\n"
" \n"
- // Has the location been set yet?
+ // Initialise the current location if it is not set
+ // (all general registers are initially 0).
" if (g1 eq 0)\n"
- " {\n"
- // Initialise the current location to first button on
- // this menu.
- " g1 = " << location_bias << ";\n"
- " }\n"
- " else\n"
- " {\n"
- // Has the user selected a link?
- " if (g0 ne 0)\n"
- " {\n"
- // First update the history.
- // Does link go to the last page in the history?
- " if (((g0 ^ g2) & " << menu_mask
- << ") == 0)\n"
- // It does; we treat this as going back and pop the old
- // location off the history stack into the current
- // location. Clear the free stack slot.
- " {\n"
- " g1 = g2; g2 = g3; g3 = g4; g4 = g5;\n"
- " g5 = g6; g6 = g7; g7 = g8; g8 = g9;\n"
- " g9 = g10; g10 = g11; g11 = 0;\n"
- " }\n"
- " else\n"
- // Link goes to some other page, so push current
- // location onto the history stack and set the current
- // location to be exactly the target location.
- " {\n"
- " g11 = g10; g10 = g9; g9 = g8; g8 = g7;\n"
- " g7 = g6; g6 = g5; g5 = g4; g4 = g3;\n"
- " g3 = g2; g2 = g1; g1 = g0;\n"
- " }\n"
- " }\n"
- // Find the target page number.
- " g0 = g1 & " << menu_mask << ";\n";
- // There seems to be no way to perform a computed jump,
- // so we generate all possible jumps and a binary search
- // to select the correct one.
- generate_menu_dispatch(file, 12,
- 0, contents_.menus.size() - 1);
- file <<
- " }\n";
+ " g1 = " << 1 + button_mult << ";\n";
}
- else // menu_num != 0
+ else
{
file <<
" \n"
" \n";
}
+ // When a title finishes or the user presses the menu
+ // button, this always jumps to the titleset's root menu.
+ // We want to return the user to the last menu they used.
+ // So we arrange for each titleset's root menu to return
+ // to the vmgm title menu and then dispatch from there to
+ // whatever the correct menu is. We determine the correct
+ // menu by looking at the menu part of g1.
+
+ file << " g0 = g1 & " << menu_mask << ";\n";
+
+ // There is a limit of 128 VM instructions in each PGC.
+ // Therefore in each menu's section we generate
+ // jumps to menus with numbers greater by 512, 256, 128,
+ // ..., 1 where (a) such a menu exists, (b) this menu
+ // number is divisible by twice that increment and (c) the
+ // correct menu is that or a later menu. Thus each menu
+ // has at most 10 such conditional jumps and is reachable
+ // by at most 10 jumps from the title menu. This chain of
+ // jumps might take too long on some players; this has yet
+ // to be investigated.
+
+ for (std::size_t menu_incr = (menu_mask + 1) / 2;
+ menu_incr != 0;
+ menu_incr /= 2)
+ {
+ if (menu_num + menu_incr < contents_.menus.size()
+ && (menu_num & (menu_incr * 2 - 1)) == 0)
+ {
+ file <<
+ " if (g0 ge " << 1 + menu_num + menu_incr
+ << ")\n"
+ " jump menu " << 1 + menu_num + menu_incr
+ << ";\n";
+ }
+ }
+
file <<
- // Clear link indicator and highlight the
- // appropriate link/button.
- " g0 = 0; s8 = g1 & " << button_mask << ";\n"
+ // Highlight the appropriate button.
+ " s8 = g1 & " << button_mask << ";\n"
"
\n"
- " \n";
+ " \n";
for (std::size_t button_num = 0;
button_num != menu.entries.size();
++button_num)
{
- file << "