/*
* 该文件实现rs232 串行通信中断处理
*/
/*
* linux/kernel/rs_io.s
*
* (C) 1991 Linus Torvalds
*/
/*
* rs_io.s
*
* This module implements the rs232 io interrupts.
*/
.text
.globl _rs1_interrupt,_rs2_interrupt
/* 读写队列缓冲区的长度 */
size = 1024 /* must be power of two !
and must match the value
in tty_io.c!!! */
/* these are the offsets into the read/write buffer structures */
/* 读写缓冲结构中的偏移量tty_queue */
rs_addr = 0
head = 4
tail = 8
proc_list = 12
buf = 16
/* 当写队列里还剩256 个字符空间(WAKEUP_CHARS)时，我们就可以写 */
startup = 256 /* chars left in write queue when we restart it */
/*
* These are the actual interrupt routines. They look where
* the interrupt is coming from, and take appropriate action.
*/
.align 2
/* 串行端口1 中断处理程序入口点 */
_rs1_interrupt:
// tty 表中对应串口1 的读写缓冲指针的地址入栈
pushl $_table_list+8 // table_list定义在文件tty_io.c文件中
jmp rs_int
/* 串行端口2 中断处理程序入口点 */
.align 2
_rs2_interrupt:
pushl $_table_list+16 // 同上
rs_int:
pushl %edx
pushl %ecx
pushl %ebx
pushl %eax
push %es
push %ds /* as this is an interrupt, we cannot */
/* 让ds、es 指向内核数据段 */
pushl $0x10 /* know that bs is ok. Load it */
pop %ds
pushl $0x10
pop %es
movl 24(%esp),%edx // 将缓冲队列指针地址存入edx 寄存器
movl (%edx),%edx // 取读队列指针(地址)