467 lines
13 KiB
C
467 lines
13 KiB
C
#include <defs.h>
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#include <x86.h>
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#include <stdio.h>
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#include <string.h>
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#include <kbdreg.h>
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#include <picirq.h>
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#include <trap.h>
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/* stupid I/O delay routine necessitated by historical PC design flaws */
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static void
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delay(void) {
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inb(0x84);
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inb(0x84);
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inb(0x84);
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inb(0x84);
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}
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/***** Serial I/O code *****/
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#define COM1 0x3F8
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#define COM_RX 0 // In: Receive buffer (DLAB=0)
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#define COM_TX 0 // Out: Transmit buffer (DLAB=0)
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#define COM_DLL 0 // Out: Divisor Latch Low (DLAB=1)
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#define COM_DLM 1 // Out: Divisor Latch High (DLAB=1)
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#define COM_IER 1 // Out: Interrupt Enable Register
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#define COM_IER_RDI 0x01 // Enable receiver data interrupt
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#define COM_IIR 2 // In: Interrupt ID Register
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#define COM_FCR 2 // Out: FIFO Control Register
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#define COM_LCR 3 // Out: Line Control Register
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#define COM_LCR_DLAB 0x80 // Divisor latch access bit
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#define COM_LCR_WLEN8 0x03 // Wordlength: 8 bits
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#define COM_MCR 4 // Out: Modem Control Register
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#define COM_MCR_RTS 0x02 // RTS complement
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#define COM_MCR_DTR 0x01 // DTR complement
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#define COM_MCR_OUT2 0x08 // Out2 complement
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#define COM_LSR 5 // In: Line Status Register
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#define COM_LSR_DATA 0x01 // Data available
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#define COM_LSR_TXRDY 0x20 // Transmit buffer avail
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#define COM_LSR_TSRE 0x40 // Transmitter off
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#define MONO_BASE 0x3B4
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#define MONO_BUF 0xB0000
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#define CGA_BASE 0x3D4
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#define CGA_BUF 0xB8000
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#define CRT_ROWS 25
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#define CRT_COLS 80
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#define CRT_SIZE (CRT_ROWS * CRT_COLS)
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#define LPTPORT 0x378
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static uint16_t *crt_buf;
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static uint16_t crt_pos;
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static uint16_t addr_6845;
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// 显示器初始化，CGA 是 Color Graphics Adapter 的缩写
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// CGA显存按照下面的方式映射：
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// -- 0xB0000 - 0xB7777 单色字符模式
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// -- 0xB8000 - 0xBFFFF 彩色字符模式及 CGA 兼容图形模式
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// 6845芯片是IBM PC中的视频控制器
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// CPU通过IO地址0x3B4-0x3B5来驱动6845控制单色显示，通过IO地址0x3D4-0x3D5来控制彩色显示。
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// -- 数据寄存器 映射 到 端口 0x3D5或0x3B5
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// -- 索引寄存器 0x3D4或0x3B4,决定在数据寄存器中的数据表示什么。
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/* TEXT-mode CGA/VGA display output */
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static void
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cga_init(void) {
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volatile uint16_t *cp = (uint16_t *)CGA_BUF; //CGA_BUF: 0xB8000 (彩色显示的显存物理基址)
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uint16_t was = *cp; //保存当前显存0xB8000处的值
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*cp = (uint16_t) 0xA55A; // 给这个地址随便写个值，看看能否再读出同样的值
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if (*cp != 0xA55A) { // 如果读不出来，说明没有这块显存，即是单显配置
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cp = (uint16_t*)MONO_BUF; //设置为单显的显存基址 MONO_BUF： 0xB0000
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addr_6845 = MONO_BASE; //设置为单显控制的IO地址，MONO_BASE: 0x3B4
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} else { // 如果读出来了，有这块显存，即是彩显配置
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*cp = was; //还原原来显存位置的值
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addr_6845 = CGA_BASE; // 设置为彩显控制的IO地址，CGA_BASE: 0x3D4
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}
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// Extract cursor location
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// 6845索引寄存器的index 0x0E（及十进制的14）== 光标位置(高位)
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// 6845索引寄存器的index 0x0F（及十进制的15）== 光标位置(低位)
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// 6845 reg 15 : Cursor Address (Low Byte)
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uint32_t pos;
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outb(addr_6845, 14);
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pos = inb(addr_6845 + 1) << 8; //读出了光标位置(高位)
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outb(addr_6845, 15);
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pos |= inb(addr_6845 + 1); //读出了光标位置(低位)
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crt_buf = (uint16_t*) cp; //crt_buf是CGA显存起始地址
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crt_pos = pos; //crt_pos是CGA当前光标位置
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}
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static bool serial_exists = 0;
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static void
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serial_init(void) {
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// Turn off the FIFO
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outb(COM1 + COM_FCR, 0);
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// Set speed; requires DLAB latch
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outb(COM1 + COM_LCR, COM_LCR_DLAB);
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outb(COM1 + COM_DLL, (uint8_t) (115200 / 9600));
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outb(COM1 + COM_DLM, 0);
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// 8 data bits, 1 stop bit, parity off; turn off DLAB latch
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outb(COM1 + COM_LCR, COM_LCR_WLEN8 & ~COM_LCR_DLAB);
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// No modem controls
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outb(COM1 + COM_MCR, 0);
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// Enable rcv interrupts
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outb(COM1 + COM_IER, COM_IER_RDI);
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// Clear any preexisting overrun indications and interrupts
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// Serial port doesn't exist if COM_LSR returns 0xFF
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serial_exists = (inb(COM1 + COM_LSR) != 0xFF);
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(void) inb(COM1+COM_IIR);
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(void) inb(COM1+COM_RX);
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if (serial_exists) {
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pic_enable(IRQ_COM1);
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}
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}
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static void
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lpt_putc_sub(int c) {
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int i;
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for (i = 0; !(inb(LPTPORT + 1) & 0x80) && i < 12800; i ++) {
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delay();
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}
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outb(LPTPORT + 0, c);
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outb(LPTPORT + 2, 0x08 | 0x04 | 0x01);
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outb(LPTPORT + 2, 0x08);
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}
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/* lpt_putc - copy console output to parallel port */
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static void
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lpt_putc(int c) {
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if (c != '\b') {
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lpt_putc_sub(c);
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}
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else {
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lpt_putc_sub('\b');
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lpt_putc_sub(' ');
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lpt_putc_sub('\b');
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}
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}
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/* cga_putc - print character to console */
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static void
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cga_putc(int c) {
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// set black on white
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if (!(c & ~0xFF)) {
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c |= 0x0700;
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}
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switch (c & 0xff) {
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case '\b':
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if (crt_pos > 0) {
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crt_pos --;
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crt_buf[crt_pos] = (c & ~0xff) | ' ';
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}
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break;
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case '\n':
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crt_pos += CRT_COLS;
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case '\r':
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crt_pos -= (crt_pos % CRT_COLS);
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break;
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default:
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crt_buf[crt_pos ++] = c; // write the character
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break;
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}
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// What is the purpose of this?
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if (crt_pos >= CRT_SIZE) {
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int i;
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memmove(crt_buf, crt_buf + CRT_COLS, (CRT_SIZE - CRT_COLS) * sizeof(uint16_t));
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for (i = CRT_SIZE - CRT_COLS; i < CRT_SIZE; i ++) {
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crt_buf[i] = 0x0700 | ' ';
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}
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crt_pos -= CRT_COLS;
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}
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// move that little blinky thing
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outb(addr_6845, 14);
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outb(addr_6845 + 1, crt_pos >> 8);
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outb(addr_6845, 15);
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outb(addr_6845 + 1, crt_pos);
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}
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static void
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serial_putc_sub(int c) {
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int i;
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for (i = 0; !(inb(COM1 + COM_LSR) & COM_LSR_TXRDY) && i < 12800; i ++) {
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delay();
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}
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outb(COM1 + COM_TX, c);
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}
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/* serial_putc - print character to serial port */
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static void
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serial_putc(int c) {
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if (c != '\b') {
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serial_putc_sub(c);
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}
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else {
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serial_putc_sub('\b');
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serial_putc_sub(' ');
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serial_putc_sub('\b');
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}
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}
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/* *
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* Here we manage the console input buffer, where we stash characters
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* received from the keyboard or serial port whenever the corresponding
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* interrupt occurs.
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* */
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#define CONSBUFSIZE 512
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static struct {
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uint8_t buf[CONSBUFSIZE];
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uint32_t rpos;
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uint32_t wpos;
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} cons;
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/* *
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* cons_intr - called by device interrupt routines to feed input
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* characters into the circular console input buffer.
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* */
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static void
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cons_intr(int (*proc)(void)) {
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int c;
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while ((c = (*proc)()) != -1) {
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if (c != 0) {
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cons.buf[cons.wpos ++] = c;
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if (cons.wpos == CONSBUFSIZE) {
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cons.wpos = 0;
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}
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}
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}
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}
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/* serial_proc_data - get data from serial port */
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static int
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serial_proc_data(void) {
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if (!(inb(COM1 + COM_LSR) & COM_LSR_DATA)) {
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return -1;
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}
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int c = inb(COM1 + COM_RX);
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if (c == 127) {
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c = '\b';
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}
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return c;
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}
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/* serial_intr - try to feed input characters from serial port */
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void
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serial_intr(void) {
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if (serial_exists) {
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cons_intr(serial_proc_data);
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}
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}
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/***** Keyboard input code *****/
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#define NO 0
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#define SHIFT (1<<0)
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#define CTL (1<<1)
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#define ALT (1<<2)
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#define CAPSLOCK (1<<3)
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#define NUMLOCK (1<<4)
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#define SCROLLLOCK (1<<5)
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#define E0ESC (1<<6)
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static uint8_t shiftcode[256] = {
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[0x1D] CTL,
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[0x2A] SHIFT,
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[0x36] SHIFT,
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[0x38] ALT,
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[0x9D] CTL,
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[0xB8] ALT
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};
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static uint8_t togglecode[256] = {
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[0x3A] CAPSLOCK,
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[0x45] NUMLOCK,
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[0x46] SCROLLLOCK
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};
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static uint8_t normalmap[256] = {
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NO, 0x1B, '1', '2', '3', '4', '5', '6', // 0x00
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'7', '8', '9', '0', '-', '=', '\b', '\t',
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'q', 'w', 'e', 'r', 't', 'y', 'u', 'i', // 0x10
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'o', 'p', '[', ']', '\n', NO, 'a', 's',
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'd', 'f', 'g', 'h', 'j', 'k', 'l', ';', // 0x20
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'\'', '`', NO, '\\', 'z', 'x', 'c', 'v',
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'b', 'n', 'm', ',', '.', '/', NO, '*', // 0x30
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NO, ' ', NO, NO, NO, NO, NO, NO,
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NO, NO, NO, NO, NO, NO, NO, '7', // 0x40
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'8', '9', '-', '4', '5', '6', '+', '1',
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'2', '3', '0', '.', NO, NO, NO, NO, // 0x50
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[0xC7] KEY_HOME, [0x9C] '\n' /*KP_Enter*/,
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[0xB5] '/' /*KP_Div*/, [0xC8] KEY_UP,
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[0xC9] KEY_PGUP, [0xCB] KEY_LF,
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[0xCD] KEY_RT, [0xCF] KEY_END,
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[0xD0] KEY_DN, [0xD1] KEY_PGDN,
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[0xD2] KEY_INS, [0xD3] KEY_DEL
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};
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static uint8_t shiftmap[256] = {
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NO, 033, '!', '@', '#', '$', '%', '^', // 0x00
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'&', '*', '(', ')', '_', '+', '\b', '\t',
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'Q', 'W', 'E', 'R', 'T', 'Y', 'U', 'I', // 0x10
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'O', 'P', '{', '}', '\n', NO, 'A', 'S',
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'D', 'F', 'G', 'H', 'J', 'K', 'L', ':', // 0x20
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'"', '~', NO, '|', 'Z', 'X', 'C', 'V',
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'B', 'N', 'M', '<', '>', '?', NO, '*', // 0x30
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NO, ' ', NO, NO, NO, NO, NO, NO,
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NO, NO, NO, NO, NO, NO, NO, '7', // 0x40
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'8', '9', '-', '4', '5', '6', '+', '1',
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'2', '3', '0', '.', NO, NO, NO, NO, // 0x50
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[0xC7] KEY_HOME, [0x9C] '\n' /*KP_Enter*/,
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[0xB5] '/' /*KP_Div*/, [0xC8] KEY_UP,
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[0xC9] KEY_PGUP, [0xCB] KEY_LF,
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[0xCD] KEY_RT, [0xCF] KEY_END,
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[0xD0] KEY_DN, [0xD1] KEY_PGDN,
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[0xD2] KEY_INS, [0xD3] KEY_DEL
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};
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#define C(x) (x - '@')
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static uint8_t ctlmap[256] = {
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NO, NO, NO, NO, NO, NO, NO, NO,
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NO, NO, NO, NO, NO, NO, NO, NO,
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C('Q'), C('W'), C('E'), C('R'), C('T'), C('Y'), C('U'), C('I'),
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C('O'), C('P'), NO, NO, '\r', NO, C('A'), C('S'),
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C('D'), C('F'), C('G'), C('H'), C('J'), C('K'), C('L'), NO,
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NO, NO, NO, C('\\'), C('Z'), C('X'), C('C'), C('V'),
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C('B'), C('N'), C('M'), NO, NO, C('/'), NO, NO,
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[0x97] KEY_HOME,
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[0xB5] C('/'), [0xC8] KEY_UP,
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[0xC9] KEY_PGUP, [0xCB] KEY_LF,
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[0xCD] KEY_RT, [0xCF] KEY_END,
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[0xD0] KEY_DN, [0xD1] KEY_PGDN,
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[0xD2] KEY_INS, [0xD3] KEY_DEL
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};
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static uint8_t *charcode[4] = {
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normalmap,
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shiftmap,
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ctlmap,
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ctlmap
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};
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/* *
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* kbd_proc_data - get data from keyboard
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*
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* The kbd_proc_data() function gets data from the keyboard.
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* If we finish a character, return it, else 0. And return -1 if no data.
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* */
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static int
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kbd_proc_data(void) {
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int c;
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uint8_t data;
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static uint32_t shift;
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if ((inb(KBSTATP) & KBS_DIB) == 0) {
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return -1;
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}
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data = inb(KBDATAP);
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if (data == 0xE0) {
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// E0 escape character
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shift |= E0ESC;
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return 0;
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} else if (data & 0x80) {
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// Key released
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data = (shift & E0ESC ? data : data & 0x7F);
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shift &= ~(shiftcode[data] | E0ESC);
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return 0;
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} else if (shift & E0ESC) {
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// Last character was an E0 escape; or with 0x80
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data |= 0x80;
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shift &= ~E0ESC;
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}
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shift |= shiftcode[data];
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shift ^= togglecode[data];
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c = charcode[shift & (CTL | SHIFT)][data];
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if (shift & CAPSLOCK) {
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if ('a' <= c && c <= 'z')
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c += 'A' - 'a';
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else if ('A' <= c && c <= 'Z')
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c += 'a' - 'A';
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}
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// Process special keys
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// Ctrl-Alt-Del: reboot
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if (!(~shift & (CTL | ALT)) && c == KEY_DEL) {
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cprintf("Rebooting!\n");
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outb(0x92, 0x3); // courtesy of Chris Frost
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}
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return c;
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}
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/* kbd_intr - try to feed input characters from keyboard */
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static void
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kbd_intr(void) {
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cons_intr(kbd_proc_data);
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}
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static void
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kbd_init(void) {
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// drain the kbd buffer
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kbd_intr();
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pic_enable(IRQ_KBD);
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}
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/* cons_init - initializes the console devices */
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void
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cons_init(void) {
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cga_init();
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serial_init();
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kbd_init();
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if (!serial_exists) {
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cprintf("serial port does not exist!!\n");
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}
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}
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/* cons_putc - print a single character @c to console devices */
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void
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cons_putc(int c) {
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lpt_putc(c);
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cga_putc(c);
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serial_putc(c);
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}
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/* *
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* cons_getc - return the next input character from console,
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* or 0 if none waiting.
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* */
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int
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cons_getc(void) {
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int c;
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// poll for any pending input characters,
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// so that this function works even when interrupts are disabled
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// (e.g., when called from the kernel monitor).
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serial_intr();
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kbd_intr();
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// grab the next character from the input buffer.
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if (cons.rpos != cons.wpos) {
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c = cons.buf[cons.rpos ++];
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if (cons.rpos == CONSBUFSIZE) {
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cons.rpos = 0;
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}
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return c;
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}
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return 0;
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}
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