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sxb-hacker.asm
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sxb-hacker.asm
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;===============================================================================
; ______ ______ _ _ _
; / ___\ \/ / __ ) | | | | __ _ ___| | _____ _ __
; \___ \\ /| _ \ _____| |_| |/ _` |/ __| |/ / _ \ '__|
; ___) / \| |_) |_____| _ | (_| | (__| < __/ |
; |____/_/\_\____/ |_| |_|\__,_|\___|_|\_\___|_|
;
; A program for Hacking your W65C265SXB or W65C816SXB
;-------------------------------------------------------------------------------
; Copyright (C),2015-2018 Andrew Jacobs
; All rights reserved.
;
; This work is made available under the terms of the Creative Commons
; Attribution-NonCommercial-ShareAlike 4.0 International license. Open the
; following URL to see the details.
;
; http://creativecommons.org/licenses/by-nc-sa/4.0/
;
;===============================================================================
; Notes:
;
; This program provides a simple monitor that you can use to inspect the memory
; in your SXB and reprogram parts of the flash ROM.
;
;-------------------------------------------------------------------------------
.list on
.p816
.ifdef W65C265SXB
.include "w65c265.inc"
.else
.include "w65c816.inc"
.endif
;===============================================================================
;-------------------------------------------------------------------------------
.macro MNEM P,Q,R
.word ((((P-'@')<<5)|(Q-'@'))<<5)|(R-'@')
.endmacro
;===============================================================================
; ASCII Character Codes
;-------------------------------------------------------------------------------
SOH = $01
EOT = $04
ACK = $06
BEL = $07
BS = $08
LF = $0a
CR = $0d
NAK = $15
CAN = $18
ESC = $1b
DEL = $7f
;===============================================================================
;-------------------------------------------------------------------------------
OP_ADC = 0<<1
OP_AND = 1<<1
OP_ASL = 2<<1
OP_BCC = 3<<1
OP_BCS = 4<<1
OP_BEQ = 5<<1
OP_BIT = 6<<1
OP_BMI = 7<<1
OP_BNE = 8<<1
OP_BPL = 9<<1
OP_BRA = 10<<1
OP_BRK = 11<<1
OP_BRL = 12<<1
OP_BVC = 13<<1
OP_BVS = 14<<1
OP_CLC = 15<<1
OP_CLD = 16<<1
OP_CLI = 17<<1
OP_CLV = 18<<1
OP_CMP = 19<<1
OP_COP = 20<<1
OP_CPX = 21<<1
OP_CPY = 22<<1
OP_DEC = 23<<1
OP_DEX = 24<<1
OP_DEY = 25<<1
OP_EOR = 26<<1
OP_INC = 27<<1
OP_INX = 28<<1
OP_INY = 29<<1
OP_JML = 30<<1
OP_JMP = 31<<1
OP_JSL = 32<<1
OP_JSR = 33<<1
OP_LDA = 34<<1
OP_LDX = 35<<1
OP_LDY = 36<<1
OP_LSR = 37<<1
OP_MVN = 38<<1
OP_MVP = 39<<1
OP_NOP = 40<<1
OP_ORA = 41<<1
OP_PEA = 42<<1
OP_PEI = 43<<1
OP_PER = 44<<1
OP_PHA = 45<<1
OP_PHB = 46<<1
OP_PHD = 47<<1
OP_PHK = 48<<1
OP_PHP = 49<<1
OP_PHX = 50<<1
OP_PHY = 51<<1
OP_PLA = 52<<1
OP_PLB = 53<<1
OP_PLD = 54<<1
OP_PLP = 55<<1
OP_PLX = 56<<1
OP_PLY = 57<<1
OP_REP = 58<<1
OP_ROL = 59<<1
OP_ROR = 60<<1
OP_RTI = 61<<1
OP_RTL = 62<<1
OP_RTS = 63<<1
OP_SBC = 64<<1
OP_SEC = 65<<1
OP_SED = 66<<1
OP_SEI = 67<<1
OP_SEP = 68<<1
OP_STA = 69<<1
OP_STP = 70<<1
OP_STX = 71<<1
OP_STY = 72<<1
OP_STZ = 73<<1
OP_TAX = 74<<1
OP_TAY = 75<<1
OP_TCD = 76<<1
OP_TCS = 77<<1
OP_TDC = 78<<1
OP_TRB = 79<<1
OP_TSB = 80<<1
OP_TSC = 81<<1
OP_TSX = 82<<1
OP_TXA = 83<<1
OP_TXS = 84<<1
OP_TXY = 85<<1
OP_TYA = 86<<1
OP_TYX = 87<<1
OP_WAI = 88<<1
OP_WDM = 89<<1
OP_XBA = 90<<1
OP_XCE = 91<<1
MD_ABS = 0<<1 ; a
MD_ACC = 1<<1 ; A
MD_ABX = 2<<1 ; a,x
MD_ABY = 3<<1 ; a,y
MD_ALG = 4<<1 ; al
MD_ALX = 5<<1 ; al,x
MD_AIN = 6<<1 ; (a)
MD_AIX = 7<<1 ; (a,x)
MD_DPG = 8<<1 ; d
MD_STK = 9<<1 ; d,s
MD_DPX = 10<<1 ; d,x
MD_DPY = 11<<1 ; d,x
MD_DIN = 12<<1 ; (d)
MD_DLI = 13<<1 ; [d]
MD_SKY = 14<<1 ; (d,s),y
MD_DIX = 15<<1 ; (d,x)
MD_DIY = 16<<1 ; (d),y
MD_DLY = 17<<1 ; [d],y
MD_IMP = 18<<1 ;
MD_REL = 19<<1 ; r
MD_RLG = 20<<1 ; rl
MD_MOV = 21<<1 ; xyc
MD_IMM = 22<<1 ; # (A or M)
MD_INT = 23<<1 ; # (BRK/COP/WDM)
MD_IMX = 24<<1 ; # (X or Y)
;===============================================================================
; Data Areas
;-------------------------------------------------------------------------------
.segment "ZEROPAGE"
FLAGS: .res 1 ; Emulated processor flags
BUFLEN: .res 1 ; Command buffer length
BANK: .res 1 ; Memory bank
ADDR_S: .res 3 ; Start address
ADDR_E: .res 3 ; End address
BLOCK: .res 1 ; XMODEM block number
RETRIES: .res 1 ; Retry count
SUM: .res 1 ; Checksum
TEMP: .res 4 ; Scratch workspace
.segment "BSS"
BUFFER: .res 128 ; Command buffer
;===============================================================================
; Initialisation
;-------------------------------------------------------------------------------
.segment "CODE"
.export Start
.import UartRx
.import UartTx
.import UartRxTest
.import RomSelect
.import RomCheck
Start:
short_a ; Configure register sizes
long_i
jsr TxCRLF
ldx #TITLE ; Display application title
jsr TxStr
stz BANK ; Reset default bank
;===============================================================================
; Command Processor
;-------------------------------------------------------------------------------
NewCommand:
stz BUFLEN ; Clear the buffer
ShowCommand:
short_i
jsr TxCRLF ; Move to a new line
lda #'.' ; Output the prompt
jsr UartTx
ldx #0
DisplayCmd: cpx BUFLEN ; Any saved characters
beq ReadCommand
lda BUFFER,x ; Yes, display them
jsr UartTx
inx
bra DisplayCmd
RingBell:
lda #BEL ; Make a beep
jsr UartTx
ReadCommand:
jsr UartRx ; Wait for character
cmp #ESC ; Cancel input?
beq NewCommand ; Yes, clear and restart
cmp #CR ; End of command?
beq ProcessCommand ; Yes, start processing
cmp #BS ; Back space?
beq BackSpace
cmp #DEL ; Delete?
beq BackSpace
cmp #' ' ; Printable character
bcc RingBell ; No.
cmp #DEL
bcs RingBell ; No.
sta BUFFER,x ; Save the character
inx
jsr UartTx ; Echo it and repeat
bra ReadCommand
BackSpace:
cpx #0 ; Buffer empty?
beq RingBell ; Yes, beep and continue
dex ; No, remove last character
lda #BS
jsr UartTx
jsr TxSpace
lda #BS
jsr UartTx
bra ReadCommand ; And retry
ProcessCommand:
stx BUFLEN ; Save final length
ldy #0 ; Load index for start
jsr SkipSpaces ; Fetch command character
bcs NewCommand ; None, empty command
;===============================================================================
; B - Select Memory Bank
;-------------------------------------------------------------------------------
cmp #'B' ; Select memory bank?
bne NotMemoryBank
ldx #BANK ; Parse bank
jsr GetByte
bcc *+5
jmp ShowError
jmp NewCommand
NotMemoryBank:
;===============================================================================
; D - Disassemble Memory
;-------------------------------------------------------------------------------
cmp #'D' ; Memory display?
bne NotDisassemble
ldx #ADDR_S ; Parse start address
jsr GetAddr
bcc *+5
jmp ShowError
ldx #ADDR_E ; Parse end address
jsr GetAddr
bcc *+5
jmp ShowError
php
pla
sta FLAGS
Disassemble:
jsr TxCRLF
lda ADDR_S+2 ; Show memory address
jsr TxHex2
lda #':'
jsr UartTx
lda ADDR_S+1
jsr TxHex2
lda ADDR_S+0
jsr TxHex2
jsr TxSpace
jsr TxCodeBytes ; Show code bytes
jsr TxSymbolic ; And instruction
lda [ADDR_S] ; Fetch opcode again
pha
ldy #1
cmp #$18 ; CLC?
bne NotCLC
lda #C_FLAG
bra DoREP
NotCLC:
cmp #$38 ; SEC?
bne NotSEC
lda #C_FLAG
bra DoSEP
NotSEC:
cmp #$c2 ; REP?
bne NotREP
lda [ADDR_S],Y
DoREP: trb FLAGS
bra NextOpcode
NotREP:
cmp #$e2 ; SEP?
bne NextOpcode
lda [ADDR_S],Y
DoSEP: tsb FLAGS
NextOpcode:
pla
jsr OpcodeSize
clc
adc ADDR_S+0 ; And move start address on
sta ADDR_S+0
bcc *+4
inc ADDR_S+1
sec ; Exceeded the end address?
sbc ADDR_E+0
lda ADDR_S+1
sbc ADDR_E+1
bmi Disassemble ; No, show more
jmp NewCommand ; Done
NotDisassemble:
;===============================================================================
; E - Erase ROM bank
;-------------------------------------------------------------------------------
cmp #'E' ; Erase bank?
bne NotEraseBank
jsr CheckSafe
.ifdef W65C265SXB
lda BCR ; Save mask rom state
pha
lda #$80 ; Then ensure disabled
tsb BCR
.endif
lda #$00 ; Set start address
sta ADDR_S+0
lda #$80
sta ADDR_S+1
EraseLoop:
lda #$aa ; Unlock flash
sta $8000+$5555
lda #$55
sta $8000+$2aaa
lda #$80 ; Signal erase
sta $8000+$5555
lda #$aa
sta $8000+$5555
lda #$55
sta $8000+$2aaa
lda #$30 ; Sector erase
sta (ADDR_S)
EraseWait:
lda (ADDR_S) ; Wait for erase to finish
cmp #$FF
bne EraseWait
clc ; Move to next sector
lda ADDR_S+1
adc #$10
sta ADDR_S+1
bcc EraseLoop ; Repeat until end of memory
.ifdef W65C265SXB
pla ; Restore mask ROM state
sta BCR
.endif
jmp NewCommand ; And start over
EraseFailed:
long_i ; Warn that erase failed
ldx #ERASE_FAILED
jsr TxStr
.i8
jmp NewCommand ; And start over
NotEraseBank:
;===============================================================================
; F - WDC Mask ROM Enable/Disable
;-------------------------------------------------------------------------------
.ifdef W65C265SXB
cmp #'F'
bne NotMaskROM
jsr SkipSpaces ; Find first argument
bcs MaskFail ; Success?
cmp #'0' ; Check bank is 0..3
beq MaskOff
cmp #'1'
beq MaskOn
MaskFail:
jmp ShowError
MaskOn:
lda #$80 ; Enable mask ROM
trb BCR
jmp NewCommand
MaskOff:
lda #$80 ; Disable mask ROM
tsb BCR
jmp NewCommand
NotMaskROM:
.endif
;===============================================================================
; G - Goto
;-------------------------------------------------------------------------------
cmp #'G' ; Invoke code
bne NotGoto
ldx #ADDR_S ; Parse execution address
jsr GetAddr
bcs *+5
jmp [ADDR_S] ; Run from address
jmp ($FFFC) ; Otherwise reset
NotGoto:
;===============================================================================
; H - Hunt for RAM
;-------------------------------------------------------------------------------
cmp #'H' ; Hunt for RAM
beq *+5
jmp NotHunt
stz ADDR_S+0 ; Start at $00:0000
stz ADDR_S+1
stz ADDR_S+2
HuntStart:
lda [ADDR_S] ; Is byte is writeable?
pha
eor #$ff
sta [ADDR_S]
cmp [ADDR_S]
beq HuntFound ; Yes
pla
clc ; Try the next block
lda ADDR_S+1
adc #$10
sta ADDR_S+1
bcc HuntStart
inc ADDR_S+2
bne HuntStart
jmp NewCommand ; Reached end of RAM
HuntFound:
jsr TxCRLF
lda ADDR_S+2 ; Print start address
jsr TxHex2
lda #':'
jsr UartTx
lda ADDR_S+1
jsr TxHex2
lda ADDR_S+0
jsr TxHex2
lda #'-'
jsr UartTx
HuntEnd:
pla ; Restore memory bytes
sta [ADDR_S]
clc ; Try the next block
lda ADDR_S+1
adc #$10
sta ADDR_S+1
bcc HuntNext
inc ADDR_S+2
beq HuntDone
HuntNext:
lda [ADDR_S] ; Is byte is writeable?
pha
eor #$ff
sta [ADDR_S]
cmp [ADDR_S]
beq HuntEnd ; Yes, keep looking
pla
sec ; Print end address
lda ADDR_S+0
sbc #1
pha
lda ADDR_S+1
sbc #0
pha
lda ADDR_S+2
sbc #0
jsr TxHex2
lda #':'
jsr UartTx
pla
jsr TxHex2
pla
jsr TxHex2
bra HuntStart
HuntDone:
lda #$ff ; Pring FF:FFFF
pha
pha
jsr TxHex2
lda #':'
jsr UartTx
pla
jsr TxHex2
pla
jsr TxHex2
jmp NewCommand
NotHunt:
;===============================================================================
; M - Display Memory
;-------------------------------------------------------------------------------
cmp #'M' ; Memory display?
bne NotMemoryDisplay
ldx #ADDR_S ; Parse start address
jsr GetAddr
bcc *+5
jmp ShowError
ldx #ADDR_E ; Parse end address
jsr GetAddr
bcc *+5
jmp ShowError
DisplayMemory:
jsr TxCRLF
lda ADDR_S+2 ; Show memory address
jsr TxHex2
lda #':'
jsr UartTx
lda ADDR_S+1
jsr TxHex2
lda ADDR_S+0
jsr TxHex2
ldy #0 ; Show sixteen bytes of data
ByteLoop: jsr TxSpace
lda [ADDR_S],y
jsr TxHex2
iny
cpy #16
bne ByteLoop
jsr TxSpace
lda #'|'
jsr UartTx
ldy #0 ; Show sixteen characters
CharLoop: lda [ADDR_S],Y
jsr IsPrintable
bcs *+4
lda #'.'
jsr UartTx
iny
cpy #16
bne CharLoop
lda #'|'
jsr UartTx
clc ; Bump the display address
tya
adc ADDR_S+0
sta ADDR_S+0
bcc *+4
inc ADDR_S+1
sec ; Exceeded the end address?
sbc ADDR_E+0
lda ADDR_S+1
sbc ADDR_E+1
bmi DisplayMemory ; No, show more
jmp NewCommand
NotMemoryDisplay:
;===============================================================================
; R - Select ROM Bank
;-------------------------------------------------------------------------------
cmp #'R' ; ROM Bank?
bne NotROMBank ; No
jsr SkipSpaces ; Find first argument
bcc *+5 ; Success?
BankFail: jmp ShowError ; No
cmp #'0' ; Check bank is 0..3
bcc BankFail
cmp #'3'+1
bcs BankFail
jsr RomSelect ; Switch ROM banks
jmp NewCommand ; Done
NotROMBank:
;===============================================================================
; S - S19 Record
;-------------------------------------------------------------------------------
cmp #'S' ; S19?
beq *+5
jmp NotS19
jsr NextChar ; Get record type
bcs S19Fail
cmp #'1' ; Only process type 1
bne S19Done
ldx #ADDR_E ; Get byte count
jsr GetByte
bcs S19Fail
lda ADDR_E ; Use as initial checksum
sta SUM
dec ADDR_E
beq S19Fail
ldx #ADDR_S ; Get address
jsr GetAddr
bcs S19Fail
lda ADDR_S+0 ; Add to checksum
adc ADDR_S+1
clc
adc SUM
sta SUM
dec ADDR_E
beq S19Fail
dec ADDR_E
beq S19Fail
S19Load:
ldx #TEMP ; Fetch a data byte
jsr GetByte
bcs S19Fail
lda TEMP
adc SUM
sta SUM
dec ADDR_E
beq S19Fail
lda ADDR_S+2 ; Writing to ROM?
bne WriteS19 ; No
lda ADDR_S+1
bpl WriteS19 ; No
.ifdef W65C265SXB
cmp #$df ; Register page?
beq NoWrite
.endif
lda #$aa ; Yes, unlock flash
sta $8000+$5555
lda #$55
sta $8000+$2aaa
lda #$a0 ; Start byte write
sta $8000+$5555
WriteS19:
lda TEMP ; Write the value
sta [ADDR_S]
NoWrite:
inc ADDR_S+0 ; Bump address by one
bne *+4
inc ADDR_S+1
lda ADDR_E ; Reached checksum?
cmp #1
bne S19Load
ldx #TEMP ; Yes, read it
jsr GetByte
bcs S19Fail
lda TEMP
adc SUM
cmp #$ff ; Checksum correct?
bne S19Fail
S19Done: jmp NewCommand ; Get
S19Fail:
long_i ; Display error message
ldx #INVALID_S19
jsr TxStr
.i8
jmp NewCommand ; And start over
NotS19:
;===============================================================================
; W - Write memory
;-------------------------------------------------------------------------------
cmp #'W' ; Write memory?
bne NotWrite
ldx #ADDR_S ; Parse start address
jsr GetAddr
bcc *+5
jmp ShowError
bit ADDR_S+1 ; Load into ROM area?
bpl *+5
jsr CheckSafe ; Yes, check selection
ldx #ADDR_E ; Parse value byte
jsr GetByte ; Is there a value?
bcc *+5
jmp NewCommand ; No.
lda ADDR_S+2 ; Writing to ROM?
bne WriteMemory ; No
bit ADDR_S+1
bpl WriteMemory ; No
lda #$aa ; Yes, unlock flash
sta $8000+$5555
lda #$55
sta $8000+$2aaa
lda #$a0 ; Start byte write
sta $8000+$5555
WriteMemory:
lda ADDR_E ; Write the value
sta [ADDR_S]
inc ADDR_S+0 ; Bump address by one
bne *+4
inc ADDR_S+1
lda #'W' ; Build command for next byte
jsr StartCommand
lda #' '
jsr BuildCommand
lda ADDR_S+1 ; Add the next address
jsr BuildByte
lda ADDR_S+0
jsr BuildByte
lda #' '
jsr BuildCommand
jmp ShowCommand ; And prompt for data
NotWrite:
;===============================================================================
; X - XMODEM Receive
;-------------------------------------------------------------------------------
cmp #'X' ; XModem upload?
beq *+5 ; Yes.
jmp NotXModem
ldx #ADDR_S ; Parse start address
jsr GetAddr
bcc *+5
jmp ShowError
bit ADDR_S+1 ; Load into ROM area?
bpl *+5
jsr CheckSafe ; Yes, check selection
long_i ; Display waiting message
ldx #WAITING
jsr TxStr
jsr TxCRLF
short_i
stz BLOCK ; Reset the block number
inc BLOCK
ResetRetries:
lda #10 ; Reset the retry counter
sta RETRIES
TransferWait:
stz TEMP+0 ; Clear timeout counter
stz TEMP+1
lda #.lobyte(-20)
sta TEMP+2
TransferPoll:
jsr UartRxTest ; Any data yet?
bcs TransferScan
inc TEMP+0
bne TransferPoll
inc TEMP+1
bne TransferPoll
inc TEMP+2
bne TransferPoll
dec RETRIES
beq TimedOut
jsr SendNAK ; Send a NAK
bra TransferWait
TimedOut:
long_i
ldx #TIMEOUT
jsr TxStr
.i8
jmp NewCommand
TransferScan:
jsr UartRx ; Wait for SOH or EOT
cmp #EOT
beq TransferDone
cmp #SOH
bne TransferWait
jsr UartRx ; Check the block number
cmp BLOCK
bne TransferError
jsr UartRx ; Check inverted block
eor #$ff
cmp BLOCK
bne TransferError
ldy #0
sty SUM ; Clear the check sum
TransferBlock:
jsr UartRx
pha
lda ADDR_S+2 ; Writing to ROM?
bne WriteByte ; No
lda ADDR_S+1
bpl WriteByte ; No
.ifdef W65C265SXB
cmp #$df ; Register page?
beq WriteSkip
.endif
lda #$aa ; Yes, unlock flash
sta $8000+$5555
lda #$55
sta $8000+$2aaa
lda #$a0 ; Start byte write
sta $8000+$5555
WriteByte:
pla
sta [ADDR_S],Y
WriteWait:
cmp [ADDR_S],Y ; Wait for write
bne WriteWait
bra *+3
WriteSkip:
pla
clc ; Add to check sum
adc SUM
sta SUM
iny
cpy #128
bne TransferBlock
jsr UartRx ; Check the check sum
cmp SUM
bne TransferError ; Failed
clc
tya
adc ADDR_S+0 ; Bump address one block
sta ADDR_S+0
bcc *+4
inc ADDR_S+1
jsr SendACK ; Acknowledge block
inc BLOCK ; Bump block number
jmp TransferWait
TransferError:
jsr SendNAK ; Send a NAK
jmp TransferWait ; And try again
TransferDone:
jsr SendACK ; Acknowledge transmission
jmp NewCommand ; Done
SendACK:
lda #ACK
jmp UartTx
SendNAK:
lda #NAK
jmp UartTx
NotXModem:
;===============================================================================
; ? - Help
;-------------------------------------------------------------------------------
cmp #'?' ; Help command?
bne NotHelp
long_i
ldx #HELP ; Output help string
jsr TxStr
.i8
jmp NewCommand
NotHelp:
;-------------------------------------------------------------------------------
ShowError:
long_i
ldx #ERROR ; Output error message
jsr TxStr
.i8
jmp NewCommand
;===============================================================================
;-------------------------------------------------------------------------------
; Checks if an expendable ROM bank is currently selected. If the bank with the
; WDC firmware is selected then warn and accept a new command.
CheckSafe:
jsr RomCheck ; WDC ROM selected?
beq *+3
rts ; No, save to change
pla ; Discard return address
pla
long_i ; Complain about bank
ldx #NOT_SAFE
jsr TxStr
.i8
jmp NewCommand ; And start over
;===============================================================================
; Byte and Word Parsing