说明

该键盘驱动汇编程序主要包括键盘中断处理程序
该程序首先根据键盘特殊键位的状态设置程序后面要用到的状态标志变量mode的值
然后根据引起键盘中断的按键扫描码调用已编排成跳转表的相应扫描码处理子程序，把扫描码对应的字符放入读字符队列中

代码解析

# 引入内核配置头文件，定义键盘语言和硬盘类型
#include <linux/config.h>

.text
# 使得键盘中断外部可调用
.globl keyboard_interrupt

# 键盘缓冲区队列
size	= 1024

# 键盘缓冲队列数据结构tty_queue中的偏移量
head = 4		# 缓冲区头指针字段的偏移量
tail = 8		# 缓冲区尾指针字段的偏移量
proc_list = 12	# 等待该缓冲队列的进程字段的偏移量
buf = 16		# 缓冲区字段的偏移量

# 键盘模式
mode:	.byte 0	# 键盘特殊键位的状态
leds:	.byte 2	# 键盘指示灯的状态标志
e0:	.byte 0		# 收到扫描码0xe0或0xe1时设置的标志

# 键盘中断入口点
keyboard_interrupt:
	# 上下文保存
	pushl %eax
	pushl %ebx
	pushl %ecx
	pushl %edx
	push %ds
	push %es

	# 数据段切换为内核数据段
	movl $0x10,%eax
	mov %ax,%ds
	mov %ax,%es

	# al清零，准备读入字符
	xor %al,%al		/* %eax is scan code */
	# 字符读取
	inb $0x60,%al
	# 判断是否是0xe0或者0xe1
	cmpb $0xe0,%al
	je set_e0
	cmpb $0xe1,%al
	je set_e1

	# 既非0xe0也不是0xe1，则调用key_table中的子程序
	call key_table(,%eax,4)
	# 标识复位
	movb $0,e0

# 对使用8255A的PC标准键盘电路进行硬件复位处理
e0_e1:
	# 从0x61端口读出端口状态并放在al中	
	inb $0x61,%al
	# 1f的意思是向下寻找标号1
	# 此处多余的两次跳转，是为了给读取端口一些时间
	jmp 1f
1:	jmp 1f
	# 将其第7位置1
1:	orb $0x80,%al
	# 下面两次跳转是多余的
	jmp 1f
1:	jmp 1f
	# 将修改后的数值传送回端口，用于禁止键盘工作
	# 并给该操作一些时间
1:	outb %al,$0x61
	jmp 1f
1:	jmp 1f
	# 将其第7位复位(置0)
1:	andb $0x7F,%al
	# 将修改后的数值送回端口，允许键盘工作
	outb %al,$0x61
	# 向8259A中断芯片发送EOI中断结束信号
	movb $0x20,%al
	outb %al,$0x20

	# 传参，调用do_tty_interrupt，保存扫描码对应的数据
	pushl $0
	call do_tty_interrupt
	# 堆栈恢复
	addl $4,%esp

	# 上下文恢复
	pop %es
	pop %ds
	popl %edx
	popl %ecx
	popl %ebx
	popl %eax
	# 中断返回
	iret
	# 收到前导码0xe0时的操作
set_e0:	movb $1,e0
	jmp e0_e1
	# 收到前导码0xe1时的操作
set_e1:	movb $2,e0
	jmp e0_e1

 	# 下面的子程序用于将最多8个字符添加入缓冲队列ebx:eax
put_queue:
	# 上下文保存
	pushl %ecx
	pushl %edx

	# 获取控制台的读缓冲队列
	movl table_list,%edx
	movl head(%edx),%ecx
1:	movb %al,buf(%edx,%ecx)
	incl %ecx
	andl $size-1,%ecx

	# 测试缓冲队列是否已满
	cmpl tail(%edx),%ecx
	# 已满，则直接结束该程序
	je 3f
	# 将ebx中8个bit右移至eax，ebx不变
	shrdl $8,%ebx,%eax
	# 若已完成读取则跳转至2
	je 2f
	# 将ebx高8bit移到低8bit中，然后重复上述操作
	shrl $8,%ebx
	jmp 1b

	# 已完成读取，保存头指针
2:	movl %ecx,head(%edx)
	# 检测是否有等待该队列的进程，如果有就唤醒没有就结束
	movl proc_list(%edx),%ecx
	testl %ecx,%ecx
	je 3f
	movl $0,(%ecx)
	# 上下文恢复
3:	popl %edx
	popl %ecx
	ret

# 下面是key_table中指针对应的各个键位处理子程序
	# 根据ctrl或alt的扫描码设置mode标志
ctrl:	movb $0x04,%al
	jmp 1f
alt:	movb $0x10,%al
1:	cmpb $0,e0
	je 2f
	addb %al,%al
2:	orb %al,mode
	ret

# 处理ctrl或alt松开时的扫描码
unctrl:	movb $0x04,%al
	jmp 1f
unalt:	movb $0x10,%al
1:	cmpb $0,e0
	je 2f
	addb %al,%al
2:	notb %al
	andb %al,mode
	ret

# 处理shift与左右按键按下和松开时的扫描码
lshift:
	orb $0x01,mode
	ret
unlshift:
	andb $0xfe,mode
	ret
rshift:
	orb $0x02,mode
	ret
unrshift:
	andb $0xfd,mode
	ret

# 对caps键扫描码进行处理
caps:	testb $0x80,mode
	jne 1f
	xorb $4,leds
	xorb $0x40,mode
	orb $0x80,mode
set_leds:
	call kb_wait
	movb $0xed,%al		/* set leds command */
	outb %al,$0x60
	call kb_wait
	movb leds,%al
	outb %al,$0x60
	ret
uncaps:	andb $0x7f,mode
	ret
scroll:
	xorb $1,leds
	jmp set_leds
num:	xorb $2,leds
	jmp set_leds

# 对方向键/数字小键盘方向键和数字小键盘进行处理
cursor:
	subb $0x47,%al
	jb 1f
	cmpb $12,%al
	ja 1f
	jne cur2		/* check for ctrl-alt-del */
	testb $0x0c,mode
	je cur2
	testb $0x30,mode
	jne reboot
cur2:	cmpb $0x01,e0		/* e0 forces cursor movement */
	je cur
	testb $0x02,leds	/* not num-lock forces cursor */
	je cur
	testb $0x03,mode	/* shift forces cursor */
	jne cur
	xorl %ebx,%ebx
	movb num_table(%eax),%al
	jmp put_queue
1:	ret
# 处理光标移动或插入删除按键
cur:	movb cur_table(%eax),%al
	cmpb $'9,%al
	ja ok_cur
	movb $'~,%ah
ok_cur:	shll $16,%eax
	movw $0x5b1b,%ax
	xorl %ebx,%ebx
	jmp put_queue

#if defined(KBD_FR)
num_table:
	.ascii "789 456 1230."
#else
num_table:
	.ascii "789 456 1230,"
#endif
cur_table:
	.ascii "HA5 DGC YB623"

# 功能按键处理
func:
	pushl %eax
	pushl %ecx
	pushl %edx
	call show_stat
	popl %edx
	popl %ecx
	popl %eax
	subb $0x3B,%al
	jb end_func
	cmpb $9,%al
	jbe ok_func
	subb $18,%al
	cmpb $10,%al
	jb end_func
	cmpb $11,%al
	ja end_func
ok_func:
	cmpl $4,%ecx		/* check that there is enough room */
	jl end_func
	movl func_table(,%eax,4),%eax
	xorl %ebx,%ebx
	jmp put_queue
end_func:
	ret

/*
 * function keys send F1:'esc [ [ A' F2:'esc [ [ B' etc.
 */
func_table:
	.long 0x415b5b1b,0x425b5b1b,0x435b5b1b,0x445b5b1b
	.long 0x455b5b1b,0x465b5b1b,0x475b5b1b,0x485b5b1b
	.long 0x495b5b1b,0x4a5b5b1b,0x4b5b5b1b,0x4c5b5b1b

# 扫描码与ASCII字符映射表
#if	defined(KBD_FINNISH)
key_map:
	.byte 0,27
	.ascii "1234567890+'"
	.byte 127,9
	.ascii "qwertyuiop}"
	.byte 0,13,0
	.ascii "asdfghjkl|{"
	.byte 0,0
	.ascii "'zxcvbnm,.-"
	.byte 0,'*,0,32		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte '-,0,0,0,'+	/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '<
	.fill 10,1,0

shift_map:
	.byte 0,27
	.ascii "!\"#$%&/()=?`"
	.byte 127,9
	.ascii "QWERTYUIOP]^"
	.byte 13,0
	.ascii "ASDFGHJKL\\["
	.byte 0,0
	.ascii "*ZXCVBNM;:_"
	.byte 0,'*,0,32		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte '-,0,0,0,'+	/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '>
	.fill 10,1,0

alt_map:
	.byte 0,0
	.ascii "\0@\0$\0\0{[]}\\\0"
	.byte 0,0
	.byte 0,0,0,0,0,0,0,0,0,0,0
	.byte '~,13,0
	.byte 0,0,0,0,0,0,0,0,0,0,0
	.byte 0,0
	.byte 0,0,0,0,0,0,0,0,0,0,0
	.byte 0,0,0,0		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte 0,0,0,0,0		/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '|
	.fill 10,1,0

# 美式键盘的扫描码映射表
#elif defined(KBD_US)

key_map:
	.byte 0,27
	.ascii "1234567890-="
	.byte 127,9
	.ascii "qwertyuiop[]"
	.byte 13,0
	.ascii "asdfghjkl;'"
	.byte '`,0
	.ascii "\\zxcvbnm,./"
	.byte 0,'*,0,32		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte '-,0,0,0,'+	/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '<
	.fill 10,1,0


shift_map:
	.byte 0,27
	.ascii "!@#$%^&*()_+"
	.byte 127,9
	.ascii "QWERTYUIOP{}"
	.byte 13,0
	.ascii "ASDFGHJKL:\""
	.byte '~,0
	.ascii "|ZXCVBNM<>?"
	.byte 0,'*,0,32		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte '-,0,0,0,'+	/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '>
	.fill 10,1,0

alt_map:
	.byte 0,0
	.ascii "\0@\0$\0\0{[]}\\\0"
	.byte 0,0
	.byte 0,0,0,0,0,0,0,0,0,0,0
	.byte '~,13,0
	.byte 0,0,0,0,0,0,0,0,0,0,0
	.byte 0,0
	.byte 0,0,0,0,0,0,0,0,0,0,0
	.byte 0,0,0,0		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte 0,0,0,0,0		/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '|
	.fill 10,1,0

#elif defined(KBD_GR)

key_map:
	.byte 0,27
	.ascii "1234567890\\'"
	.byte 127,9
	.ascii "qwertzuiop@+"
	.byte 13,0
	.ascii "asdfghjkl[]^"
	.byte 0,'#
	.ascii "yxcvbnm,.-"
	.byte 0,'*,0,32		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte '-,0,0,0,'+	/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '<
	.fill 10,1,0


shift_map:
	.byte 0,27
	.ascii "!\"#$%&/()=?`"
	.byte 127,9
	.ascii "QWERTZUIOP\\*"
	.byte 13,0
	.ascii "ASDFGHJKL{}~"
	.byte 0,''
	.ascii "YXCVBNM;:_"
	.byte 0,'*,0,32		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte '-,0,0,0,'+	/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '>
	.fill 10,1,0

alt_map:
	.byte 0,0
	.ascii "\0@\0$\0\0{[]}\\\0"
	.byte 0,0
	.byte '@,0,0,0,0,0,0,0,0,0,0
	.byte '~,13,0
	.byte 0,0,0,0,0,0,0,0,0,0,0
	.byte 0,0
	.byte 0,0,0,0,0,0,0,0,0,0,0
	.byte 0,0,0,0		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte 0,0,0,0,0		/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '|
	.fill 10,1,0

# 法语键盘扫描码映射表
#elif defined(KBD_FR)

key_map:
	.byte 0,27
	.ascii "&{\"'(-}_/@)="
	.byte 127,9
	.ascii "azertyuiop^$"
	.byte 13,0
	.ascii "qsdfghjklm|"
	.byte '`,0,42		/* coin sup gauche, don't know, [*|mu] */
	.ascii "wxcvbn,;:!"
	.byte 0,'*,0,32		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte '-,0,0,0,'+	/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '<
	.fill 10,1,0

shift_map:
	.byte 0,27
	.ascii "1234567890]+"
	.byte 127,9
	.ascii "AZERTYUIOP<>"
	.byte 13,0
	.ascii "QSDFGHJKLM%"
	.byte '~,0,'#
	.ascii "WXCVBN?./\\"
	.byte 0,'*,0,32		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte '-,0,0,0,'+	/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '>
	.fill 10,1,0

alt_map:
	.byte 0,0
	.ascii "\0~#{[|`\\^@]}"
	.byte 0,0
	.byte '@,0,0,0,0,0,0,0,0,0,0
	.byte '~,13,0
	.byte 0,0,0,0,0,0,0,0,0,0,0
	.byte 0,0
	.byte 0,0,0,0,0,0,0,0,0,0,0
	.byte 0,0,0,0		/* 36-39 */
	.fill 16,1,0		/* 3A-49 */
	.byte 0,0,0,0,0		/* 4A-4E */
	.byte 0,0,0,0,0,0,0	/* 4F-55 */
	.byte '|
	.fill 10,1,0

#else
#error "KBD-type not defined"
#endif
# 普通按键处理
do_self:
	lea alt_map,%ebx
	testb $0x20,mode		/* alt-gr */
	jne 1f
	lea shift_map,%ebx
	testb $0x03,mode
	jne 1f
	lea key_map,%ebx
1:	movb (%ebx,%eax),%al
	orb %al,%al
	je none
	testb $0x4c,mode		/* ctrl or caps */
	je 2f
	cmpb $'a,%al
	jb 2f
	cmpb $'},%al
	ja 2f
	subb $32,%al
2:	testb $0x0c,mode		/* ctrl */
	je 3f
	cmpb $64,%al
	jb 3f
	cmpb $64+32,%al
	jae 3f
	subb $64,%al
3:	testb $0x10,mode		/* left alt */
	je 4f
	orb $0x80,%al
4:	andl $0xff,%eax
	xorl %ebx,%ebx
	call put_queue
none:	ret

/*
 * minus has a routine of it's own, as a 'E0h' before
 * the scan code for minus means that the numeric keypad
 * slash was pushed.
 */
minus:	cmpb $1,e0
	jne do_self
	movl $'/,%eax
	xorl %ebx,%ebx
	jmp put_queue

/*
 * This table decides which routine to call when a scan-code has been
 * gotten. Most routines just call do_self, or none, depending if
 * they are make or break.
 */

# 下面是键位子程序入口地址表
key_table:
	.long none,do_self,do_self,do_self	/* 00-03 s0 esc 1 2 */
	.long do_self,do_self,do_self,do_self	/* 04-07 3 4 5 6 */
	.long do_self,do_self,do_self,do_self	/* 08-0B 7 8 9 0 */
	.long do_self,do_self,do_self,do_self	/* 0C-0F + ' bs tab */
	.long do_self,do_self,do_self,do_self	/* 10-13 q w e r */
	.long do_self,do_self,do_self,do_self	/* 14-17 t y u i */
	.long do_self,do_self,do_self,do_self	/* 18-1B o p } ^ */
	.long do_self,ctrl,do_self,do_self	/* 1C-1F enter ctrl a s */
	.long do_self,do_self,do_self,do_self	/* 20-23 d f g h */
	.long do_self,do_self,do_self,do_self	/* 24-27 j k l | */
	.long do_self,do_self,lshift,do_self	/* 28-2B { para lshift , */
	.long do_self,do_self,do_self,do_self	/* 2C-2F z x c v */
	.long do_self,do_self,do_self,do_self	/* 30-33 b n m , */
	.long do_self,minus,rshift,do_self	/* 34-37 . - rshift * */
	.long alt,do_self,caps,func		/* 38-3B alt sp caps f1 */
	.long func,func,func,func		/* 3C-3F f2 f3 f4 f5 */
	.long func,func,func,func		/* 40-43 f6 f7 f8 f9 */
	.long func,num,scroll,cursor		/* 44-47 f10 num scr home */
	.long cursor,cursor,do_self,cursor	/* 48-4B up pgup - left */
	.long cursor,cursor,do_self,cursor	/* 4C-4F n5 right + end */
	.long cursor,cursor,cursor,cursor	/* 50-53 dn pgdn ins del */
	.long none,none,do_self,func		/* 54-57 sysreq ? < f11 */
	.long func,none,none,none		/* 58-5B f12 ? ? ? */
	.long none,none,none,none		/* 5C-5F ? ? ? ? */
	.long none,none,none,none		/* 60-63 ? ? ? ? */
	.long none,none,none,none		/* 64-67 ? ? ? ? */
	.long none,none,none,none		/* 68-6B ? ? ? ? */
	.long none,none,none,none		/* 6C-6F ? ? ? ? */
	.long none,none,none,none		/* 70-73 ? ? ? ? */
	.long none,none,none,none		/* 74-77 ? ? ? ? */
	.long none,none,none,none		/* 78-7B ? ? ? ? */
	.long none,none,none,none		/* 7C-7F ? ? ? ? */
	.long none,none,none,none		/* 80-83 ? br br br */
	.long none,none,none,none		/* 84-87 br br br br */
	.long none,none,none,none		/* 88-8B br br br br */
	.long none,none,none,none		/* 8C-8F br br br br */
	.long none,none,none,none		/* 90-93 br br br br */
	.long none,none,none,none		/* 94-97 br br br br */
	.long none,none,none,none		/* 98-9B br br br br */
	.long none,unctrl,none,none		/* 9C-9F br unctrl br br */
	.long none,none,none,none		/* A0-A3 br br br br */
	.long none,none,none,none		/* A4-A7 br br br br */
	.long none,none,unlshift,none		/* A8-AB br br unlshift br */
	.long none,none,none,none		/* AC-AF br br br br */
	.long none,none,none,none		/* B0-B3 br br br br */
	.long none,none,unrshift,none		/* B4-B7 br br unrshift br */
	.long unalt,none,uncaps,none		/* B8-BB unalt br uncaps br */
	.long none,none,none,none		/* BC-BF br br br br */
	.long none,none,none,none		/* C0-C3 br br br br */
	.long none,none,none,none		/* C4-C7 br br br br */
	.long none,none,none,none		/* C8-CB br br br br */
	.long none,none,none,none		/* CC-CF br br br br */
	.long none,none,none,none		/* D0-D3 br br br br */
	.long none,none,none,none		/* D4-D7 br br br br */
	.long none,none,none,none		/* D8-DB br ? ? ? */
	.long none,none,none,none		/* DC-DF ? ? ? ? */
	.long none,none,none,none		/* E0-E3 e0 e1 ? ? */
	.long none,none,none,none		/* E4-E7 ? ? ? ? */
	.long none,none,none,none		/* E8-EB ? ? ? ? */
	.long none,none,none,none		/* EC-EF ? ? ? ? */
	.long none,none,none,none		/* F0-F3 ? ? ? ? */
	.long none,none,none,none		/* F4-F7 ? ? ? ? */
	.long none,none,none,none		/* F8-FB ? ? ? ? */
	.long none,none,none,none		/* FC-FF ? ? ? ? */

# 测试键盘缓冲队列是否为空
kb_wait:
	pushl %eax
1:	inb $0x64,%al
	testb $0x02,%al
	jne 1b
	popl %eax
	ret

# 设置键盘控制器，使系统重启
reboot:
	call kb_wait
	movw $0x1234,0x472	/* don't do memory check */
	movb $0xfc,%al		/* pulse reset and A20 low */
	outb %al,$0x64
die:	jmp die