程序集:用于自定义操作系统键盘支持的引导加载程序 [英] Assembly: boot loader for custom OS keyboard support
问题描述
我有一个简单的自定义操作系统(目前没有做太多事情:D).现在我正在使用不支持键盘的程序集文件 (boot.s).
I have a working simple custom OS (doesn't do much for now :D). Right now i'm using an assembly file (boot.s) that has no keyboard support.
汇编文件(boot.s):
The assembly file (boot.s):
# set magic number to 0x1BADB002 to identified by bootloader
.set MAGIC, 0x1BADB002
# set flags to 0
.set FLAGS, 0
# set the checksum
.set CHECKSUM, -(MAGIC + FLAGS)
# set multiboot enabled
.section .multiboot
# define type to long for each data defined as above
.long MAGIC
.long FLAGS
.long CHECKSUM
# set the stack bottom
stackBottom:
# define the maximum size of stack to 512 bytes
.skip 512
# set the stack top which grows from higher to lower
stackTop:
.section .text
.global _start
.type _start, @function
_start:
# assign current stack pointer location to stackTop
mov $stackTop, %esp
# call the kernel main source
call KERNEL_MAIN
cli
# put system in infinite loop
hltLoop:
hlt
jmp hltLoop
.size _start, . - _start
我认为这是缺失的部分,但它是 intel 语法,我无法使用它.
I think this is the missing part but it is in intel syntax and i cannot use it.
load_idt:
mov edx, [esp + 4]
lidt [edx]
sti
ret
read_port:
mov edx, [esp + 4]
in al, dx
ret
write_port:
mov edx, [esp + 4]
mov al, [esp + 4 + 4]
out dx, al
ret
keyboard_handler:
call keyboard_handler
iretd
我正在使用以下命令编译 boot.s:
I'm compiling the boot.s with the following command:
as --32 boot.s -o boot.o
谁能帮我将键盘部分(英特尔语法)翻译成 AT&T?:)
Can anyone help me translating the keyboard part (Intel syntax) to AT&T? :)
推荐答案
有关如何将 NASM Intel 语法转换为 GAS 的 AT&T 语法的信息可以在此 Stackoverflow 答案,此IBM 文章.您的代码将如下所示:
Information on how you can go about translating NASM Intel syntax to GAS's AT&T syntax can be found in this Stackoverflow Answer, and a lot of useful information is provided in this IBM article. Your code in particular would look like:
load_idt:
mov 4(%esp), %edx
lidt (%edx)
sti
ret
read_port:
mov 4(%esp), %edx
in %dx, %al
ret
write_port:
mov 4(%esp), %edx
mov 8(%esp), %al
out %al, %dx
ret
keyboard_handler:
call keyboard_handler
iret
总的来说,最大的区别是:
In general the biggest differences are:
- 对于 AT&T 语法,源在左侧,目的地在右侧,而英特尔则相反.
- 使用 AT&T 语法的寄存器名称前面带有
%
- 在 AT&T 语法中,立即数前面带有
$
- 内存操作数可能是最大的区别.NASM 使用 [segment:disp+base+index*scale] 而不是 GAS 的 segment:disp(base, index, scale) 语法.
- With AT&T syntax the source is on the left and destination is on the right and Intel is the reverse.
- With AT&T syntax register names are prepended with a
%
- With AT&T syntax immediate values are prepended with a
$
- Memory operands are probably the biggest difference. NASM uses [segment:disp+base+index*scale] instead of GAS's syntax of segment:disp(base, index, scale).
我建议将堆栈从多重引导部分移到 .bss
部分.BSS 部分通常不会占用输出可执行文件中的空间(假设使用的是正常或默认的链接器脚本).可以在 .text
部分之后以这种方式定义堆栈:
I recommend moving the stack out of the multiboot section into the .bss
section. The BSS section doesn't generally take up space in the output executable (assuming one is using a sane or default linker script). The stack could be defined this way after the .text
section:
.section .bss
.lcomm stackBottom 512
stackTop:
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