author: madsiur
version: 1.1
released on: 2016/04/28
Apply to a FF3us 1.0 ROM
Download
Files
randomsongsC2.asm: For implementation in bank $C2
randomsongsEE.asm: For implementation in bank $EE or any other bank
Apply with xkas 0.06
Command example: xkas randomsongsEE.asm romname.smc
Description
Randomize the battle theme and default boss song. By default the max number of song for the battle theme is 8 and 4 for the boss theme.
By default, battleTable and bossTable have their entries nullified with only the default song as entry. Replace the !noSong in a table to add a song choice. You can also reduce or expand the tables. If your table has 50% or more of null values (!nosong) it is more efficient to reduce it in half (e.g. remove 4 lines for a 8 song table) than nullifying most of the entries. You'll also need to change the !numSongBattle and/or !numSongBoss value(s).
What the code does is if he picks a null value it will choose a new random number and repick from the table. If tables are modified properly, the repick probability will always be less than 50%, e.g. 44% maximum for a 16 songs table. The probability of a total of 3 picks before getting a song is 19% maximum and for 4 picks or more is 8,5%. So basically there can be relooping and cycles wasted but I don't consider it significant taking in account it was the easiest solution code-wise.
To recap, if you want 12 possible songs for the battle theme, add 8 lines to the table and nullifie 4 entries (!noSong). Then you need to change the !numSongBattle variable to $0F.
Extra notes: This is a hack that uses the default RNG table at $C0FD00,X, meaning for now it is a much random as the default RNG system can be. Also, having table that are 2^X entries is not the optimal system since cycles are wasted for repicking in case of null entries. I'm opened to suggestion to improve both aspect, especially having as an example a table of 10 entries for 10 songs, not a table of 16 entries with 6 null values in it.
Assembly file:
version: 1.1
released on: 2016/04/28
Apply to a FF3us 1.0 ROM
Download
Files
randomsongsC2.asm: For implementation in bank $C2
randomsongsEE.asm: For implementation in bank $EE or any other bank
Apply with xkas 0.06
Command example: xkas randomsongsEE.asm romname.smc
Description
Randomize the battle theme and default boss song. By default the max number of song for the battle theme is 8 and 4 for the boss theme.
By default, battleTable and bossTable have their entries nullified with only the default song as entry. Replace the !noSong in a table to add a song choice. You can also reduce or expand the tables. If your table has 50% or more of null values (!nosong) it is more efficient to reduce it in half (e.g. remove 4 lines for a 8 song table) than nullifying most of the entries. You'll also need to change the !numSongBattle and/or !numSongBoss value(s).
What the code does is if he picks a null value it will choose a new random number and repick from the table. If tables are modified properly, the repick probability will always be less than 50%, e.g. 44% maximum for a 16 songs table. The probability of a total of 3 picks before getting a song is 19% maximum and for 4 picks or more is 8,5%. So basically there can be relooping and cycles wasted but I don't consider it significant taking in account it was the easiest solution code-wise.
To recap, if you want 12 possible songs for the battle theme, add 8 lines to the table and nullifie 4 entries (!noSong). Then you need to change the !numSongBattle variable to $0F.
Extra notes: This is a hack that uses the default RNG table at $C0FD00,X, meaning for now it is a much random as the default RNG system can be. Also, having table that are 2^X entries is not the optimal system since cycles are wasted for repicking in case of null entries. I'm opened to suggestion to improve both aspect, especially having as an example a table of 10 entries for 10 songs, not a table of 16 entries with 6 null values in it.
Assembly file:
Code:
hirom ; Don't change this.
header ; Comment out if your ROM has no header.
; Configuration
!battleSongId = $24 ; Change only if you changed its value in the $C2BF3B table.
!bossSongId = $14 ; Change only if you changed its value in the $C2BF3B table.
!noSong = $FE ; "null" song ID value.
!numSongBattle = $07 ; X - 1 battle songs, where X = 2^Y and Y <= 7.
!numSongBoss = $03 ; X - 1 boss songs, where X = 2^Y and Y <= 7.
; In other words, these last two variable must equal
; $01, $03, $07, $0F, $1F, $3F or $7F for respectively
; 2, 4, 8, 16, 32, 64 or 128 songs.
; Code
org $C2BDB7
JSL randomness
BRA continue
; Code from above BRA up to here is skipped, since it is no longer needed
org $C2BDCD
continue:
; This can go anywhere where there is enough free space
org $EEAF01
randomness:
LDA $C2BF3B,X ; Load song ID
CMP #$FF
BEQ return ; Branch if we keep the current music playing
CMP #!battleSongId ; Check if battle song
BEQ getBattle
CMP #!bossSongId ; Check if boss song
BEQ getBoss
BRA loadSong ; otherwise just load the song
getBattle:
JSR getRandom ; Get random number
AND #!numSongBattle ; Reduce it to a number from 0 to 7
TAX
LDA battleTable,X ; Load the table song
CMP #!noSong ; Check if "null" value
BEQ getBattle ; Get another random number if "null"
BRA loadSong ; Otherwise load song
getBoss:
JSR getRandom ; Get random number
AND #!numSongBoss ; Reduce it to a number from 0 to 3
TAX
LDA bossTable,X ; Load the table song
CMP #!noSong ; Check if "null" value
BEQ getBoss ; Get another random number if "null"
loadSong:
STA $1301 ; Save song ID
LDA $11E4
AND #$08
BNE return
JSL $C50004 ; Play song
return:
RTL
getRandom:
LDA $1F6D ; Get RNG index
INC $1F6D ; Increment RNG index
TAX
LDA $C0FD00,X ; Get random number
RTS
; It is more efficient to reduce a table to its half than
; nullifying 50% or more of its entries.
battleTable:
db $24
db !noSong
db !noSong
db !noSong
db !noSong
db !noSong
db !noSong
db !noSong
bossTable:
db $14
db !noSong
db !noSong
db !noSong
Moogles FTW