax, %edx
|
|
call print_hex32
|
|
ret
|
|
|
|
# test if character is printable ascii
|
|
# al: character to test
|
|
# return:
|
|
# al: 1 if is printable, 0 otherwise
|
|
.global isprint
|
|
isprint:
|
|
subb $0x20, %al
|
|
cmpb $(0x7E - 0x20), %al
|
|
ja .isprint_not_printable
|
|
movb $1, %al
|
|
ret
|
|
.isprint_not_printable:
|
|
movb $0, %al
|
|
ret
|
|
|
|
|
|
# memset with 32 bit registers
|
|
# edi: destination address
|
|
# ecx: bytes count
|
|
# al: value to set
|
|
# return:
|
|
# edi: destination address + bytes count
|
|
# ecx: 0
|
|
# other: preserved
|
|
.global memset32
|
|
memset32:
|
|
testl %ecx, %ecx
|
|
jz .memset32_done
|
|
|
|
pushf; cli
|
|
pushw %es
|
|
pushl %eax
|
|
pushl %ebx
|
|
pushl %edx
|
|
|
|
movl %cr0, %ebx
|
|
orb $1, %bl
|
|
movl %ebx, %cr0
|
|
|
|
ljmpl $GDT_CODE32, $.memset32_pmode32
|
|
|
|
.code32
|
|
.memset32_pmode32:
|
|
movw $GDT_DATA32, %dx
|
|
movw %dx, %es
|
|
|
|
movl %ecx, %edx
|
|
|
|
andl $3, %ecx
|
|
rep stosb %es:(%edi)
|
|
|
|
movl %edx, %ecx
|
|
shrl $2, %ecx
|
|
|
|
movb %al, %ah
|
|
movw %ax, %dx
|
|
shll $16, %eax
|
|
movw %dx, %ax
|
|
rep stosl %es:(%edi)
|
|
|
|
ljmpl $GDT_CODE16, $.memset32_pmode16
|
|
|
|
.code16
|
|
.memset32_pmode16:
|
|
andb $0xFE, %bl
|
|
movl %ebx, %cr0
|
|
ljmpl $0x00, $.memset32_rmode16
|
|
|
|
.memset32_rmode16:
|
|
popl %edx
|
|
popl %ebx
|
|
popl %eax
|
|
popw %es
|
|
popf
|
|
|
|
.memset32_done:
|
|
ret
|
|
|
|
# memcpy with 32 bit registers
|
|
# esi: source address
|
|
# edi: destination address
|
|
# ecx: bytes count
|
|
# return:
|
|
# esi: source address + bytes count
|
|
# edi: destination address + bytes count
|
|
# ecx: 0
|
|
# other: preserved
|
|
.global memcpy32
|
|
memcpy32:
|
|
testl %ecx, %ecx
|
|
jz .memcpy32_done
|
|
|
|
pushf; cli
|
|
pushw %ds
|
|
pushw %es
|
|
pushl %ebx
|
|
pushl %edx
|
|
|
|
movl %cr0, %ebx
|
|
orb $1, %bl
|
|
movl %ebx, %cr0
|
|
|
|
ljmpl $GDT_CODE32, $.memcpy32_pmode32
|
|
|
|
.code32
|
|
.memcpy32_pmode32:
|
|
movw $GDT_DATA32, %dx
|
|
movw %dx, %ds
|
|
movw %dx, %es
|
|
|
|
movl %ecx, %edx
|
|
andl $3, %ecx
|
|
rep movsb %ds:(%esi), %es:(%edi)
|
|
|
|
movl %edx, %ecx
|
|
shrl $2, %ecx
|
|
rep movsl %ds:(%esi), %es:(%edi)
|
|
|
|
ljmpl $GDT_CODE16, $.memcpy32_pmode16
|
|
|
|
.code16
|
|
.memcpy32_pmode16:
|
|
andb $0xFE, %bl
|
|
movl %ebx, %cr0
|
|
ljmpl $0x00, $.memcpy32_rmode16
|
|
|
|
.memcpy32_rmode16:
|
|
popl %edx
|
|
popl %ebx
|
|
popw %es
|
|
popw %ds
|
|
popf
|
|
|
|
.memcpy32_done:
|
|
ret
|
|
|
|
.section .bss
|
|
|
|
# enough for base 2 printing
|
|
print_number_buffer:
|
|
.skip 16
|