68 lines
1.3 KiB
C
68 lines
1.3 KiB
C
#include <type.h>
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#include <x86.h>
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#include <kern/keymap.h>
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#include <kern/trap.h>
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#define KB_INBUF_SIZE 1024
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typedef struct kb_inbuf {
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u32 lock;
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u8* p_head;
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u8* p_tail;
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int count;
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u8 buf[KB_INBUF_SIZE];
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} KB_INPUT;
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static KB_INPUT kb_input = {
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.p_head = kb_input.buf,
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.p_tail = kb_input.buf,
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};
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/*
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* 将ch这个字符放进内核的字符缓冲区
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*/
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void
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add_keyboard_buf(u8 ch)
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{
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// 上个自旋锁，保证线程安全（不建议用中断）计组课上讲过，相信大家的记忆力
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while (xchg(&kb_input.lock, 1) == 1);
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if (kb_input.count == KB_INBUF_SIZE)
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goto free;
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*kb_input.p_tail++ = ch;
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if (kb_input.p_tail == kb_input.buf + KB_INBUF_SIZE)
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kb_input.p_tail = kb_input.buf;
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kb_input.count++;
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free:
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xchg(&kb_input.lock, 0);
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}
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/*
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* 如果内核的字符缓冲区为空，则返回-1
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* 否则返回缓冲区队头的字符并弹出队头
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*/
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u8
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read_keyboard_buf(void)
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{
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u8 res;
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// 上个自旋锁，保证线程安全（不建议用中断）计组课上讲过，相信大家的记忆力
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while (xchg(&kb_input.lock, 1) == 1);
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if (kb_input.count == 0) {
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res = -1;
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goto free;
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}
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res = *kb_input.p_head++;
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if (kb_input.p_head == kb_input.buf + KB_INBUF_SIZE)
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kb_input.p_head = kb_input.buf;
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kb_input.count--;
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free:
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xchg(&kb_input.lock, 0);
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return res;
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} |