arch nes.cpu

output "decode.bin", create
fill 65536
origin 0

macro align(size) { // Align Byte Amount
    while (pc() % {size}) {
        db 0
    }
}

macro nops(new_pc) {
    if (pc() > {new_pc}) {
        error "PC is already past the point specified"
    }
    while (pc() < {new_pc}) {
        print "adding a byte of padding at "
        print pc()
        print "\n"
        nop
    }
}

define version(6)

fill 8, $02 // jams

start:
cld // clear BCD flag
clc // clear carry
clv // clear overflow
// TODO: what i actually should be doing is an RTI
pla
pla
tax
tay
nop //php // push processor status just to advance stack a bit

macro when_to_stop() {
    if 1 {
        lda $02
        cmp #(name1 & 0xFF)
        beq decode_begin_next
        cmp #(name2 & 0xFF)
        beq decode_begin_next
        cmp #(name3 & 0xFF)
        beq decode_begin_next
        cmp #(name4 & 0xFF)
        beq decode_begin_next
        cmp #(name5 & 0xFF)
        beq decode_exit
    } else {
        // FIXME: doesn't work because output has already advanced to a null byte.
        ldy #0
        lda #$20 // ascii space
        eor ($00),y // load from output
        beq decode_begin_next
        lda $02
        cmp #(name5 & 0xFF)
        beq decode_exit
    }
}

// decode subroutine arguments:
lda #(names_out)
sta $00
lda #(names_out >> 8)
sta $01
lda #(names)
sta $02
lda #(names >> 8)
sta $03
jsr decode
db $D2 // jam (D for Done, i guess)

align(16)
// reorder() { python3 -c 's=__import__("sys").argv[1];print("".join(s[int(bin(len(s)|i)[-1:2:-1],2)] for i in range(len(s))))' "$@"; }
decode_lut0xxx:
db "ETAOINSH"
//db "EIASTNOH"
decode_lut10xx:
db "RDLU"
//db "RDLU"
if {version} >= 3 && {version} <= 6 {
    db "????"
}
decode_lut11xxxx:
db "CMFPGWYBVKXJQZ. "
//db "CVGQFXY.MKWZPJB "

//origin 0x100 - 6 * 5 * 2
align(16)
names_out:
fill 6 * 5 * 2

db $FF

origin 0x200
names:
name0:
// FIXME: names are truncated unless they end in a padding byte!
db $0A,$4F,$4B,$70,$17,$FF // Elizabeth
name1:
db $C4,$A3,$6F,$FF,$FF,$FF // Mary          110001 00.10 1000 11.0110
name2:
db $CC,$86,$13,$04,$2F,$FF // Patricia
name3:
db $EC,$B1,$06,$FF,$FF,$FF // James         111011 00.10 110001. 0000 0110.
name4:
db $83,$DC,$20,$7F,$FF,$FF // Robert
name5:

origin 0x300
if {version} == 1 { ;       include "decode_v1.asm"
} else if {version} == 2 { ;include "decode_v2.asm"
} else if {version} == 3 { ;include "decode_v3.asm"
} else if {version} == 4 { ;include "decode_v4.asm"
} else if {version} == 5 { ;include "decode_v5.asm"
} else if {version} == 6 { ;include "decode_v6.asm"
}

align(16)
db "DONE: "
dw done

origin 0xFFFC
db start
db start >> 8

//macro revbit(variable x) {
//    evaluate lo(((x&(1<<7))>>7)|((x&(1<<6))>>5)|((x&(1<<5))>>3)|((x&(1<<4))>>1))
//    evaluate hi(((x&(1<<3))<<1)|((x&(1<<2))<<3)|((x&(1<<1))<<5)|((x&(1<<0))<<7))
//    db {lo}|{hi}
//}
//macro makename(variable a, variable b, variable c, variable d, variable e) {
//    revbit(a)
//    revbit(b)
//    revbit(c)
//    revbit(d)
//    revbit(e)
//}
//makename($01,$23,$45,$67,$89)

// vim:ft=snes_bass