Gameboy Camera - Force Trippy H (Page 3 of 3)

Sorry guys! Super busy. Here is what I have on my work PC

Known Routines:

$097D - "Delay_1" This is a delay routine, value passed via BC
$03AD - "LCD_Turn_Off" No variables passed
$0462 - "Zero_RAM"    Start location passed in HL, number of bytes to zero in BC
$03E2 - "DMA_Routine_2_HRAM" , No Variables, moves a 10 byte program into HRAM, the DMA routine.
$092A - "Init_OAM_Buffer"    ;Sets the OAM buffer ($D400) to 0xF0
$0914 - "Clear_Tile_Map0"    ;sets $9800-9BFF to $FF
$091F - "Clear_Tile_Map1"     ;sets $9C00-9FFF to $FF
$2B25 - "Init_Snd"        ;Turns sound registers on, volume, channels, clears DD00-DF00
$1DEC -
$1DE0 - "Delay_2" , No variables Passed.

Known Memory Locations:
$FF9B - Current Memory Bank selected
$D400 - D49F - DMA Start address (Buffer?)
$DD00-DF00 - Suspected Sound buffers?

$0101: Jp Main

Main:
    Ld sp, $FFFE         ;Initialise Stack
    Di            ;disable interrupts
    Xor a            ;clear a
    Ldh [$FF0F], a    ;Dissable all IRQ’s
    Ldh a,[$FF40]        ;Get LCDC
    Bit 7,a            ;Test bit 7 – Display Enabled?
    Jr zn, LCD_Enabled    ;Conditional Jump ()
    Set 7,a            ;set bit 7
    Ldh [$FF40],a        ;Store LCDC

LCD_Enabled:
    Ld bc, $0002        ;pass $0002 to Function $097D
    Call Delay_1         ;Jazz, Please watch this in the emulator to find the delay length?
                ;Best guess is the delay is necessary to initialise the cart MCU

VblankWait:
    Ldh a,[FF44]        ;Waiting for a V-Blank…
    Cp a,$91
    Jr c,VblankWait

    Ld a,$80
    Ldh [$FF40],a ;Enable LCD – Did I make a mistake with the above routines? Jazz?
    Xor a         ;Clear A
    Ldh [$FF47],a     ;Clear Pallete Data
    Ldh [$FF48],a     ;Clear Pallete Data
    Ldh [$FF49],a     ;Clear Pallete Data

    Ld bc, $0002        ;pass $0002 to Function $097D
    Call Delay_1         ;Jazz, Please watch this in the emulator to find the delay length?
       
    Call  Turn_LCD_Off   

    ld hl,$C000        ;Load HL with Work RAM location
    ld BC,$1FFF        ;Load BC with 1FFF
    Call Zero_RAM        ;Zero BC number of bytes, from location HL

    ld   a,$00        ;Why do they zero A this way, and not XOR A like other routines???
    ld   [$0000],a        ;Disable Cartridge Save RAM
    ld   a,$01        ;
    ld   [$2000],a        ;Set ROM bank 1
    ld   a,$00       
    ld   [$4000],a        ;Set Ram bank 0
    ld   a,$01
    ldh  [$FF9B],a        ;Store 1 into FF9B - Perhaps a buffer to keep track of bank numbers?
    ld   sp,$DFFF        ;Move stack pointer to $DFFF
    ld   hl,$FF80        ;Load $FF80 into HL
    ld   bc,$007E        ;Load $007E into BC
    Call Zero_RAM        ;Clear the HRAM

   
    Call DMA_Routine_2_HRAM ;move the DMA routine to HRAM

    Call Init_OAM_Buffer    ;Sets the OAM buffer ($D400) to 0xF0

    Call Clear_Tile_Map0

    Call Clear_Tile_Map1

    xor a    ;Clear A
   
    ld   [$D520],a    ;Zero all these important registers...
    ld   [$D521],a
    ld   [$D522],a
    ldh  [$FFC5],a
    ldh  [$FFC6],a
    ldh  [$FFD0],a
    ldh  [$FFD4],a
    ld   [$DC41],a
    ld   [$D523],a
    ldh  [$FFC4],a

    ld   hl,$FFAB
    xor  a
    ldi  [hl],a    ;Zero from  FFAB - FFB2
    ldi  [hl],a
    ldi  [hl],a
    ldi  [hl],a
    ldi  [hl],a
    ldi  [hl],a
    ldi  [hl],a
    ldi  [hl],a
    ld   a,$8F
    ldi  [hl],a    ;$8F into FFB3
    ld   a,$A6
    ldi  [hl],    ;$A6 into FFB4

    Call Init_Snd    ;

    Call $1DEC    ;

$1DEC:
    ld   a,$0B
    ld   hl,$4010
    call $1D95

    call Delay_2

    ldh  a,[$FF00]
    and  a,$03
    cp   a,$03
    jr   nz,$1E3A
    ld   a,$20
    ldh  [$FF00],a
    ldh  a,[$FF00]
    ldh  a,[$FF00]
    ld   a,$30
    ldh  [$FF00],a
    ld   a,$10
    ldh  [$FF00],a
    ldh  a,[$FF00]
    ldh  a,[$FF00]
    ldh  a,[$FF00]
    ldh  a,[$FF00]
    ldh  a,[$FF00]
    ldh  a,[$FF00]
    ld   a,$30
    ldh  [$FF00],a
    ldh  a,[$FF00]
    ldh  a,[$FF00]
    ldh  a,[$FF00]
    ldh  a,[$FF00]
    and  a,$03
    cp   a,$03
    jr   nz,$1E3A
    ld   a,$0B
    ld   hl,$4000
    call $1D95
    call $1DE0
    and  a
    ret 
    ld   a,$0B
    ld   hl,$4000
    call $1D95
    call Delay_2
    scf 
    ret 

$1D95:    ;Variables passed, A and HL

    ldh  [$FF9D],a        ;put variable A into FF9D - Temp bank buffer 2?
    ldh  a,[BankBuffer]    ;Get current bank
    push af            ;Store it on the stack
    ldh  a,[$FF9D]        ;Get that variable buffer
    ldh  [BankBuffer],a    ;Update the current bank register
    ld   [$2000],a        ;Set the bank
    ld   a,[hl]        ;Load first byte of passed variable HL
    and  a,$07        ;cmp with $07
    jr   z,Label1        ;if something, then end routine.....

    ld   b,a        ;otherwise,  multiply it by 0xFF, and put it in BC
    ld   c,$00
    push bc            ;push BC onto the stack
    ld   a,$00       
    ld   [$ff00+c],a    ;Clear keypad latch
    ld   a,$30
    ld   [$ff00+c],a    ;Set P14+15 high
    ld   b,$10        ;load B with $10
Label4:    ld   e,$08        ;Load E with $08
    ldi  a,[hl]       
    ld   d,a
Label3:    bit  0,d
    ld   a,$10
    jr   nz,Label2
    ld   a,$20
Label2:    ld   [$ff00+c],a
    ld   a,$30
    ld   [$ff00+c],a
    rr   d
    dec  e
    jr   nz,Label3
    dec  b
    jr   nz,Label4
    ld   a,$20
    ld   [$ff00+c],a
    ld   a,$30
    ld   [$ff00+c],a
    pop  bc
    dec  b
    jr   z,Label1
    call Delay_2
    jr   $1DA9
Label1:    pop  af
    ldh  [BankBuffer],a
    ld   [$2000],a
    ret 

Delay_2:
    ld   de,$1B58
.Loop    nop 
    nop 
    nop 
    dec  de
    ld   a,d
    or   e
    jr   nz,.Loop
    ret 

Init_Snd: ;Set bank 1F, execute code at $7FF6, Restore previous bank.
    ldh  a,[$FF9B] ;Store the current ROM bank
    push af
    ld   a,$1F    ;Change to ROM Bank 1F
    ldh  [$FF9B],a    ;Update the bank buffer
    ld   [$2000],a    ;Switch bank 1F
    call $7FF6    ;Turn on Sound registers, Zero DD00-DF00 - Sound buffers???
    pop  af        ;Restore the current rom bank
    ldh  [$FF9B],a    ;
    d   [$2000],a    ;Set the current rom bank.
    ret     

        1F:7FF6 > jumps to :5343
        1F:5343:
            ld   a,$80
            ldh  [$FF26],a    ;Enable all sound channels
            ld   a,$77
            ldh  [$FF24],a  ;Max volume
            ld   a,$FF
            ldh  [$FF25],a    ;Sound output to all terminals
            ld   hl,$DD00
        .Loop    ld   [hl],$00    ;Zero DD00-DF00
            inc  l
            jr   nz,.Loop
            inc  h
            ld   a,h
            cp   a,$DF
            jr   nz,.Loop
            ret 

Clear_Tile_Map0:
    ld   a,$FF
    ld   hl,$9800
    ldi  [hl],a
    bit  2,h
    jr   z,$0919
    ret 

Clear_Tile_Map1:
    ld   a,$FF
    ld   hl,$9C00
    ldi  [hl],a
    bit  5,h
    jr   z,$0924
    ret 
   

Init_OAM_Buffer: ;Set OAM buffer to 0xF0, all of it.
    ld   hl,$D400
    ld   b,$A0
    ld   a,$F0
    ldi  [hl],a
    dec  b
    jr   nz,$0931
    xor  a
    ldh  [$FF9A],a
    ret 

DMA_Routine_2_HRAM: ;Move the DMA transfer routine into HRAM
    ld   c,$80
    ld   b,$0A
    ld   hl,DMA_Routine   
    ldi  a,[hl]    ;
    ld   [$ff00+c],a
    inc  c
    dec  b
    jr   nz,$03E9
    ret     

DMA_Routine:    ;This routine is placed into HRAM via DMA_Routine_2_HRAM
    ld a,$D4        ;Start address = $D400, Destination is FE00
    ldh [$FF46],a
    ld a,$28
    dec a
    jr nz,$03F6
    Ret

Zero_RAM:
    xor  a
    ldi  [hl],a
    dec  bc
    ld   a,c
    or   b
    jr   nz,$0462
    ret    

Turn_LCD_Off:
    Ldh a,[$FF40]     ; get LCDC
    Bit 7,a        ;Disabled?
    Ret z        ;return with zero flag carried
    Ldh a,[$FFFF]    ;Get Interrupt Status
    Push AF        ;push it to the stack
    And A,$FC    ;Clear bits 0+1 – Vblank int, and LCD Stat int.
    Ldh [$FFFF],A    ;Update the interrupt status

.Wait4V:
    Ld a,[FF44]
    Cp a,$91
Jr nz, .Wait4V
   
    Ldh a,[$FFAB]    ;FFAB is a buffer register of LCDC
    Res 7,a
    ldh [$FF40],a    ;store in LCDC
    ldh [$FFAB],a   ;Update LCDC buffer register   
    pop af
    ldh [$FFFF],a    ;restore the Interupt register
    RET

Delay_1 : ;Data passed in via Register BC
    Ld de,$06D6        ;Delay loop pre-set
Delay_Inner_Loop:
    Nop
    Nop
    Nop
    Dec de            ;
    Ld a,d            ;
    Or e            ;
    Jr nz, Delay_Inner_Loop: ;Loop $06D6 times
    Dec BC
    Ld a,b
    Or c
    Jr nz, Delay_1: ;Loop the above loop, BC times.
    Ret

There is more on my home PC