#!/usr/local/bin/zasm -o ../original/ #target rom ; Z80-EMUF ; -------- ; ; Ein einfaches, benutzbares, emuliertes Z80-System, bestehend aus: ; very simple serial emulation: ; only data register, no control register ; read: 0xFF no data ; 0x20-0xFE ascii character ; write: 0x20-0xFE ascii character sio_data equ $fe epromsize equ $2000 ; eprom size = 8 kB ramstart equ $4000 ; datasize equ $100 ; monitor variables ; ------------------------------------------------------------ ; data segment declaration ; ------------------------------------------------------------ #data Systemvariablen,ramstart,datasize tickercell ds 2 ; interrupt counter ram_top ds 2 ; end of physical ram last_cmd ds 2 ; what the monitor calls, if 'enter' is pressed last_addr ds 2 ; last address used appl_sp ds 2 ; stackpointer of z80 test application break_byte ds 1 ; byte below breakpoint patch break_addr ds 2 ; address of breakpoint patch ; ------------------------------------------------------------ ; code segment ; ------------------------------------------------------------ #code Eprom,0,epromsize ; ------------------------------------------------------------ ; reset entry ; ------------------------------------------------------------ reset: di im 1 jp reset1 defs 8-$ ; ------------------------------------------------------------ ; print character a to sio ; in: a = character to print ; out: -- ; mod: -- ; ------------------------------------------------------------ printchar: out (sio_data),a ret defs 16-$ ; ------------------------------------------------------------ ; read character a from sio ; blocking ; in: -- ; out: a = read character ; mod: flags ; ------------------------------------------------------------ readchar: in a,(sio_data) inc a jr z,readchar dec a ret defs 24-$ ; ------------------------------------------------------------ ; print 0-terminated message ; in: hl -> message ; out: hl -> behind message ; mod: a, hl, flags ; ------------------------------------------------------------ printstr: ld a,(hl) inc hl and a ret z rst printchar jr printstr defs 32-$ ; ------------------------------------------------------------ ; print 0-terminated message ; in: message follows immediately on call ; out: -- ; mod: a, hl, flags ; ------------------------------------------------------------ printmsg pop hl rst printstr jp (hl) defs 40-$ ; ------------------------------------------------------------ ; break point -> switch context: appl -> moni ; ------------------------------------------------------------ breakpoint jp break_point defs 48-$ ; ------------------------------------------------------------ ; unused restart vector ; ------------------------------------------------------------ rst_48 defs 56-$ ; ------------------------------------------------------------ ; the interrupt routine ; ------------------------------------------------------------ interrupt: push af ld a,(tickercell) inc a ld (tickercell),a jr nz,irpt_1 ld a,(tickercell+1) inc a ld (tickercell+1),a irpt_1 pop af ei ret defs $66-$ ; ------------------------------------------------------------ ; the non-maskable interrupt routine ; => immediately enter monitor ; => this may interrupt the interrupt routine. rare case, on the ; emulated system eventuelly impossible (depends on programming) ; check the register listing to determine this state and ; finish the interrupt routine by single stepping if you like ; ------------------------------------------------------------ ; note there should be a test to prevent the nmi from breaking ; into the monitor itself nmi: call retn jp break_point retn retn ; ------------------------------------------------------------ ; include the re-usable utilites ; ------------------------------------------------------------ #include "UTILS.s" ; ------------------------------------------------------------ ; input number ; in: -- ; out: hl = number ; z = ok; ; nz = error ; a = last char (esc/enter/space/comma...) ; ------------------------------------------------------------ esc equ 27 del equ 8 rub equ 127 enter equ 13 tab equ 9 getnumber: ld hl,0 ld c,10 ; default number base ld b,0 ; character counter gn1 rst readchar cp a,del jr z,gn8 cp a,rub jr z,gn8 cp a,27 jr z,gn_err ; abort cp a,'$' jr z,gnx cp a,',' jr z,gn_ret cp a,' ' jr z,gn_ret cp a,tab jr z,gn_ret cp a,enter jr z,gn_ret ; digit cp a,'0' jr c,gn1 cp a,'9'+1 jr c,gn2 ; dec char bit 4,c jr z,gn1 ; dec base but no dec char or a,$20 ; force lower case cp a,'a' jr c,gn1 cp a,'f'+1 jr nc,gn1 rst printchar sub a,'a'-10 jr gn3 gn2 rst printchar sub a,'0' gn3 inc b push af push bc ld e,c ld d,0 call mult pop bc pop af ld e,a ld d,0 add hl,de jr gn1 ; select hex gnx ld a,b and a jr nz,gn1 ld c,16 ; new number base ld a,'$' rst printchar inc b jr gn1 ; delete / rubout gn8 djnz gn81 jr gn_err ; delete & field empty -> abort gn81 rst printmsg defm $08200800 ; rubout gn82 djnz gn81 jr getnumber ; return/space/comma/tab gn_ret dec b jp m,gn_err ; no digit gn_ok cp a,a ; z -> ok ret gn_err and a ; nz -> error ret nz dec a ; ((security only)) ret ; ------------------------------------------------------------ ; reset sequence (ctd.) ; ------------------------------------------------------------ reset1: ld sp,ramstart+datasize call printnl ; welcome message rst printmsg defb 27,'b' defm $0d0a,"z80 EMUF - z80 single board system" defm $0d0a,"----------------------------------",$00 ; ram test rst printmsg defm $0d0a defm $0d0a,"testing ram ",$00 call ramtest ; hl contains ram end ld (ram_top),hl push hl rst printmsg defm $0a0d,"physical ram size: $",$00 pop hl ld bc,ramstart and a sbc hl,bc call printhex4 ; init init init ... ld hl,0 ld (tickercell),hl ei ; more messages ... rst printmsg defb $0a defm $0d0a,"this is an emulation of a very simple single board single purpose " defm $0d0a,"micro computer (EMUF) to demonstrate the usage of KIO's z80 engine " defm $0d0a,"to emulate a z80 system." defm $0d0a,"see enclosed documentation, c and z80 source for instructions for the " defm $0d0a,"eprom's monitor, for the emulator's menu items and how to implement " defm $0d0a,"the z80 engine into own emulators for z80 systems." defb $0a ; auskommentiert um roms vergleichbar zu machen: ; defm $0d0a,"this eprom was compiled with KIO's z80 assembler on ",__date__," at ",__time__ ; defb $0a defm $0d0a,"enter '?' to get help for the monitor" defm $0d0a defb 0 ; init "target application" ; and start monitor ld sp,(ram_top) ; target app's sp must be set to store target app's registers! idle_app ld hl,(tickercell) ; do just something call break_point jr idle_app ; ----------------------------------------------------------------------- ; THE MONITOR ; ----------------------------------------------------------------------- monitor: ld sp,ramstart+datasize ld hl,printhelp ; preset 'last cmd' ld (last_cmd),hl call printregisters moni rst printmsg ; prompt defm $0d0a,"> ",$00 ; get command mon1 rst readchar cp 13 jr z,again ; repeat last command cp ' ' jr c,mon1 ; no control char ... cp 127 jr nc,mon1 ; upper half of the room cleaning robot ; dispatch command cp '?' jp z,printhelp cp 'i' jp z,printinfo cp 'g' jp z,gosub ; no valid command found beep: rst printchar ; echo ld a,7 rst printchar jp moni ; repeat last command again: ld hl,(last_cmd) jp (hl) ; --------------------------------------------------------------------- ; call subroutine gosub: rst printmsg defm "gosub ",$00 call getnumber jr nz,moni ; abort cp a,enter jr nz,beep ; error call printspace ld de,gosub ; remember ld (last_cmd),de ld (last_addr),hl ld sp,(appl_sp) ; get target application registers exx ; gosub address -> hl pop af pop bc pop de pop hl ex af,af' exx pop ix pop iy pop af pop bc pop de ex hl,(sp) ; pop hl & push return address ret ; switch back to application context to_appl: ld sp,(appl_sp) pop af pop bc pop de pop hl ex af,af' exx pop ix pop iy pop af pop bc pop de pop hl ret ; continue application !!! ; ------------------------------------------------------------------------- ; remove breakpoint ; ein: -- ; mod: af ; ------------------------------------------------------------------------- clr_break push hl ld hl,(break_addr) ld a,h or l jr z,cbx ld a,(break_byte) ld (hl),a ld hl,0 ld (break_addr),hl cbx pop hl ret ; ------------------------------------------------------------------------- ; install breakpoint after actual instruction ; ein: hl = address of actual instruction ; mod: af ; ------------------------------------------------------------------------- nxt_break call opcode_len add a,l ld l,a jr nc,set_break inc h ; jr set_break ; ------------------------------------------------------------------------- ; install breakpoint ; ein: hl = address ; mod: af ; ------------------------------------------------------------------------- set_break call clr_break ld (break_addr),hl ld a,(hl) ld (break_byte),a ld (hl),$c7+breakpoint ret ; ------------------------------------------------------------------------- ; break point trap ; ------------------------------------------------------------------------- break_point push af call clr_break pop af ; switch to monitor context to_moni: push hl push de push bc push af push iy push ix exx ex af,af' push hl push de push bc push af ld (appl_sp),sp jp monitor ; continue monitor !!! ; -------------------------------------------------------------------------------------------- ; Calculate length of instruction (c) 1995-1996 KIO ! ; in: hl -> opcode ; 2nd byte of opcode is only inspected if 1st byte is a prefix ; IX/IY before IX/IY/ed have no effect and are reported as length 1 ; out: a = len ; mod: af ; -------------------------------------------------------------------------------------------- len0 defm "1311112111111121231111212111112123311121213111212331112121311121"; 0x00 - 0x3F len3 defm "1133312111303321113231211132302111313121113130211131312111313021"; 0xC0 - 0xFF; prefixes are 0 opcode_len: ld a,(hl) cp $40 jr nc,opl1 ; ----------------------> $00 - $3F: various length opl00 push hl ld hl,len0 jr opl9 ; ----------------------> $40 - $7F: load reg,reg: all 1 ; ----------------------> $80 - $BF: arithmetics/logics: all 1 opl1 ld a,(hl) cp $c0 jr nc,opl2 ld a,1 ret ; ----------------------> $c0 - $ff opl2 push hl ld hl,len3-$c0 opl9 add a,l ld l,a jr nc,$+3 inc h ld a,(hl) sub '0' pop hl ret nz ; ----------------------> prefix instruction ld a,(hl) ; opcode again cp a,$cb jp z,opl_2 ; prefix cb => all 2 byte cp a,$ed jr nz,opl_xy ; ----------------------> prefix ed => all 2 byte except 2nd byte = %01???011 opl_ed inc hl ld a,(hl) ; 2nd opcode byte dec hl and %11000111 cp a,%01000011 jr nz,opl_2 opl_4 ld a,4 ret opl_2 ld a,2 ret ; ----------------------> index instruction opl_xy inc hl ld a,(hl) ; 2nd opcode byte dec hl cp a,$40 jr c,oplxy0 cp $c0 jr nc,oplxy4 ; ----------------------> xy + $c0-$ff opl4 cp a,$cb jr z,opl_4 ; xy cb dis instr => all 4 bytes push hl ld hl,len3-$c0 add a,l ld l,a jr nc,$+3 inc h ld a,(hl) sub a,'0'-1 pop hl ; note: entries for prefixes are '0' giving a total of 1, ret ; just to skip the useless prefixes ix, iy and ed ; ----------------------> xy + $00-$3f oplxy0 cp a,$34 jr c,opl5 cp a,$37 jr nc,opl5 call opl00 add a,2 ret opl5 call opl00 inc a ret ; ----------------------> xy + $40-$bf ; if ( ((op2&0x07)==6) == ((op2&0x0F8)==0x70) ) return 2; else return 3 oplxy4 cp a,$76 jr z,opl_2 ; halt push af and a,7 cp a,6 jr z,opl31 ; source = (xy+dis) -> 3 byte pop af and $f8 cp $70 jr z,opl_3 ; target = (xy+dis) -> 3 byte jr opl_2 ; illegal -> 2 byte opl31 pop af opl_3 ld a,3 ret ; --------------------------------------------------------------------- ; display help message ; --------------------------------------------------------------------- printhelp: rst printmsg defm "? (help)",$00 ld hl,printhelp ld (last_cmd),hl rst printmsg defm $0d0a,"eprom monitor commands:" defm $0d0a," help show help page" defm $0d0a," display
display memory" defm $0d0a," modify
modify memory" defm $0d0a," gosub
call subroutine" defm $0d0a," breakpoint
set break point" defm $0d0a," register show & set register(s)" defm $0d0a," continue continue target application" defm $0d0a," single step execute next instruction" defm $0d0a," info display system info" defm $0d0a," repeats last command" defm $00 jp moni ; --------------------------------------------------------------------- ; display various system info ; --------------------------------------------------------------------- printinfo: halt halt halt call calcspeed ; calc speed first, because text output push de ; will slow down the engine push hl rst printmsg defm "info",$00 ld hl,printinfo ld (last_cmd),hl ; rst printmsg ; defm $0d0a,"eprom date = ",__date__,$00 rst printmsg defm $0d0a,"cpu speed = ",$00 pop hl call printdec ld a,'.' rst printchar pop hl call printdec3 rst printmsg defm " MHz",$00 rst printmsg defm $0d0a,"ram size = ",$00 ld hl,(ram_top) ld bc,ramstart and a sbc hl,bc call printdec rst printmsg defm $0d0a,"ticks since reset = ",$00 ld hl,(tickercell) call printdec jp moni ; ------------------------------------------------------------ ; print registers of target application ; ------------------------------------------------------------ printregisters: call printnl rst printmsg defm "A F BC DE HL IX IY SP PC I R irpt", $00 call printnl ld ix,(appl_sp) ld a,(ix+13) ; A call printhex2 call printspace ld c,(ix+12) ; F call print_f call printspace ld h,(ix+15) ; B ld l,(ix+14) ; C call printhex4 call printspace ld h,(ix+17) ; D ld l,(ix+16) ; E call printhex4 call printspace ld h,(ix+19) ; H ld l,(ix+18) ; L call printhex4 call printspace ld h,(ix+09) ; XH ld l,(ix+08) ; XL call printhex4 call printspace ld h,(ix+11) ; YH ld l,(ix+10) ; YL call printhex4 call printspace ld hl,(appl_sp) ld de,20 add hl,de ; SP call printhex4 call printspace ld h,(ix+21) ; PCH ld l,(ix+20) ; PCL call printhex4 call printspace ld a,i ; not preserved in context switch call printhex2 call printspace ld a,r ; mostly garbage call printhex2 call printspace ld a,i ; IFF jp po,pr2 rst printmsg defm "enabled",$00 jr pr1 pr2 rst printmsg defm "disabled",$00 pr1 call printnl ld a,(ix+1) ; A call printhex2 call printspace ld c,(ix+0) ; F call print_f call printspace ld h,(ix+3) ; B ld l,(ix+2) ; C call printhex4 call printspace ld h,(ix+5) ; D ld l,(ix+4) ; E call printhex4 call printspace ld h,(ix+7) ; H ld l,(ix+6) ; L jp printhex4 ; UP: print flag register ; in: c=flags print_f ld b,8 ld hl,flags pf2 ld a,(hl) inc hl rl c jr c,pf3 ld a,'-' pf3 rst printchar djnz pf2 ret flags defm 'SZ+H+VNC' ; ---------------------------------------------------------------- ; this is the end ; --------------------------------------------------------------------- ; defs epromsize-$,$ff ; fill to end of eprom #end