xv6-riscv/kernel/console.c
2023-10-16 17:28:59 -06:00

88 lines
1.8 KiB
C

//
// Console input and output, to the uart.
// Reads are line at a time.
// Implements special input characters:
// newline -- end of line
// control-h -- backspace
// control-u -- kill line
// control-d -- end of file
// control-p -- print process list
//
#include <stdarg.h>
#include "types.h"
#include "param.h"
#include "spinlock.h"
#include "sleeplock.h"
#include "fs.h"
#include "file.h"
#include "memlayout.h"
#include "riscv.h"
#include "defs.h"
#include "proc.h"
#define BACKSPACE 0x100
#define INPUT_BUF_SIZE 128
#define C(x) ((x)-'@') // Control-x
struct console {
struct spinlock lock;
// input
char buf[INPUT_BUF_SIZE];
uint r; // Read index
uint w; // Write index
uint e; // Edit index
};
extern struct console cons;
void consputc(int c);
int consolewrite(int user_src, uint64 src, int n);
int consoleread(int user_dst, uint64 dst, int n);
void consoleintr(int c)
{
acquire(&cons.lock);
switch(c){
case C('P'): // Print process list.
procdump();
break;
case C('U'): // Kill line.
while(cons.e != cons.w &&
cons.buf[(cons.e-1) % INPUT_BUF_SIZE] != '\n'){
cons.e--;
consputc(BACKSPACE);
}
break;
case C('H'): // Backspace
case '\x7f': // Delete key
if(cons.e != cons.w){
cons.e--;
consputc(BACKSPACE);
}
break;
default:
if(c != 0 && cons.e-cons.r < INPUT_BUF_SIZE){
c = (c == '\r') ? '\n' : c;
// echo back to the user.
consputc(c);
// store for consumption by consoleread().
cons.buf[cons.e++ % INPUT_BUF_SIZE] = c;
if(c == '\n' || c == C('D') || cons.e-cons.r == INPUT_BUF_SIZE){
// wake up consoleread() if a whole line (or end-of-file)
// has arrived.
cons.w = cons.e;
wakeup(&cons.r);
}
}
break;
}
release(&cons.lock);
}