intermediate check-in

diff --git a/libsrc/atari/shadow_ram_handlers.s b/libsrc/atari/shadow_ram_handlers.s
index e2de0c31936f83a2dcef21799fb095e04f972238..564568130dfa5de22e2f85b561c1c02bcbf63f1d 100644 (file)
--- a/libsrc/atari/shadow_ram_handlers.s
+++ b/libsrc/atari/shadow_ram_handlers.s
@@ -4,6 +4,7 @@
 ; Christian Groessler, chris@groessler.org, 2013
 ;
 
+
 .if .defined(__ATARIXL__)
 
         .include        "atari.inc"
@@ -13,15 +14,24 @@
        .export         sram_init
        .export         KEYBDV_wrapper
 
+BUFSZ          =       128
+BUFSZ_CIO      =       BUFSZ
+BUFSZ_SIO      =       BUFSZ
+
 .macro disable_rom
+       .local  cont
+       ;dec    enable_count
+       ;bne    cont
        lda     PORTB
        and     #$fe
        sta     PORTB
        lda     #>__CHARGEN_START__
        sta     CHBAS
        sta     CHBASE
+cont:
 .endmacro
 .macro enable_rom
+       ;inc    enable_count
        lda     PORTB
        ora     #1
        sta     PORTB
@@ -32,6 +42,8 @@
 
 .segment "INIT"
 
+enable_count:  .res    1
+
 ; Turn off ROMs, install system and interrupt wrappers, set new chargen pointer
 
 sram_init:
@@ -42,6 +54,8 @@ sram_init:
        stx     NMIEN           ; disable NMI
 
 ; disable ROMs
+       ;inx
+       stx     enable_count
        disable_rom
 
 ; setup interrupt vectors
@@ -82,8 +96,24 @@ sram_init:
        rts
 
 
+.segment "LOWBUFS"
+
+; bounce buffers for CIO and SIO calls
+CIOV_buffer:   .res    BUFSZ_CIO
+SIOV_buffer:   .res    BUFSZ_SIO
+
+
 .segment "LOWCODE"
 
+; Interrupt handlers
+; ------------------
+
+; The interrupt handlers don't look at the current state of PORTB and
+; unconditionally disable the ROMs on exit.
+; Please note that this works, since if the ROMs are enabled we anyway
+; aren't being called here because the vectors are pointing to their
+; original ROM locations.
+
 .macro int_wrap orgvec
        .local  ret
        pha
@@ -109,35 +139,139 @@ my_RESET_han:
        int_wrap RESET_save
 
 
+; System request handlers
+; -----------------------
+
+; CIO handler
+; We have buffer pointer and length entries in the IOCB, but their
+; usage depends on the function.
+; Some functions don't care about both (pointer and length), and some
+; only use the pointer (like e.g. OPEN), and some use both.
+; So we need function specific handlers to correctly deal with
+; buffers which are overlapping with the ROM area.
+; All input and output registers need to be preserved (I'm not 100%
+; sure about Y, but let's preserve it for now.)
+;
+; FIXME: Currently only the requests used by the runtime lib are handled.
+
 my_CIOV:
+
+; @@@ TODO: check X for valid IOCB index ((X < $80) and ((X & $F) == 0))
+
+       sta     CIO_a
+       sty     CIO_y
+       stx     CIO_x
+
+       lda     ICCOM,x                 ; get function
+       cmp     #OPEN
+       beq     CIO_filename            ; filename as input parameter in buffer, length not used
+       cmp     #PUTREC
+       bcc     CIO_read                ; input (GETREC or GETCHR)
+       cmp     #CLOSE
+       bcc     CIO_write               ; output (PUTREC or PUTCHR)
+       beq     CIO_pass                ; pass through, buffer not used
+       cmp     #RENAME                 ; 2 filenames as input parameters in buffer, length not used
+       beq     CIO_filename2
+       cmp     GETCWD
+       bcc     CIO_filename            ; filename as parameter in buffer, length not used
+       beq     CIO_read                ; input
+       bcs     CIO_pass                ; other command: assume no buffers
+
+
+
+.if 0          ; all crap
+; check if buffer is potentially used (buffer length != 0)
+
        pha
+       lda     ICBLL,x
+       ora     ICBLH,x
+       bne     could_be
+       pla
+       jmp     CIOV_call
+
+; buffer might be used by the request
+
+could_be:
+
+; check if buffer is inside ROM area
+
+       lda     ICBAH,x
+       cmp     #$C0                    ; if buffer is above $C000, it's definitely inside ROM area
+       bcs     need_work
+
+       lda     ICBAL,x                 ; low byte of buffer address
+       adc     ICBLL,x                 ; low byte of buffer length
+       lda     ICBAH,x                 ; high byte (address)
+       adc     ICBLH,x                 ; high byte (length)
+       cmp     #$C0
+       bcc     CIOV_call               ; no need to use bounce buffers, just forward call to CIO
+
+need_work:
+
+; Check if length is bigger than the size of our bounce buffer.
+; If yes, we need to split the call into multiple calls.
+; @@@ FIXME: currently only supports bounce buffers < 256 bytes
+
+       lda     ICBLH,x                 ; high byte of length
+       bne     hard_work
+       lda     ICBLL,x                 ; low byte of length
+       cmp     #<BUFSZ_CIO
+       beq     little_work
+       bcs     hard_work
+
+; Request buffer is smaller or equal to our bounce buffer.
+; Copy the data into the bounce buffer, set bounce buffer address
+; in the IOCB, call CIO, and copy the output data back.
+; @@@ TODO: check for read/write and do only one of the copy operations
+little_work:
+
+
+
+; Request buffer is larger than our bounce buffer.
+hard_work:
+
+.endif ; crap alert
+
+CIOV_call:
+       pha
+       lda     PORTB
+       sta     cur_CIOV_PORTB
        enable_rom
        pla
        jsr     CIOV_org
        php
        pha
-       disable_rom
+       lda     cur_CIOV_PORTB
+       sta     PORTB
        pla
        plp
        rts
 
+
 my_SIOV:
        pha
+       lda     PORTB
+       sta     cur_SIOV_PORTB
        enable_rom
        pla
        jsr     SIOV_org
        php
        pha
-       disable_rom
+       lda     cur_SIOV_PORTB
+       sta     PORTB
        pla
        plp
        rts
 
+
 KEYBDV_wrapper:
+
        lda     #>(kret-1)
        pha
        lda     #<(kret-1)
        pha
+       lda     PORTB
+       sta     cur_KEYBDV_PORTB
        enable_rom
        lda     KEYBDV+5
         pha
@@ -145,8 +279,13 @@ KEYBDV_wrapper:
         pha
        rts             ; call keyboard handler
 kret:  pha
-       disable_rom
+       lda     cur_KEYBDV_PORTB
+       sta     PORTB
        pla
        rts
 
+cur_CIOV_PORTB:                .res    1
+cur_SIOV_PORTB:                .res    1
+cur_KEYBDV_PORTB:      .res    1
+
 .endif ; .if .defined(__ATARIXL__)