Liren Large Software Subsidy 7/07.iso/c/c070/4.ddi/TOOLS.4/TCTSRC1.EXE/KBSTUFF.C

C/C++ Source or Header | 1989-03-31 | 4.6 KB | 161 lines

/**
*
* Name        KBSTUFF -- Force a string into the BIOS type-ahead
*               buffer.
*
* Synopsis    premain = kbstuff (where, pstring);
*
*        char *premain      Pointer to first character in string
*                  NOT inserted in queue, or to the
*                  trailing NUL ('\0') if they were all
*                  placed in the queue.
*
*        int where      KB_HEAD if string to be placed at head
*                  of queue, KB_TAIL if at tail.
*
*        char *pstring      Pointer to first character in string.
*                  String must be terminated by NUL ('\0').
*
* Description    This function forces a string of keystrokes into the
*        BIOS type-ahead queue as if they were typed by the
*        operator.  The string may be inserted at the tail of
*        the queue (as if most recently typed) or at the head
*        (least recently typed).
*
*        If characters in the string are to be placed at the
*        tail of the queue, then as many as possible are
*        inserted and the value of the function is returned
*        as a pointer to the first character NOT inserted.
*
*        If the string is to be placed at the head of the
*        queue, then characters are inserted into the queue if
*        and only if they all fit.  (Therefore no string
*        longer than 15 characters may be placed at the head
*        of the queue.)
*
*        The BIOS keyboard buffer is arranged as a circular
*        queue of fifteen pairs of bytes (plus one pair for
*        overhead).  For extended key sequences the character
*        value is 0 and the scan code is as described in the
*        IBM Technical Reference.  For ASCII characters, on the
*        other hand, the first byte of the pair is the ASCII
*        code for the character and the second is the
*        keystroke's scan code (if the key was generated by a
*        normal scan code) or 0 (if the key was generated by ALT
*        plus the numeric ASCII code on the numeric keypad).
*        For instance,
*
*            pressing 'A' generates character 65, scan code 30,
*
*        but
*
*            pressing ALT + 65 generates character 65, scan
*            code 0.
*
*        (Virtually all application programs treat those two
*        cases identically.)
*
*        For ordinary ASCII characters in the string, this
*        function inserts 0 as the scan code.
*
*        To indicate extended key sequences in the string, use
*        the character '\377' followed by the scan code.  This
*        function will insert 0 as the character value followed
*        by the scan code.
*
* Returns    premain       Pointer to first character in string
*                  NOT inserted in queue, or to the
*                  trailing NUL ('\0') if they were all
*                  placed in the queue.
*
* Version    6.00 (C)Copyright Blaise Computing Inc.  1986-1989
*
**/


#include <bkeybrd.h>
#include <butil.h>

#define EXT_FLAG ((char) '\377') /* Indicates scan code of           */
                 /* extended key sequence.         */

char *kbstuff(where,pstring)
int  where;
char *pstring;
{
    int       length,i;
    register int  j;
    register char *ptr;
    char      *pend;
    int       ints_were_on;
    int       total_size;
    char      value,scan;

    if (where == KB_TAIL)
    {                    /* Stuff at tail of queue.  */
    ints_were_on = utintoff();    /* Turn interrupts off.     */
    for (; *pstring; pstring++)
    {
        if (*pstring == EXT_FLAG)
        {
        value = '\0';
        scan  = *++pstring;
        }
        else
        {
        value = *pstring;
        scan  = '\0';
        }
        if (kbplace(where,value,scan))    /* Try to stuff it. */
        break;            /* Quit if it didn't fit.   */
    }
    }
    else
    {                    /* Stuff at head of queue.  */
    length = 0;
    for (ptr = pstring; *ptr; ptr++)
    {                /* Measure length of string.*/
        length++;
        if (*ptr == EXT_FLAG)
        ptr++;
    }
    pend = ptr;            /* Pointer to end of string.*/

    ints_were_on = utintoff();    /* Turn interrupts off.     */

    if (length <= kbqueue(&total_size))
    {                /* The string fits.        */
        for (i = length; i; i--)    /* Stuff each character in  */
        {                /* reverse order.        */
        ptr = pstring;
        for (j = 1; j < i; j++)
        {            /* Step past first (i-1)    */
                    /* characters in string.    */
            if (*ptr == EXT_FLAG)
            ptr++;
            ptr++;
        }
                    /* Now ptr points to i-th   */
                    /* character in string.     */
        if (*ptr == EXT_FLAG)
            kbplace(where,
                (char) 0,
                *(ptr + 1));    /* Scan code only.  */
        else
            kbplace(where,
                *ptr,        /* Character only.  */
                (char) 0);
        }
        pstring = pend;        /* All characters stuffed.  */
    }
    else
    {
        /* Do nothing. */        /* String too big:  No        */
    }                /* characters stuffed.        */
    }

    if (ints_were_on)
    utinton();        /* Turn interrupts back on.        */
    return pstring;        /* Return remainder of string.        */
}