1 files changed, 199 insertions, 0 deletions
diff --git a/kernel/console.c b/kernel/console.c
new file mode 100644
index 0000000..87a83ff
--- /dev/null
+++ b/kernel/console.c
@@ -0,0 +1,199 @@
+//
+// 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 C(x)  ((x)-'@')  // Control-x
+
+//
+// send one character to the uart.
+//
+void
+consputc(int c)
+{
+  extern volatile int panicked; // from printf.c
+
+  if(panicked){
+    for(;;)
+      ;
+  }
+
+  if(c == BACKSPACE){
+    // if the user typed backspace, overwrite with a space.
+    uartputc('\b'); uartputc(' '); uartputc('\b');
+  } else {
+    uartputc(c);
+  }
+}
+
+struct {
+  struct spinlock lock;
+  
+  // input
+#define INPUT_BUF 128
+  char buf[INPUT_BUF];
+  uint r;  // Read index
+  uint w;  // Write index
+  uint e;  // Edit index
+} cons;
+
+//
+// user write()s to the console go here.
+//
+int
+consolewrite(int user_src, uint64 src, int n)
+{
+  int i;
+
+  acquire(&cons.lock);
+  for(i = 0; i < n; i++){
+    char c;
+    if(either_copyin(&c, user_src, src+i, 1) == -1)
+      break;
+    consputc(c);
+  }
+  release(&cons.lock);
+
+  return n;
+}
+
+//
+// user read()s from the console go here.
+// copy (up to) a whole input line to dst.
+// user_dist indicates whether dst is a user
+// or kernel address.
+//
+int
+consoleread(int user_dst, uint64 dst, int n)
+{
+  uint target;
+  int c;
+  char cbuf;
+
+  target = n;
+  acquire(&cons.lock);
+  while(n > 0){
+    // wait until interrupt handler has put some
+    // input into cons.buffer.
+    while(cons.r == cons.w){
+      if(myproc()->killed){
+        release(&cons.lock);
+        return -1;
+      }
+      sleep(&cons.r, &cons.lock);
+    }
+
+    c = cons.buf[cons.r++ % INPUT_BUF];
+
+    if(c == C('D')){  // end-of-file
+      if(n < target){
+        // Save ^D for next time, to make sure
+        // caller gets a 0-byte result.
+        cons.r--;
+      }
+      break;
+    }
+
+    // copy the input byte to the user-space buffer.
+    cbuf = c;
+    if(either_copyout(user_dst, dst, &cbuf, 1) == -1)
+      break;
+
+    dst++;
+    --n;
+
+    if(c == '\n'){
+      // a whole line has arrived, return to
+      // the user-level read().
+      break;
+    }
+  }
+  release(&cons.lock);
+
+  return target - n;
+}
+
+//
+// the console input interrupt handler.
+// uartintr() calls this for input character.
+// do erase/kill processing, append to cons.buf,
+// wake up consoleread() if a whole line has arrived.
+//
+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] != '\n'){
+      cons.e--;
+      consputc(BACKSPACE);
+    }
+    break;
+  case C('H'): // Backspace
+  case '\x7f':
+    if(cons.e != cons.w){
+      cons.e--;
+      consputc(BACKSPACE);
+    }
+    break;
+  default:
+    if(c != 0 && cons.e-cons.r < INPUT_BUF){
+      c = (c == '\r') ? '\n' : c;
+
+      // echo back to the user.
+      consputc(c);
+
+      // store for consumption by consoleread().
+      cons.buf[cons.e++ % INPUT_BUF] = c;
+
+      if(c == '\n' || c == C('D') || cons.e == cons.r+INPUT_BUF){
+        // wake up consoleread() if a whole line (or end-of-file)
+        // has arrived.
+        cons.w = cons.e;
+        wakeup(&cons.r);
+      }
+    }
+    break;
+  }
+  
+  release(&cons.lock);
+}
+
+void
+consoleinit(void)
+{
+  initlock(&cons.lock, "cons");
+
+  uartinit();
+
+  // connect read and write system calls
+  // to consoleread and consolewrite.
+  devsw[CONSOLE].read = consoleread;
+  devsw[CONSOLE].write = consolewrite;
+}