About the routine text from right to left(RTL)

[q8fft]

hello, i wondering about the correct way, to flip the routine text dialogues from right to left (LTR to RTL) using ASM.
I have try this before in NES, but not sure about SNES Game because i know nothing really...
is there anyone give tips or guide to this challenge.
hope to find someone interested in this.


thanks...

[madsiur]

It has more to do with FF3us than SNES games meaning the SNES is not limited in this regard. Simply put you need to look at bank $C0. There is a RAM value for position on line ($BF). Instead of starting at #$04 (beginning X position) and checking for ((position += character width) > #$E0 (max X position)) to go to the next line, you start at #$E0 and decrease each time you draw a character, checking for ((#$E0 - position) >= #$04), where position is increased each time you draw (position += current character width).

It's not well documented but by studying the code in bank $C0 it is doable. There would be special stuff like actor names to take care of, check $C08067 for special opcodes cases. I made a text centering opcode and got a good idea of the system. Here is my code to center text:

Code:

;------------------------------------------------------------------------
; Centring Control Character code (OP#$17)
;------------------------------------------------------------------------

CChar:
LDA $BF         ; Load current line position
CMP #$04        ; Beginning of line
BNE brn_exitB   ; Branch if we are not at the start of a line
STZ $3F         ; Current word length: 0
sub_loop:
LDY $00         ; Current dialogue character: pointer + 0
LDA [$C9],Y     ; Load dialogue character
BPL notDTE      ; Branch if not DTE
AND #$7F        ; Isolate DTE ID
ASL A           ; Multiply by 2
TAX             ; Index it
LDA $CF         ; Load text buffer byte
CMP #$80        ; Check if buffer is empty
BEQ .sub_loopB  ; branch if buffer is empty
LDA #$80        ;
STA $CF         ; Set buffer as not empty
BRA secondDTE   ; Verify second DTE character
.sub_loopB
LDA $C0DFA0,X   ; Load DTE character 1          
TAY             ; Transfer A to X
LDA [$1A],Y     ; Load width for variable font cell
CLC             ; Prepare addition (no carry)
ADC $3F         ; Add font cell width to sentence width
STA $3F         ; Save as sentence width
secondDTE:
LDA $C0DFA1,X   ; Load DTE character 2
TAY             ; Save character index
LDA [$1A],Y     ; Load width for variable font cell
CLC             ; Prepare addition (no carry)
ADC $3F         ; Add font cell width to sentence width
STA $3F         ; Save as sentence width
BRA checkEol    ; Check end of line an increment pointer if necessary

notDTE:
LDY $00         ; Clear Index
LDA [$C9],Y     ; Load dialogue character
CMP #$01        ; Is it new line character?
BEQ calcMiddle  ; branch if so (calculate center)
CMP #$11        ; Is it end parameter character?
BEQ calcMiddle  ; branch if so (calculate center)
CMP #$12        ; Is it end parameter character?
BEQ calcMiddle  ; branch if so (calculate center)
CMP #$13        ; Is it end of page character?
BEQ calcMiddle  ; branch if so (calculate center)
CMP #$20        ; Is the character a character code?
BCC incDialog   ; Branch if so (increment dialogue pointer and loop)
TAY             ; Save character index
LDA [$1A],Y     ; Load width for variable font cell
CLC             ; Prepare addition (no carry)
ADC $3F         ; Add font cell width to sentence width
STA $3F         ; Save as sentence width
checkEol:
CMP #$E0        ; Compare to line max width
BCS brn_exitB   ; we have ended the line, there's nothing to center...
incDialog:
INC $C9         ; Increment dialogue
BNE sub_loop
INC $CA
BNE sub_loop
INC $CB
BRA sub_loop
brn_exitB:      
RTS

calcMiddle:
LDA #$E0        ; Load line width
SBC $3F         ; Subtract sentence width
LSR A           ; Divide by 2
STA $BF         ; Store as position in line
TAY
STY $4204       ; Whatever is left, store as to be divided
LDA #$10
STA $4206       ; Divide Y by 16
NOP
NOP
NOP
NOP
NOP
NOP
NOP
LDA $4214      ; Load the division result
STA $4202      ; Store as a multiplier
LDA #$20      
STA $4203      ; Multiply previous result by 32
NOP
NOP
NOP
LDA $4216      ; Get the multiplication result
ADC $C1
STA $C1
BRA brn_exitB

[madsiur]

I wanted to add last night that the main entry point for dialogue display and decoding seems to be $C0814C. There are call to code before and after this offset. Here is also some RAM values from the FF6 wiki that could help:

Code:

$BA-$BC Dialog Window
---------------------
    $BA Enable Dialog Window ($01 = open, $80 = close)
    $BB Dialog Window Size ($00: smallest, $05: fully open)
    $BC Dialog Window Top Y Position ($01: top, $12: bottom)

$BD-$D3 Dialog Text
-------------------
    $BD Current Dialog Character
    $BE Next Dialog Character
    $BF Text's Current X Position on Dialog Window ($04-$E0)
    $C0 Width of Current Word
  + $C1 Pointer to Next Tile in VRAM (+$3800)
  + $C3 Pointer to Current Tile in VRAM (+$3800)
    $C5 Text Graphics Needs to be Copied to VRAM
  + $C6 Unused (set to #$0700)
    $C8 Max X Position on Dialog Window (always $E0?)
++ $C9 Pointer to Current Dialog Character
    $CC current region of dialog window that needs to be cleared in VRAM (starts at 9, decrements once per frame)
        9 = none, waiting for keypress
        +-----------+-----------+
        |     8     |     7     |
        +-----------+-----------+
        |     6     |     5     |
        +-----------+-----------+
        |     4     |     3     |
        +-----------+-----------+
        |     2     |     1     |
        +-----------+-----------+
        0 = none, no text displayed (or map name displayed)
  + $CD Character to Display (top byte is for extra characters from FF6j)
    $CF eppppppp
        e: text buffer is empty
        p: dialog text buffer position (+$7E9183)
  + $D0 Dialog Index
    $D2 -
    $D3 Keypress State (decrements when button is pressed or released)
        0 = not waiting for keypress
        1 = waiting for keypress
        2 = waiting for key release