Miscellaneous utility routines for some fundamental I6 needs.

• §1. Miscellany
• §2. Final Code Dependencies
• §3. Firebreak
• §4. Print Decimal Number
• §5. Print Text
• §6. Print Or Run
• §7. Saying Phrases
• §8. GenerateRandomNumber
• §9. PrintSpaces
• §10. SwapWorkflags
• §11. TestUseOption
• §12. ZRegion
• §13. Arrcpy
• §14. Verbs as Values
• §15. Regarding
• §16. Say One Of
• §17. Rounding
• §18. Doing nothing

§1. Miscellany.

#Iftrue WORDSIZE == 2;
Constant BLOCKV_STACK_SIZE = 224;
#ifnot;
Constant BLOCKV_STACK_SIZE = BasicInformKit`STACK_FRAME_CAPACITY_CFGV / 4;
#endif;

Array blockv_stack --> BLOCKV_STACK_SIZE;
Global I7SFRAME;

Global TEXT_TY_RE_Err = 0;
Global prior_named_noun; for adaptive text generation
Global prior_named_list; ditto: length of list of items
Global prior_named_list_gender; ditto: common gender of list of items, or -1
Global story_tense = 1; ditto: present tense
Global story_viewpoint = 2; ditto: second person singular
Global say__p = 1; Global say__pc = 0; Global say__pc_save = 0;
Global say__n; Global say__comp;
Global los_rv = false;
Global parameter_object; = I7 "parameter-object" = I7 "container in question"
Global parameter_value; not typesafe in I7
Global property_to_be_totalled; used to implement "total P of..."
Global property_loop_sign; \(+1\) for increasing order, \(-1\) for decreasing
Global suppress_scope_loops;
Global temporary_value; can be used anywhere side-effects can't occur
Global clr_fg = 1; foreground colour
Global clr_bg = 1; background colour
Global clr_fgstatus = 1; foreground colour of statusline
Global clr_bgstatus = 1; background colour of statusline
Global clr_on; has colour been enabled by the player?
Global statuswin_current; if writing to top window
Global suppress_text_substitution = false;
Global deadflag = 0;

Global statuswin_cursize = 0;
Global statuswin_size = 1;

Global debug_dialogue = 0;
Global debug_rules = 0;
Global debug_rule_nesting;
Global reason_the_action_failed; = I7 "reason the action failed"
Global indef_mode;                  "Indefinite" mode - ie, "take a brick"
                                    is in this mode

Global standard_interpreter = 0;

Default LanguageCases 1;

§2. Final Code Dependencies. This function definition is a little misleading. The idea is that the final code-generator can inject code of its own into the body here: for example, the final code-generation for Glulx injects code into PLATFORM_SPECIFIC_STARTUP_R to use accelerated VM support for certain veneer functions.

The other three are also misleading, in that final code-generation can add more helpful code here: the fallbacks here are basic.

[ PLATFORM_SPECIFIC_STARTUP_R addr res;
    rfalse;
];

[ DebugAction a anames str;
    if (a >= 4096) print "<fake action ", a-4096, ">"; else print "<action ", a, ">";
];

[ DebugAttribute a anames str;
    print "<attribute ", a, ">";
];

[ DebugProperty p pnames str;
    print "<property ", p, ">";
];

§3. Firebreak.

Array Protect_I7_Arrays --> 16339 12345;

§4. Print Decimal Number. DecimalNumber is a trivial function which just prints a number, in decimal digits. It is left over from the I6 library's support routines for Glulx, where it was intended as a stub to pass to the Glulx Glulx_PrintAnything routine (which I7 does not use). In I7, however, it's also used as the default printing routine for new kinds of value.

[ DecimalNumber num; print num; ];

§5. Print Text. The routine for printing an I7 "text" value, which might be text with or without substitutions.

[ PrintI6Text x;
    if (x ofclass String) print (string) x;
    if (x ofclass Routine) return (x)();
    if (x == EMPTY_TEXT_PACKED) rfalse;
    rtrue;
];
[ I7_String x; TEXT_TY_Say(x); ]; An alternative name now used only by extensions

§6. Print Or Run. This utility remains from the old I6 library: it essentially treats a property as textual and prints it where possible. Where the no_break flag is set, we expect the text to form only a small part of a paragraph, and it's inappropriate to break here: for instance, for printing the "printed name" of an object. Where the flag is clear, however, the text is expected to form its own paragraph.

Where PrintOrRun is used in breaking mode, which is only for a very few properties in I7 (indeed at present only initial and description), the routine called is given the chance to decide whether to print or not. It should return true or false according to whether it did so; this allows us to divide the paragraph or not accordingly.

[ PrintOrRun obj prop no_break  pv st routine_return_value;
    @push self; self = obj;
    if (prop == 0) {
        print (name) prop; routine_return_value = true;
    } else {
        routine_return_value = TEXT_TY_Say(obj.prop);
    }
    @pull self;
    if (routine_return_value) {
        say__p = 1;
        if (no_break == false) {
            new_line;
            DivideParagraphPoint();
        }
    }

    return routine_return_value;
];

[ DA_Number n; print n; ];
[ DA_TruthState n; if (n==0) print "false"; else print "true"; ];

§7. Saying Phrases.

[ SayPhraseName closure;
    if (closure == 0) print "nothing";
    else print (string) closure-->2;
];

§8. GenerateRandomNumber. The following uses the virtual machine's RNG (via the I6 built-in function random) to produce a uniformly random integer in the range \(n\) to \(m\) inclusive, where \(n\) and \(m\) are allowed to be either way around; so that a random number between 17 and 4 is the same thing as a random number between 4 and 17, and there is therefore no pair of \(n\) and \(m\) corresponding to an empty range of values.

The following trick, devised by Zed Lopez in 2023, is designed to work even when the range width (here called \(s\)) is larger than the maximum signed integer size, so that the signed comparison \(s > 0\) fails. In that case, it appears alarmingly to go into an infinite loop, but the loop terminates with a probability of at least 0.5 on each iteration. Even in the worst case of the range, the expected number of iterations is only 2, and the probability of taking more than 50 iterations is less than 0.0000000000000001, which is obviously negligible. But we check the iteration count anyway in case a rigged random number generator is being used, e.g. for story testing purposes, which happens to be biased in a really unlucky way for us.

[ GenerateRandomNumber n m s it;
    if (n==m) return n;
    if (n>m) { s = n; n = m; m = s; }
    n--;
    s = m - n;
    if (s > 0) return random(s) + n;
    n++;
    do {
        s = FullyRandomWord();
        if ((s >= n) && (s <= m)) return s;
        it++;
    } until (it > 50);
    return n;
];
Constant R_DecimalNumber = GenerateRandomNumber;
Constant R_PrintTimeOfDay = GenerateRandomNumber;

§9. PrintSpaces. Which prints a row of \(n\) spaces, for \(n\geq 0\).

[ PrintSpaces n;
    while (n > 0) {
        print " ";
        n = n - 1;
    }
];

§10. SwapWorkflags. Recall that we have two general-purpose temporary attributes for each object: workflag and workflag2. The following swaps their values over for every object at once.

[ SwapWorkflags obj lst;
    objectloop (obj ofclass Object) {
        lst = false;
        if (obj has workflag2) lst = true;
        give obj ~workflag2;
        if (obj has workflag) give obj workflag2;
        give obj ~workflag;
        if (lst) give obj workflag;
    }
];

§11. TestUseOption. This routine, compiled by Inform, returns true if the supplied argument is the number of a use option in force for the current run of Inform, and false otherwise.

§12. ZRegion. I7 contains many relics from I6, but here's a relic from I5: a routine which used to determine the metaclass of a value, before that concept was given a name. In I6 code, it can be implemented simply using metaclass, as the following shows. (The name is from "region of the Z-machine".)

[ ZRegion addr;
    switch (metaclass(addr)) {
        nothing: return 0;
        Object, Class: return 1;
        Routine: return 2;
        String: return 3;
    }
];

§13. Arrcpy. This is not quite so efficient as Memcpy, but not terrible.

[ Arrcpy to_array to_entry_size from_array from_entry_size no_entries  n val;
    if (to_entry_size == from_entry_size)
        Memcpy(to_array, from_array, to_entry_size*no_entries);
    else if ((to_entry_size == 2) && (from_entry_size == 4)) {
        for (n = 0: n<no_entries: n++) {
            val = from_array-->n;
            to_array->0 = (val/256)%256; to_array->1 = val%256;
            to_array = to_array + 2;
        }
    } else "*** Arrcpy doesn't support this ***";
];

§14. Verbs as Values.

[ PrintVerbAsValue vb;
    if (vb == 0) print "(no verb)";
    else { print "verb "; vb(1); }
];

[ VerbIsMeaningful vb;
    if ((vb) && (ComparePV(vb(CV_MEANING), MEANINGLESS_RR) ~= 0)) rtrue;
    rfalse;
];

[ VerbIsModal vb;
    if ((vb) && (vb(CV_MODAL))) rtrue;
    rfalse;
];

§15. Regarding. These are used with adaptive text.

[ RegardingSingleObject obj;
    prior_named_list = 1;
    prior_named_list_gender = -1;
    prior_named_noun = obj;
];

[ RegardingNumber n;
    prior_named_list = n;
    prior_named_list_gender = -1;
    prior_named_noun = nothing;
];

§16. Say One Of. These routines are described in the Extensions chapter of the Inform documentation.

[ I7_SOO_PAR oldval count; if (count <= 1) return count; return random(count); ];
[ I7_SOO_RAN oldval count v; if (count <= 1) return count;
    v = oldval; while (v == oldval) v = random(count); return v; ];
[ I7_SOO_STI oldval count v; if (oldval) return oldval; return I7_SOO_PAR(oldval, count); ];
[ I7_SOO_CYC oldval count; oldval++; if (oldval > count) oldval = 1; return oldval; ];
[ I7_SOO_STOP oldval count; oldval++; if (oldval > count) oldval = count; return oldval; ];
[ I7_SOO_TAP oldval count tn rn c; if (count <= 1) return count; tn = count*(count+1)/2;
    rn = random(tn); for (c=1:c<=count:c++) { rn = rn - c; if (rn<=0) return (count-c+1); } ];
[ I7_SOO_TRAN oldval count; if (oldval<count) return oldval+1;
    return count + 1 + I7_SOO_RAN(oldval%(count+1), count); ];
[ I7_SOO_TPAR oldval count; if (oldval<count) return oldval+1;
    return count + 1 + I7_SOO_PAR(oldval%(count+1), count); ];

Array I7_SOO_SHUF->32;

[ I7_SOO_SHU oldval count sd ct v i j s ssd scope cc base;
    base = count+1;
    v = oldval%base; oldval = oldval/base; ct = oldval%base; sd = oldval/base;
    if (count > 32) return I7_SOO_PAR(oldval, count);
    if (count <= 1) v = count;
    else {
        rint "^In v=", v, " ct=", ct, " sd=", sd, "^";
        cc = base*base;
        scope = (MAX_POSITIVE_NUMBER-1)/cc;
        rint "Scope = ", scope, "^";
        if (sd == 0) { sd = random(scope); ct=0; }
        for (i=0:i<count:i++) I7_SOO_SHUF->i = i;
        ssd = sd;
        for (i=0:i<count-1:i++) {
            j = (sd)%(count-i)+i; sd = (sd*31973)+17; if (sd<0) sd=-sd;
            s = I7_SOO_SHUF->j; I7_SOO_SHUF->j = I7_SOO_SHUF->i; I7_SOO_SHUF->i = s;
        }
        or (i=0:i<count:i++) print I7_SOO_SHUF->i, " "; print "^";
        v = (I7_SOO_SHUF->ct)+1;
        ct++; if (ct >= count) { ct = 0; ssd = 0; }
    }
    rint "Out v=", v, " ct=", ct, " ssd=", sd, "^";
    rint "Return ", v + ct*base + ssd*base*base, "^";
    return v + ct*base + ssd*base*base;
];

§17. Rounding. The following rounds a numerical value t1 to the nearest unit of t2; for instance, if t2 is 5 then it rounds to the nearest 5. The name is an anachronism, as it's used for all kinds of value.

[ RoundOffValue t1 t2;
    if (t1 >= 0) return ((t1+t2/2)/t2)*t2;
    return -((-t1+t2/2)/t2)*t2;
];

§18. Doing nothing. Surprisingly, this function has a use.

[ DoNothing;
    rfalse;
];