Function spellretention

src/spell.c:2294–2336

}

staticfn char *
spellretention(int idx, char * outbuf)
{
    long turnsleft, percent, accuracy;
    int skill;

    skill = P_SKILL(spell_skilltype(spellid(idx)));
    skill = max(skill, P_UNSKILLED); /* restricted same as unskilled */
    turnsleft = spellknow(idx);
    *outbuf = '\0'; /* lint suppression */

    if (turnsleft < 1L) {
        /* spell has expired; hero can't successfully cast it anymore */
        Strcpy(outbuf, "(gone)");
    } else if (turnsleft >= (long) KEEN) {
        /* full retention, first turn or immediately after reading book */
        Strcpy(outbuf, "100%");
    } else {
        /*
         * Retention is displayed as a range of percentages of
         * amount of time left until memory of the spell expires;
         * the precision of the range depends upon hero's skill
         * in this spell.
         *    expert:  2% intervals; 1-2,   3-4,  ...,   99-100;
         *   skilled:  5% intervals; 1-5,   6-10, ...,   95-100;
         *     basic: 10% intervals; 1-10, 11-20, ...,   91-100;
         * unskilled: 25% intervals; 1-25, 26-50, 51-75, 76-100.
         *
         * At the low end of each range, a value of N% really means
         * (N-1)%+1 through N%; so 1% is "greater than 0, at most 200".
         * KEEN is a multiple of 100; KEEN/100 loses no precision.
         */
        percent = (turnsleft - 1L) / ((long) KEEN / 100L) + 1L;
        accuracy = (skill == P_EXPERT) ? 2L
                   : (skill == P_SKILLED) ? 5L
                     : (skill == P_BASIC) ? 10L
                       : 25L;
        /* round up to the high end of this range */
        percent = accuracy * ((percent - 1L) / accuracy + 1L);
        Sprintf(outbuf, "%ld%%-%ld%%", percent - accuracy + 1L, percent);
    }
    return outbuf;
}

/* Learn a spell during creation of the initial inventory */
void