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 Post subject: wdc compiler help needed
PostPosted: Tue Oct 08, 2019 9:39 am 
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Joined: Tue Nov 27, 2018 3:28 pm
Posts: 20
Location: Netherlands..
Hi all, after a long time i decided to pull out my w65c265sxb board again.

i started with the 'led blink' from http://www.mikekohn.net/micro/modern_6502.php.
follow directives, used the naken_asm compiler... and yes result, it works.

not a real fan of the "new" code style from naken_asm
so i decided to translate it to wdc compiler style... and here the troubles begin.

i can compile it, but it will not run on the board...
my guess it's some where in the 8/16 bit of the a/x/y
or in the mode where you switch between 8/16 bit part

where do i go wrong... here is the code...
(ps i just want to run it in 8 bit mode, 65c02 mode that is.. but have no clue how to set 8/16 bit modes in the wdc compiler)

Code:
   
        CHIP   65816
   LONGI   OFF
   LONGA   OFF
   org $1000
   
   start:
   ; Disable interrupts to protect from ROM routines running
   ;sei
   ; Set native mode
   ;clc
   ;xce
   ; Set A to 8-bit
   ;sep #$20
   ; Set X/Y to 16-bit
   ;rep #$10
         
main:
         sei
         cld
        
go:         jsr delay
         jsr on
         jsr delay
         jsr off
         jmp go
         
         ; on led
on:         lda #$00
           sta $df23
         rts
           
           ; led off
off:              lda #$ff
           sta $df23
           rts
           
delay:       ldy #$10
delay1:            ldx #$ff
delay2:            dex
           bne delay2
           dey
           bne delay1
           rts


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PostPosted: Tue Oct 08, 2019 10:31 am 
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Location: Berkshire, UK
The XCE instruction is used to control the processor state. So ..
Code:
  sec
  xce

.. will put the device in 65C02 'emulation' mode and the registers will be 8-bits -- no need for SEP/REP.

I wouldn't use port 7 for I/O. Many of the pins are used to generate chip select signals in the default configuration and will ignore the ports data register.

I tend to connect things to port 5 after ensuring DTR/DSR handshaking is disabled on the Uarts or there are some free pins on port 4 but as some are used for interrupts (e.g. 0 and 1) and ROM bank selection (e.g. 3 and 4) you need to set/clr only the free bits (e.g. 2, 5, 6 and 7) using TSB/TRB.

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6502 & PIC Stuff - http://www.obelisk.me.uk/
Cross-Platform 6502/65C02/65816 Macro Assembler - http://www.obelisk.me.uk/dev65/
Open Source Projects - https://github.com/andrew-jacobs


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PostPosted: Tue Oct 08, 2019 6:48 pm 
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Joined: Tue Nov 27, 2018 3:28 pm
Posts: 20
Location: Netherlands..
Thx man.. that's the one..!

all works now..

still hard to figure out what to use at the beginning if you start a program.
setting 8/16 bits, native or emulation.. sep/rep, longi, longa, chip ect ect...
good thing there is nice documentation here at 6502.org ....

all restarts are hard in the beginning...


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PostPosted: Tue Oct 08, 2019 8:39 pm 
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Joined: Fri Aug 30, 2002 1:09 am
Posts: 8546
Location: Southern California
I know you just copied JoeDavisson's routines, but here are just a few pointers anyway:
Quote:
(ps i just want to run it in 8 bit mode, 65c02 mode that is..

Note that running with 8-bit registers is separate from '02 emulation mode. You can still have 8-bit registers in '816 native mode.

SEI (set interrupt disable bit) and CLD (clear decimal-mode bit) are part of the reset sequence and the interrupt sequence; so there's no need to do them in the reset routine unless you might branch to it from a running program. Also, the '816 comes out of reset in '02-emulation mode; so if that's what you want, there's no need to explicitly tell it.

Rather than LDA #0, STA___, you can just use the STZ (store zero) instruction which is faster, takes less memory, and leaves the accumulator and status register alone.

If you know a register or memory location is 0 and you want to make it $FF (or $FFFF if A is 16-bit), you can just do DEC___ instead of LDA #$FF, STA___. If you use a memory location as a flag and want to set it and all that matters is whether it's 0 or not (and you branch on the Z flag), or you only look at the high bit (and then branch on the N flag), you can also just do DEC as long as you can know you're not decrementing so many time that the value again becomes 0 (in the first case) or positive (in the second case).

Your JMP GO could be replaced with BRA GO for a one-byte savings. The execution time is the same.

JSR's to a one-instruction subroutine can be replaced with a macro that just inlines that one instruction (like STZ $DF23) and then the descriptive macro name accomplishes the purpose of being clear about what you're doing, and the JSR/RTS overhead is eliminated.

Almost none of the 6502 primer is specifically about the '816, but you should find its programming tips page helpful anyway, at http://wilsonminesco.com/6502primer/PgmTips.html .

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