mirror of
https://github.com/mgcaret/of816.git
synced 2024-11-15 02:04:52 +00:00
326 lines
9.1 KiB
ArmAsm
326 lines
9.1 KiB
ArmAsm
; Platform support library for WDC W65C816SXB
|
|
;
|
|
; This serves as a "reference" implementation.
|
|
;
|
|
; This file should define any equates that are platform specific, and may be used to
|
|
; define the system interface functions if it is not supplied elsewhere.
|
|
;
|
|
; Generally the system interface is used for console I/O
|
|
; and other such things. The function code is given in the A register, the Y register
|
|
; has the Forth stack depth, and X is the Forth stack pointer vs the direct page.
|
|
; THE X REGISTER MUST REFLECT PROPER FORTH STACK POINTER UPON RETURN!
|
|
;
|
|
; The interface function is called with the Forth direct page and return stack in effect.
|
|
; Function codes $0000-$7FFF are reserved to be defined for use by Forth. Codes $8000-
|
|
; $FFFF may be used by the system implementator for system-specific functions.
|
|
;
|
|
; The system interface must implement functions marked as mandatory.
|
|
; System interface functions shall RTL with the expected stack effects, AY=0, and
|
|
; carry clear if successful; or shall RTL with a code for THROW in AY and carry set on
|
|
; failure. A safe throw code for console I/O is -21 (unsupported operation).
|
|
;
|
|
; Stack cells are 2 words/4 bytes/32 bits, and the stack pointer points to the top of
|
|
; the stack. If the system interface is defined here, the stack manipulation functions
|
|
; defined in interpreter.s may be used. If defined elsewhere, you are on your own for
|
|
; ensuring correct operation on the stack.
|
|
;
|
|
; The system interface functions may use the direct page ZR bytes $00-$03, if they need
|
|
; more than that they can use something reserved elsewhere via long addressing or
|
|
; by temporarily changing the direct page.
|
|
;
|
|
; Here are the function codes, expected stack results, and descriptions
|
|
;
|
|
; $0000 ( -- ) pre initialize platform - called before Forth initialization, to be used
|
|
; for initialization that must take place before Forth initialization.
|
|
; $0001 ( -- ) post initialize platform - called after Forth initialization, to be used
|
|
; for initialization that must take place after Forth initialization.
|
|
; $0002 ( char -- ) emit a character to the console output. This function should
|
|
; implement the control sequences described in IEEE 1275-1994 (a subset of the
|
|
; ANSI terminal standard). For serial devices, this may be assumed.
|
|
; $0003 ( -- f ) f is true if the console input has a character waiting
|
|
; $0004 ( -- char ) read a character from the console (blocking)
|
|
; $0005 ( -- addr ) return pointer to list of FCode modules to evaluate. If pointer is
|
|
; 0, none are evaluated. List should be 32-bit pointers ending in 0.
|
|
; this is never called if FCode support is not included.
|
|
; The system will trust that there is FCode there and not look for a signature.
|
|
; $0006 ( -- ) perform RESET-ALL, restart the system as if reset button was pushed
|
|
|
|
cpu_clk = 8000000
|
|
|
|
.enum ACIA
|
|
RXD
|
|
SR
|
|
CMD
|
|
CTL
|
|
TXD = RXD
|
|
.endenum
|
|
|
|
ACIA1 = $7F80
|
|
|
|
.enum PIA
|
|
PIA
|
|
CRA
|
|
PIB
|
|
CRB
|
|
DDRA = PIA
|
|
DDRB = PIB
|
|
.endenum
|
|
|
|
PIA1 = $7FA0
|
|
|
|
.enum VIA
|
|
ORB
|
|
ORA
|
|
DDRB
|
|
DDRA
|
|
T1C_L
|
|
T1C_H
|
|
T1L_L
|
|
T1L_H
|
|
T2C_L
|
|
T2C_H
|
|
SR
|
|
ACR
|
|
PCR
|
|
IFR
|
|
IER
|
|
ORA2
|
|
IRB = ORB
|
|
IRA = ORA
|
|
.endenum
|
|
|
|
VIA1 = $7FC0
|
|
VIA2 = $7FE0
|
|
|
|
.proc _system_interface
|
|
;wdm 3
|
|
phx
|
|
asl
|
|
tax
|
|
jmp (table,x)
|
|
table: .addr _sf_pre_init
|
|
.addr _sf_post_init
|
|
.addr _sf_emit
|
|
.addr _sf_keyq
|
|
.addr _sf_key
|
|
.addr _sf_fcode
|
|
.addr _sf_reset_all
|
|
.endproc
|
|
.export _system_interface
|
|
|
|
.proc _sf_success
|
|
lda #$0000
|
|
tay
|
|
clc
|
|
rtl
|
|
.endproc
|
|
|
|
.proc _sf_fail
|
|
ldy #.loword(-21)
|
|
lda #.hiword(-21)
|
|
sec
|
|
rtl
|
|
.endproc
|
|
|
|
|
|
.proc _sf_pre_init
|
|
.if 1
|
|
plx
|
|
jmp _sf_success ; assume WDC monitor already did it
|
|
.else
|
|
; set up TIDE interface, the same way WDC does it
|
|
php
|
|
sep #SHORT_A|SHORT_I
|
|
.a8
|
|
.i8
|
|
lda #$00
|
|
sta VIA2+VIA::ACR
|
|
lda #$00
|
|
sta VIA2+VIA::PCR
|
|
lda #%00011000 ; b3 = TUSB_RDB; b4 = ???
|
|
sta VIA2+VIA::ORB
|
|
lda #%00011100 ; set PB2, PB3, PB4 as outputs
|
|
sta VIA2+VIA::DDRB
|
|
lda #$00
|
|
sta VIA2+VIA::DDRA
|
|
lda VIA2+VIA::IRB
|
|
pha
|
|
and #%11101111 ; b4 = ???
|
|
sta VIA2+VIA::ORB
|
|
ldx #$5d
|
|
jsr wait
|
|
pla
|
|
sta VIA2+VIA::ORB
|
|
lda #%00100000 ; b5 = TUSB_PWRENB
|
|
: bit VIA2+VIA::IRB ; wait for USB configuration
|
|
bne :-
|
|
plp
|
|
plx
|
|
jmp _sf_success
|
|
wait: phx ; note 8-bit mode!
|
|
ldx #$00
|
|
: dex
|
|
bne :-
|
|
plx
|
|
dex
|
|
bne wait
|
|
rts
|
|
.a16
|
|
.i16
|
|
.endif
|
|
.endproc
|
|
|
|
.proc _sf_post_init
|
|
plx
|
|
jmp _sf_success
|
|
.endproc
|
|
|
|
.proc _sf_emit
|
|
plx
|
|
jsr _popay
|
|
phx
|
|
php
|
|
sep #SHORT_A|SHORT_I
|
|
.a8
|
|
.i8
|
|
tya
|
|
ldx #$00 ; ensure VIA2 DDR A is set up for input
|
|
stx VIA2+VIA::DDRA
|
|
sta VIA2+VIA::ORA ; set output byte to be sent
|
|
lda #%00000001 ; b0 = TUSB_TXEB
|
|
: bit VIA2+VIA::IRB ; wait for FT245RL to be ready to transmit
|
|
bne :-
|
|
lda VIA2+VIA::IRB
|
|
and #%11111011 ; b2 = TUSB_WR
|
|
tax
|
|
ora #%00000100
|
|
sta VIA2+VIA::ORB ; ensure FT245RL WR high
|
|
lda #$ff ; set up DDR A for output
|
|
sta VIA2+VIA::DDRA ; to present byte to send
|
|
nop ; delay a few cycles
|
|
nop
|
|
stx VIA2+VIA::ORB ; strobe FT245RL WR low
|
|
lda VIA2+VIA::IRA ; ???
|
|
ldx #$00
|
|
stx VIA2+VIA::DDRA ; switch DDR A back to input
|
|
plp
|
|
.a16
|
|
.i16
|
|
plx
|
|
jmp _sf_success
|
|
.endproc
|
|
|
|
.proc _sf_keyq
|
|
lda #$00
|
|
tay ; anticipate false
|
|
php
|
|
sep #SHORT_A
|
|
.a8
|
|
sta VIA2+VIA::DDRA
|
|
lda #%00000010
|
|
bit VIA2+VIA::IRB
|
|
bne :+
|
|
dey ; from $0000 to $FFFF
|
|
: plp
|
|
.a16
|
|
tya
|
|
plx
|
|
jsr _pushay
|
|
jmp _sf_success
|
|
.endproc
|
|
|
|
.proc _sf_key
|
|
php
|
|
tay
|
|
sep #SHORT_A|SHORT_I
|
|
.a8
|
|
.i8
|
|
lda #$00
|
|
sta VIA2+VIA::DDRA ; Ensure VIA2 DDR A is set up for input
|
|
lda #%00000010 ; b1 = TUSB_RXFB
|
|
: bit VIA2+VIA::IRB ; wait for FT245RL to have data & be ready
|
|
bne :-
|
|
lda VIA2+VIA::IRB
|
|
ora #%00001000 ;b3 = TUSB_RDB
|
|
tax
|
|
and #%11110111
|
|
sta VIA2+VIA::ORB ; strobe FT245RL RD# low
|
|
nop ;delay some cycles
|
|
nop
|
|
nop
|
|
nop
|
|
ldy VIA2+VIA::IRA ; receive byte
|
|
stx VIA2+VIA::ORB ; strobe FT245RL RD# high
|
|
plp
|
|
.a16
|
|
.i16
|
|
lda #$0000
|
|
plx
|
|
jsr _pushay
|
|
jmp _sf_success
|
|
.endproc
|
|
|
|
.proc _sf_fcode
|
|
.if include_fcode
|
|
ldy #.loword(list)
|
|
lda #.hiword(list)
|
|
.else
|
|
lda #$0000
|
|
tay
|
|
.endif
|
|
plx
|
|
jsr _pushay
|
|
jmp _sf_success
|
|
.if include_fcode
|
|
list:
|
|
.if romloader_at_init
|
|
.dword romldr
|
|
.endif
|
|
.dword 0
|
|
.if romloader_at_init
|
|
romldr: PLATFORM_INCBIN "fcode/romloader.fc"
|
|
.endif
|
|
.endif
|
|
|
|
.endproc
|
|
|
|
; SXB really can't do this when ROM is banked out. Maybe restart Forth instead?
|
|
.proc _sf_reset_all
|
|
plx
|
|
jmp _sf_fail
|
|
.endproc
|
|
|
|
; Read ROM, virtual address $bb00xxxx in WR, length in XR, destination in YR
|
|
; where bb is the ROM bank number (0-3) and xxxx is the physical address in the ROM.
|
|
; This routine will be moved into RAM in order to read the contents of the ROM.
|
|
.proc _sxb_readrom
|
|
php ; save register size & interrupt state
|
|
sei ; disable IRQs since we are switching the ROM
|
|
sep #SHORT_A
|
|
.a8
|
|
lda VIA2+VIA::PCR ; save existing PCR
|
|
pha
|
|
lda #$00
|
|
xba
|
|
lda WR+3
|
|
and #%00000011
|
|
tay
|
|
lda banktab,y
|
|
sta VIA2+VIA::PCR
|
|
ldy XR
|
|
lp: dey
|
|
bmi done
|
|
lda [WR],y
|
|
sta [YR],y
|
|
bra lp
|
|
done: pla
|
|
sta VIA2+VIA::PCR ; restore PCR
|
|
plp ; restore register size & interrupt state
|
|
.a16
|
|
rtl ; note long return
|
|
banktab: .byte %11001100
|
|
.byte %11000000
|
|
.byte %00001100
|
|
.byte %00000000
|
|
.endproc
|