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https://github.com/badvision/lawless-legends.git
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Hacked into PLASMA's memory accessors to give VM code transparent read/write access to main language card $E000.FFFF, and aux bank 1 language card $D000.DFFF.
This commit is contained in:
Martin Haye
parent
868837d040
commit
95c549984c
@ -35,6 +35,9 @@ pDst = $E ; len 2
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ucLen = $10 ; len 2
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checksum = $12 ; len 1
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plasmaNextOp = $F0 ; PLASMA's dispatch loop
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plasmaXTbl = $D300 ; op table for auXiliary code execution
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; Memory buffers
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fileBuf = $4000 ; len $400
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diskBuf = $4400 ; len $800
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@ -54,7 +57,7 @@ gcHash_dstHi = $5500
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prodosMemMap = $BF58
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;------------------------------------------------------------------------------
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; Relocate all the pieces to their correct locations
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; Relocate all the pieces to their correct locations and perform patching.
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relocate:
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; first our lo memory piece goes to $800
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ldy #0
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@ -152,10 +155,63 @@ relocate:
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bne .cpmm
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lda .st4+2
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cmp #$E0
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bcc init
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bcc +
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lda #"b"
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jsr cout
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brk ; mem mgr got too big!
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+
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; Patch PLASMA's memory accessors to gain access to writing main LC, and
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; to read/write bank 2 in aux LC.
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; first copy the stub code into PLASMA's bank
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bit setLcRW+lcBank2 ; PLASMA's bank
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ldx #(plasmaAccessorsEnd-plasmaAccessorsStart-1)
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- lda plasmaAccessorsStart,x
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sta LBXX,x
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dex
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bpl -
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; now record PLASMA's original routines, and patch it to call our stubs
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lda plasmaXTbl+$60 ; LBX
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sta oLBX+1
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lda #<LBXX
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sta plasmaXTbl+$60
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lda plasmaXTbl+$61
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sta oLBX+2
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lda #>LBXX
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sta plasmaXTbl+$61
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lda plasmaXTbl+$62 ; LWX
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sta oLWX+1
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lda #<LWXX
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sta plasmaXTbl+$62
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lda plasmaXTbl+$63
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sta oLWX+2
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lda #>LWXX
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sta plasmaXTbl+$63
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lda plasmaXTbl+$70 ; SBX
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sta oSBX+1
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lda #<SBXX
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sta plasmaXTbl+$70
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iny
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lda plasmaXTbl+$71
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sta oSBX+2
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lda #>SBXX
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sta plasmaXTbl+$71
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lda plasmaXTbl+$72 ; SWX
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sta oSWX+1
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lda #<SWXX
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sta plasmaXTbl+$72
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iny
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lda plasmaXTbl+$73
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sta oSWX+2
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lda #>SWXX
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sta plasmaXTbl+$73
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; fall through into init...
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;------------------------------------------------------------------------------
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init: !zone
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@ -312,6 +368,57 @@ init: !zone
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ldx #$10 ; initial eval stack index
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.gomod: jmp $1111 ; jump to module for further bootstrapping
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;------------------------------------------------------------------------------
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; Special PLASMA memory accessors
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plasmaAccessorsStart:
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!pseudopc $DF00 {
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; Plasma load byte/word with special handling for $D000.DFFF in aux language card
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LBXX: !zone {
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clv ; clear V to denote LBX (as opposed to LWX)
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bvc .shld ; always taken
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LWXX: bit monrts ; set V to denote LWX (not LBX)
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.shld lda evalStkH,x ; hi byte of address to load from
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cmp #$D0
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bcc .norm
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cmp #$E0
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bcs .norm
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sty tmp
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jsr l_LXXX ; helper function in low memory because it switches us out (we're in main LC)
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ldy tmp
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jmp plasmaNextOp
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.norm bvs oLWX
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oLBX: jmp $1111 ; modified to be addr of original LBX
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oLWX: jmp $1111 ; modified to be addr of original LWX
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} ; zone
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; Plasma store byte/word with special handling for $D000.DFFF and $E000.FFFF
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SBXX: !zone {
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clv ; clear V to denote SBX (as opposed to SWX)
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bvc .shst ; always taken
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SWXX: bit monrts ; set V to denote SWX (not SBX)
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.shst lda evalStkH+1,x ; get hi byte of pointer to store to
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cmp #$D0 ; in $0000.CFFF range,
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bcc .norm ; just do normal store
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bit setLcRW+lcBank2 ; PLASMA normally write-protects the LC,
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bit setLcRW+lcBank2 ; but let's allow writing there
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cmp #$E0 ; in $E000.FFFF range do normal store after write-enable
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bcs .norm
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sty tmp
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jsr l_SXXX ; helper function in low memory because it switches us out (we're in main LC)
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ldy tmp
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inx
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inx
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jmp plasmaNextOp
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.norm bvs oSWX
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oSBX: jmp $1111 ; modified to be addr of original SBX
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oSWX: jmp $1111 ; modified to be addr of original SWX
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} ; zone
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} ; pseudopc
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plasmaAccessorsEnd:
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;------------------------------------------------------------------------------
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; Vectors and debug support code - these go in low memory at $800
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loMemBegin: !pseudopc $800 {
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@ -450,6 +557,47 @@ exitProDOS: !zone
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; manager lives, and it's the only code that calls ProDOS.
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rti ; RTI pops P-reg and *exact* return addr (not adding 1)
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;------------------------------------------------------------------------------
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; Replacement memory accessors for PLASMA, so we can utilize language card mem
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; including the hard-to-reach aux-bank $D000.DFFF
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l_LXXX: !zone {
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sta .ld+2
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lda evalStkL,x
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sta .ld+1
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sta setAuxZP
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ldy #1
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.ldlup sta .lhb+1
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.ld lda $1111,y ; self-modified above
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dey
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bne .ldlup
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sta clrAuxZP
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sta evalStkL,x
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bvc +
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.lhb lda #11 ; self-modified above
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sta evalStkH,x
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+ rts
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}
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l_SXXX: !zone {
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sta .st+2 ; in $D000.DFFF range, we jump through hoops to write to AUX LC
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lda evalStkL+1,x ; lo byte of pointer
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sta .st+1
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lda evalStkH,x ; hi byte of value to store
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sta .shb+1
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lda evalStkL,x ; lo byte of value
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sta setAuxZP ; switch to aux LC
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+ ldy #0
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.st sta $1111,y ; self-modified above
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bvc + ; for SBX, don't write hi byte
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.shb lda #11 ; self-modified above
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iny
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cpy #2
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bne .st ; loop to write hi byte also
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+ sta clrAuxZP ; back to main LC
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rts
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}
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;------------------------------------------------------------------------------
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; Utility routine for convenient assembly routines in PLASMA code.
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; Params: Y=number of parameters passed from PLASMA routine
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@ -897,14 +1045,14 @@ gc1_mark: !zone
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bvc .start
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; Phase 3 of Garbage Collection: fix all pointers
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gc3_fix:
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bit .rts ; set V flag to mark phase 3
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bit monrts ; set V flag to mark phase 3
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.start lda #0
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sta resNum ; initialize block counter (note: blk #0 in hash is not used)
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.outer inc resNum ; advance to next block in hash
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ldx resNum
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cpx gcHash_top ; finished all blocks?
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beq .trav ; last blk? if so still need to trav it
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bcs .rts ; or if past last blk, we're done
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bcs .done ; or if past last blk, we're done
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.trav ldy gcHash_srcLo,x ; get pointer to block, lo byte first
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lda gcHash_srcHi,x ; then hi byte
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bvc +
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@ -947,7 +1095,7 @@ gc3_fix:
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+ ldx tmp+1 ; restore type entry index
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inx ; next offset entry
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bne .ldof ; always taken
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.rts rts ; this needs to be an RTS instruction - used to set V flag
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.done rts
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.corrup jmp heapCorrupt
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; Phase 2 of Garbage Collection: sweep all accessible blocks together
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@ -1553,8 +1553,6 @@ def findTestString(len)
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for t = 1 to len
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p2 = p2+1
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printf1("Setting %x to 'X'\n", p2)
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^$c083
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^$c083
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p2->0 = 'X'
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next
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return p
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