What assembler to use for GBC assembly hacking?

[Spikeman]

Hey all, I'm hoping to foray into some assembly hacking for the GBC, but I'm not sure what tools to use. My only experience with assembly hacking is for GBA/NDS, where armips is the weapon of choice. I'm looking for an assembler that can assemble code directly into the ROM, similar to how armips handles things. Does such a tool exist? If not, can someone detail how they do this sort of thing?

Thanks.

[LostTemplar]

I have absolutely no experience with GBC hacking nor bass, but I guess you could set up a Z80 architecture for byuu's bass.

[KingMike]

I've used WLA-dx.

To insert stuff, a basic start to the asm code is

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.MEMORYMAP        ;CPU mapping
DEFAULTSLOT 1
SLOT 0 START $0000 SIZE $4000    ;0-3FFF fixed bank
SLOT 1 START $4000 SIZE $4000    ;4000-7FFF swappable bank
.ENDME

.ROMBANKSIZE $4000         ;sets up for a 128KB ROM (8 banks at 16KB each)
.ROMBANKS 8

.BACKGROUND "file.gb"   ;to patch an existing file

.bank 0 slot 0   ;informs the game we are inserting to ROM bank 0,
                       and assume in CPU slot 0 (which we defined above as $0-3FFF)
.org $0A3F    ;CPU address to insert to

To assemble, I use a batch file.

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wla-gb -o source.asm game.o
wlalink -r game.txt game.gb
pause

Where game.txt is like

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[objects]
game.o

[Spikeman]

Thanks guys. It doesn't look like bass supports z80, but WLA-dx is exactly what I'm looking for. (Any reason this isn't in the utilities section?)