Restrict Espers by Character

I modified this patch to use quite a bit less space. It uses a bitmask for which characters equip espers similar to way the equipment does, instead of a bunch of jump tables.

Code:

hirom   ; Don't change this.
header  ; Comment out if your ROM has no header.

; Restricts espers to be equippable only by certain characters set in the tables at the bottom.
; All locations have only been tested in FF3us ROM version 1.0, although it should work in version 1.1.
; This will likely not work in the Japanese version.
; Uses 138 bytes of free space at the end of bank C3.
; Address range utilized: C3/F091 to C3/F11A

; Loads the skills menu and gets the character ID. We interrupt this routine in order
; to store the character ID in $1CF8 (formerly Bushido names in the Japanese version;
; unused in FF3us).
; This is why it likely won't work in FF3j, although I suppose you could just find
; another unused location.

org $C31B61
JSR StChr

; Checks if any espers are already equipped. We come here just to create a label for
; ease of use and readability.

org $C35576
ChkEq:

; Sets text color to blue. This block is only executed if the esper is in question is
; already equipped by someone else.

org $C35593
LDA #$2C        ; #$2C for grey text with a blue shadow/#$24 for blue

; Sets text color of the current esper to be printed. As above, we only come here to
; create a label. If an esper can't be equipped because a character can't use it, the
; text will be gray. If an esper can't be equipped because someone else already has it,
; the text will be blue. Otherwise, it'll be white.
; The game will later use the text color to determine whether to allow a character to
; use a particular esper.

org $C35595
SetTxtColor:

; This prints out the name of the person currently using the esper you're trying to
; equip, which was originally the only thing stopping someone from equipping a certain
; esper. We need to change this, as the name will be blank if the character simply
; can't equip it.

org $C355B2
JSR Uneq

; The following lines originally jumped to the subroutine for checking if espers were
; already equipped (C3/5574). This check obviously isn't necessary if the character is
; unable to equip the esper anyway.

org $C35524
JSR ChkEsp

org $C358E1
JSR ChkEsp

org $C359B1
JSR ChkEsp

; Checks if the text color is gray, and BZZTs the character if it is. Since we're also
; using blue to indicate an unequippable esper, we'll simply change the comparison from
; "if not gray, branch" to "if white, branch"

org $C358E8
CMP #$20
BEQ WhiteTxt

; Actions to perform if selecting anything in white text. We come here only to make
; a label

org $C35902
WhiteTxt:

; Custom functions follow.

org $C3F091         ; Start of free space in bank C3.
StChr:                ; Gets the ID of the current character and stores it for later use.
TAX
LDA $69,X
STA $1CF8
RTS

ChkEsp:                ; Checks if a character can use an esper before checking if someone else has it equipped.
PHX                    ; Preserve X. May or may not be necessary, but better safe than sorry.
PHP
STA $E0                ; Stores the esper ID for later use. Could use the stack, but the esper ID needs to go into $E0 anyway.
ASL
TAX
REP #$20
LDA EsperTable,X    ; Get esper equip bitmask
SEP #$10
LDX $1CF8            ; Character ID, from above.
AND $C39C67,X        ; AND with 2^X
BEQ NoEq

Eq:
PLP
PLX
JMP ChkEq

NoEq:
PLP
PLX
LDA #$28            ; Grey text color
JMP SetTxtColor

; Handles error messages in the case of trying to equip a grey esper.

Uneq:
LDA $1602,X            ; Character's name.
CMP #$80            ; If the first letter isn't blank, then someone has the esper equipped and we can go back to tell the player as much.
BCS Exit
PLX                    ; Else, the character can't equip the esper at all and we need to tell the player as much.
LDX $00                

; Above: PLX because we no longer need to RTS to where this subroutine was called from.
; Sloppy, I know. BCS alone (instead of branching to an RTS) won't work because the branch is just too long.
; I'm looking for a way to streamline it.
; LDX $00 because it's necessary anyway as a counter for the next block.

; The following is identical to the code that prints "<Char> has it!",
; just altered slightly so it reads "Can't equip!"

LoadNoEqTxt:
LDA NoEqTxt,X
BEQ Null            ; If the character (letter) being written is null ($00), end the line.
STA $2180            ; Print the current letter.
INX                    ; Go to the next letter.
BRA LoadNoEqTxt
Exit:
RTS

Null:
STZ $2180            ; End this string.
JMP $7FD9

; "Can't equip!" text.
NoEqTxt:
DB $82,$9A,$A7,$C3,$AD,$FF,$9E,$AA,$AE,$A2,$A9,$BE,$00

; Esper equip table.
; Bitmask for which characters can equip the esper
; $0001    = Terra can equip
; $0002    = Locke
; $0004    = Cyan
; $0008    = Shadow
; $0010    = Edgar
; $0020    = Sabin
; $0040    = Celes
; $0080    = Strago
; $0100    = Relm
; $0200    = Setzer
; $0400    = Mog
; $0800    = Gau
; $1000    = Gogo
; $2000    = Umaro

; Logical OR them together to let multiple characters equip
; So $0030 = Figaro bros only
; $0141 = girls only
; $3fff = all 14 chars
; etc.

EsperTable:
DW $0000        ; Ramuh
DW $0000        ; Ifrit
DW $0000        ; Shiva
DW $0000        ; Siren
DW $0000        ; Terrato
DW $0000        ; Shoat
DW $0000        ; Maduin
DW $0000        ; Bismark
DW $0000        ; Stray
DW $0000        ; Palidor
DW $0000        ; Tritoch
DW $0000        ; Odin
DW $0000        ; Raiden
DW $0000        ; Bahamut
DW $0000        ; Alexander
DW $0000        ; Crusader
DW $0000        ; Ragnarok
DW $0000        ; Kirin
DW $0000        ; ZoneSeek
DW $0000        ; Carbunkle
DW $0000        ; Phantom
DW $0000        ; sraphim
DW $0000        ; Golem
DW $0000        ; Unicorn
DW $0000        ; Fenrir
DW $0000        ; Starlet
DW $0000        ; Phoenix

; EOF