;************************************************************************** ;** ;** booter.asm ;** Copyright (c) 1995,1996 Daniel Kahlin ;** ;****** PROCESSOR 6502 ;zeropage definitions currzp EQU $fb ;WORD destzp EQU $ae ;WORD relzp EQU $fd ;WORD jmpaddr EQU $0110 ;WORD rtsaddr EQU $0110 ;BYTE ytmp EQU $ac ;BYTE checksumzp EQU $ad ;BYTE codezp EQU $ac ;BYTE HASH_DISTANCE EQU 32 org $4711 ;should not matter at all booter_start: ;************************************************************************** ;** ;** unstuffer ;** Fully relocatable & machine independant code. ;** ;****** unstuffer: ;*** ;*** do unstuffing of code ;*** this code may not contain any zeroes!!! ;*** sei lda #$ff ;MUST be! code is inserted here by Over5 sta codezp ;* ;* special code for relative addressing ;* fucks up if NMI occurs somewhere ;* lda #$60 sta rtsaddr jsr rtsaddr reladdrstuffer: tsx dex dex lda.wx [$0100+1],x clc adc #booterstuff_OFFSET sta currzp lda.wx [$0100+2],x sta currzp+1 bcc us_skp4 inc currzp+1 us_skp4: ;* ;* decide where to put the code. ;* always put us at MEMTOP-$420 (should work on most cbm machines) ;* When RS-232 is opened later on kernal lowers MEMTOP automatically ;* to provide space for buffers (512 bytes). We ourselves take $200 ;* bytes. $20 extra is for good measure ;* SPACE EQU $0420 sec jsr $ff99 ;MEMTOP txa sec sbc #SPACE sta destzp+1 sta jmpaddr+1 ldx #2 ;number of pages ldy #1 ;y=0 dey ;* ;* the unstuff loop ;* us_lp1: lda (currzp),y cmp codezp bne us_skp1 sec sbc codezp ;A=0 without any zeros. us_skp1: sta (destzp),y iny bne us_lp1 inc currzp+1 inc destzp+1 dex bpl us_lp1 jmp (jmpaddr) ;*** ;*** stuff tag! MUST be here! Tells Over5 to start stuffing after ;*** this mark. ;*** nop nop ;*** ;*** from here it's ok to have zeroes in the code. ;*** ;************************************************************************** ;** ;** booter ;** Fully relocatable & machine independant code. ;** ;****** booter_stuff: booterstuff_OFFSET EQU [booter_stuff-reladdrstuffer]+1 ;* ;* produce code with origin $0000 ;* so that we can just add the base address to all ;* references ;* RORG $0000 reladdr: lda jmpaddr sta relzp lda jmpaddr+1 sta relzp+1 ;* ;* relocate ourselves ;* ldy #table_OFFSET bt_lp1: ldx #1 lda (relzp),y clc adc relzp sta currzp iny lda (relzp),y bpl bt_skp1 ldx #2 bt_skp1: and #$7f adc relzp+1 sta currzp+1 iny sty ytmp ldy #0 lda (currzp),y clc adc relzp sta (currzp),y txa tay lda (currzp),y adc relzp+1 sta (currzp),y ldy ytmp cpy #tableend_OFFSET bne bt_lp1 rel_iw0: jmp theprogram ;************************************************************************** ;** ;** relocation tables ;** ;****** MAC RELINSTR IFCONST rel_ilh{1} dc.w [rel_ilh{1}+1]|$8000 ELSE dc.w [rel_iw{1}+1] ENDIF ENDM table: RELINSTR 0 RELINSTR 1 RELINSTR 2 RELINSTR 3 RELINSTR 4 RELINSTR 5 RELINSTR 6 RELINSTR 7 RELINSTR 8 RELINSTR 9 RELINSTR 10 RELINSTR 11 RELINSTR 12 RELINSTR 13 RELINSTR 14 RELINSTR 15 RELINSTR 16 tableend: table_OFFSET EQU [table-reladdr] tableend_OFFSET EQU [tableend-reladdr] ;************************************************************************** ;** ;** theprogram ;** when entering here we are located at somewhere around MEMTOP-$420 and ;** all absolute references has (hopefully) been relocated. ;** ;****** theprogram: cli rel_ilh1: ldx #start_MSG rel_iw2: jsr bt_print jsr $ffcc ;CLRCHN jsr $ffe7 ;CLALL ;* ;* open a RS232 channel ;* lda #2 ldx #2 ldy #3 jsr $ffba ;SETLFS lda #sernameend-sername rel_ilh3: ldx #sername jsr $ffbd ;SETNAM jsr $ffc0 ;OPEN ;* ;* set RS232 as the default input ;* ldx #2 jsr $ffc6 ;CHKIN ;* ;* sync receiver ;* bt_lp2: rel_iw4: jsr bt_rawgetbyte cmp #"S" bne bt_lp2 bt_lp3: rel_iw5: jsr bt_rawgetbyte cmp #"S" beq bt_lp3 ;* ;* Flush ST, and reset checksum ;* jsr $ffb7 ;READST lda #0 sta checksumzp ;* ;* synced ;* now get mem bottom ;* sec jsr $ff9c ;MEMBOT txa clc adc #1 sta destzp tya adc #0 sta destzp+1 ;* ;* Get the data ;* $11,$11 -> $11 $11,$80 -> $00 $11,$01 -> END ;* ldx #HASH_DISTANCE ldy #0 bt_lp4: rel_iw6: jsr bt_getbyte cmp #$11 bne bt_skp5 rel_iw7: jsr bt_getbyte cmp #$80 beq bt_skp2 cmp #$11 beq bt_skp5 cmp #$01 ;endmark beq bt_skp4 rel_iw8: jmp bt_failchecksum bt_skp2: lda #0 bt_skp5: sta (destzp),y inc destzp bne bt_skp3 inc destzp+1 bt_skp3: dex bne bt_lp4 lda #"#" jsr $ffd2 ldx #HASH_DISTANCE bne bt_lp4 ;always ;* ;* end of data ;* setup basic end. ;* bt_skp4: lda destzp sta $2d ;end of basic program lda destzp+1 sta $2e ;end of basic program ;* ;* receive checksum ;* rel_iw9: jsr bt_getbyte rel_iw10: jsr bt_getbyte lda checksumzp bne bt_failchecksum ;* ;* it went ok! ;* rel_ilh11: ldx #allok_MSG rel_iw12: jsr bt_print bt_ex1: ;* ;* close RS232 and terminate ;* jsr $ffcc ;CLRCHN lda #2 jsr $ffc3 ;CLOSE ;* ;* 'READY.' has already been printed. ;* set direct mode, ;* set stack and jump through the basic main loop vector ;* lda #$80 jsr $ff90 ;SETMSG ldx #$fa txs jmp ($0302) ;IMAIN ;* ;* failure exit ;* Just outputs '?transfer error' ;* bt_failchecksum: bt_failserial: rel_ilh13: ldx #error_MSG rel_iw14: jsr bt_print rel_iw15: jmp bt_ex1 ;************************************************************************** ;** ;** print ;** prints a NULL terminated string pointed to by X/Y ;** always returns Z=1 ;** ;****** bt_print: stx currzp sty currzp+1 ldy #0 btp_lp1: lda (currzp),y beq btp_ex1 jsr $ffd2 ;CHROUT iny bne btp_lp1 btp_ex1: rts ;************************************************************************** ;** ;** getbyte ;** ;** get a byte from RS232, calculate checksum, exit if errors ;** ;****** bt_getbyte: rel_iw16: jsr bt_rawgetbyte pha clc adc checksumzp sta checksumzp jsr $ffb7 ;READST and #$f7 bne bt_failserial pla rts ;************************************************************************** ;** ;** rawgetbyte ;** ;****** bt_rawgetbyte: btrgb_lp1: jsr $ffe4 ;GETIN cmp #0 beq btrgb_lp1 rts ;************************************************************************** ;** ;** booter data ;** ;****** sername: ;600 baud dc.b %00000111,%00000000 sernameend: start_MSG: dc.b 13,13,"* STAGE 2 *",13,0 error_MSG: dc.b 13,"?TRANSFER ERROR",13,"READY.",13,0 allok_MSG: dc.b 13,"OK, NOW SAVE TO DISK!",13,13,"READY.",13,0 REND ds.b [booter_start+$200]-.,$ea booter_end: