LddRot13ProcIrq < Training2

%SECTION0{name=LddRot13ProcIrq}% Proc, workqueue, Irq  

---++ Task:

Write a small module that creates a proc entry that can be read or written. Text written is rot13 scrambled and can be read back with the same proc entry.

   * Processing shall not be done within the proc write function, but delayed with a workqueue

   * Take care of race conditions!

   * No buffering etc. required; only the last written text can be read back.

---++ Tips:

   * rot algorithm:

<verbatim>
static void rot_buf(char *buf, int rotate)
{
        int x;

        for (x=0; buf[x] != '\0'; x++) {
                if (islower (buf[x]))
                        buf[x] = ((buf[x] + rotate - 'a') % 26) + 'a';
                else if (isupper (buf[x]))
                        buf[x] = ((buf[x] + rotate - 'A') % 26) + 'A';
                else if (isdigit (buf[x]))
                        buf[x] = ((buf[x] + rotate - '0') % 10) + '0';
        }
}
</verbatim>

   * c library functions: =include/linux/ctype.h=
5.7.9. Porting of Linux		1. Denx Training Topics
Prev		Home