我的学习之旅(15)tty.c

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模仿linux tty，建立一个console,通过对console的写操作完成字符的显示。

tty.c源代码:

#include <stdarg.h>#include <mem.h>#include <tty.h>#include <console.h>#include <system.h>static  tty_struct_t g_tty_table[MAX_CHANNEL_ID];void tty_init(void){    int i;        for(i=0;i<MAX_CHANNEL_ID;i++) {        memset((unsigned char *)&g_tty_table[i], 0x0, sizeof(tty_struct_t));    }    g_tty_table[CONSOLE_ID].write = console_write;}unsigned char get_char_from_queue(tty_queue_t *q){    unsigned char ch = q->buf[q->tail];    q->tail = ( q->tail + 1 ) & (TTY_BUF_SIZE-1);    return ch;}void put_char_into_queue(tty_queue_t *q, char ch){    q->buf[q->head] = ch;    q->head = ( q->head + 1 )&(TTY_BUF_SIZE - 1);    return;}void tty_write(tty_struct_t *tty, char *buf, unsigned int len){    char *up = buf;    char ch;        if( !tty || !buf  || len == 0 || len > 1024)        return;    if( tty->write == NULL ) {        return;    }        //入write_q队列    while(len > 0 && (((tty->write_q.tail-tty->write_q.head-1)&(TTY_BUF_SIZE-1)))) { //保证队列没满        ch = up[0];        up++;        len--;        tty->write_q.buf[tty->write_q.head] = ch;        tty->write_q.head = (tty->write_q.head+1) & (TTY_BUF_SIZE-1);    }    return tty->write(tty, buf );    }tty_struct_t *get_tty(unsigned int channel_id){    if( channel_id >= MAX_CHANNEL_ID)        return NULL;    return &g_tty_table[channel_id];}

tty.h的源代码：

#ifndef __TTY_H__#define __TTY_H__#define TTY_BUF_SIZE 1024enum {    CONSOLE_ID= 0,    MAX_CHANNEL_ID};typedef struct tty_queue_s {unsigned long data;unsigned long head;unsigned long tail;char buf[TTY_BUF_SIZE];}tty_queue_t;typedef struct tty_struct_s {    tty_queue_t read_q;    tty_queue_t write_q;    void (*write)(void *tty, char *buf);    unsigned int task_id;}tty_struct_t;void tty_init(void);tty_struct_t *get_tty(unsigned int channel_id);unsigned char get_char_from_queue(tty_queue_t *q);#endif

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