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[Show Content] [Hide Content]It seems impossible to kill the last boss in this specific set ...
This is in fact NOT a bug because of an extra test that prevents boss energy to be decremented ...
First, let's list the useful adresses to know :
- 0xc301 : level (range 0x00-0x1f)
- 0xc300 : area (range 0x00-0x07) = level / 4 (always rounded down)
- 0xc319 : boss energy (when you reach it - this adresses has another unknown purposes elsewhere)
Then, let's have a look at a "valid" set (eg: 'wboy) :
2FED: 3A 04 93 ld a,($C300)
2FF0: 4F ld c,a
2FF1: 87 add a,a
2FF2: 81 add a,c
2FF3: C6 58 add a,$08
2FF5: DD 77 5D ld (ix+$19),a
This initializes boss energy with a simple formula : energy = area * 3 + 8 ...
And here is the main routine :
Part 1:
3006: 11 0B 42 ld de,$120E
3009: CD E9 64 call $20B9 routine that tests if boss is hit
300C: 30 57 jr nc,$3021 if boss isn't hit, jump to Part 2
300E: DD 35 59 dec (ix+$19) energy = energy - 1
3011: 28 71 jr z,$3044 if energy = 0, jump to Part 3 (boss is dead)
3013: DD 36 1F 1D ld (ix+$1a),$08 Initialize the values to make the head "flash"
3017: 0E 16 ld c,$46
3019: CD 7A 69 call $2D2A
301C: 3E 47 ld a,$03
301E: CD 1C 0F call $0E58
Part 2:
3021: 11 0F 17 ld de,$120E
3024: CD 6F 35 call $206A
3027: 30 55 jr nc,$302E
3029: 21 0E 8C ld hl,$C85E
302C: CB D6 set 2,(hl)
302E: CD B5 75 call $30F1
3031: DD 7E 1F ld a,(ix+$1a)
3034: B7 or a
3035: 28 1F jr z,$3041
3037: DD 35 5E dec (ix+$1a)
303A: 20 41 jr nz,$3041
303C: 0E 69 ld c,$2D
303E: CD 6E 29 call $2D2A
3041: C3 F5 60 jp $30F1
Part 3:
3044: 0E 7D ld c,$2D
Now look at what we have in 'wboyu' ...
Even if the adresses are different, the initialization routine is the same :
2DA0: 3A 00 C3 ld a,($C300)
2DA3: 4F ld c,a
2DA4: 87 add a,a
2DA5: 81 add a,c
2DA6: C6 08 add a,$08
2DA8: DD 77 19 ld (ix+$19),a
But the main routine is slightly different :
Part 1:
2DB9: 11 0E 12 ld de,$120E
2DBC: CD 05 1F call $1F05 routine that tests if boss is hit
2DBF: 30 1A jr nc,$2DDB if boss isn't hit, jump to Part 2
2DC1: 3A 00 C3 ld a,($C300)
2DC4: FE 06 cp $06 have we reached area 7 ?
2DC6: 30 05 jr nc,$2DCD if this is the case, jump to Part 1b
2DC8: DD 35 19 dec (ix+$19) energy = energy - 1
2DCB: 28 31 jr z,$2DFE if energy = 0, jump to Part 3 (boss is dead)
Part 1b:
2DCD: DD 36 1A 08 ld (ix+$1a),$08 Initialize the values to make the head "flash"
2DD1: 0E 46 ld c,$46
2DD3: CD 24 2B call $2B24
2DD6: 3E 03 ld a,$03
2DD8: CD 4A 0D call $0D4A
Part 2:
2DDB: 11 0E 12 ld de,$120E
2DDE: CD B6 1E call $1EB6
2DE1: 30 05 jr nc,$2DE8
2DE3: 21 5E C8 ld hl,$C85E
2DE6: CB D6 set 2,(hl)
2DE8: CD 8C 2E call $2E8C
2DEB: DD 7E 1A ld a,(ix+$1a)
2DEE: B7 or a
2DEF: 28 0A jr z,$2DFB
2DF1: DD 35 1A dec (ix+$1a)
2DF4: 20 05 jr nz,$2DFB
2DF6: 0E 2D ld c,$2D
2DF8: CD 24 2B call $2B24
2DFB: C3 8C 2E jp $2E8C
Part 3:
2DFE: 0E 2D ld c,$2D
As you can see, boss energy is NEVER decremented when you reach area 7 or 8, so the level can NEVER end !
On a side note, there is an interesting routine in all "valid" sets which is called before initializing boss energy :
Part 1:
2C8F: 3A 50 87 ld a,($C300)
2C92: D6 42 sub $06
2C94: 38 5E jr c,$2CB0
2C96: 3D dec a
2C97: 28 03 jr z,$2CA0
2C99: 3A 10 93 ld a,($C314)
2C9C: FE 4C cp $1C
2C9E: 30 40 jr nc,$2CB0
Part 2:
2CA0: 3E 45 ld a,$01
2CA2: 32 57 93 ld ($C313),a
2CA5: 3E F8 ld a,$A8
2CA7: 32 9C 99 ld ($C998),a
2CAA: 21 30 3B ld hl,$3F60
2CAD: 22 94 99 ld ($C990),hl
Part 3:
2CB0: 21 3D 94 ld hl,$C479
2CB3: 34 inc (hl)
2CB4: C9 ret
This routine tests the area and the number of dolls you collected : if you don't have (at least) 28 dolls
after completing area 7 round 4 (which means you haven't taken ALL of them since the begining),
the game will end and you won't be able to play the 4 rounds from area 8 !
This routine doesn't even exist in 'wboyu' because, as we saw above, you can never kill 7th boss !
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wboyu_notbug.txt (4,783 bytes) Jan 9, 2010, 11:49 
