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1145
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1 * F$LDAXY entry point
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2 FLDAXY ldx R$X,u Get offset within block (S/B $0000-$1FFF)
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3 ldy R$Y,u Get ptr to DAT block entry
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4 bsr L0AC8 Go get byte
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5 sta R$A,u Save in caller's A reg.
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6 rts
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7
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8 * Entry: X=offset ($0000-$1fff) to get from block pointed to by Y (DAT entry
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9 * format)
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10 L0AC8 lda 1,y Get MMU block # to get data from
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11 clrb Clear carry/setup for STB
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12 pshs cc Preserve interrupt status/settings
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13 orcc #IntMasks shut IRQ's off
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14 sta >$FFA0 Map block into $0000-$1FFF
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15 brn L0AC8
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16 lda ,x Get byte
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17 stb >$FFA0 Map block 0 into $0000-$1FFF
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1239
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18 fdb $21ED LBRN ???
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1145
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19 puls pc,cc Get interrupt status/(or turn on) & return
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20
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21 * Get 1st byte of LDDDXY - also used by many other routines
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22 * Increments X on exit; adjusts X for within 8K block & Y (DAT img ptr)
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23 LDAXY lda 1,y Get MMU block #
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24 pshs b,cc
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25 clrb
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26 orcc #IntMasks Shut off interrupts
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27 sta >$FFA0 Map in MMU block into slot 0
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28 lda ,x+ Get byte
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29 stb >$FFA0
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30 * clr >$FFA0 Map in MMU block #0 into slot 0
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31 * andcc #^IntMasks
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32 puls b,cc
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33 bra AdjBlk0
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34
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35 L0AEA leax >-DAT.BlSz,x Bump offset ptr to start of block again
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36 leay 2,y Bump source MMU block up to next on in DAT Image
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37 AdjBlk0 cmpx #DAT.BlSz Going to wrap out of our block?
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38 bhs L0AEA Yes, go adjust
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39 rts No, return
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40
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41 * F$LDDDXY entry point
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42 FLDDDXY ldd R$D,u Get offset to offset within DAT Image
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43 leau R$X,u Point U to Offset
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44 pulu x,y Y=Offset within DAT Image, X=DAT Image ptr
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45 bsr L0B02 Go get 2 bytes
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46 std -(R$X+3),u Save into caller's X
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47 clrb No error & return
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48 rts
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49 * Get 2 bytes for LDDDXY (also called by other routines)
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50 * Should simply map in 2 blocks, and do a LDD (don't have to worry about wrap)
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51 L0B02 pshs u,y,x Preserve regs
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52 IFNE H6309
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53 addr d,x Point X to X+D
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54 ELSE
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55 leax d,x
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56 ENDC
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57 bsr AdjBlk0 Wrap address around for 1 block
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58 ldu <D.SysDAT Get sys DAT Image ptr
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59 * lda 1,u Get MMU block #0
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60 clra system block 0 =0 always
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61 ldb 3,u Get MMU block #1
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62 tfr d,u make U=blocks to re-map in once done
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63 lda 1,y Get MMU block #0
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64 ldb 3,y Get MMU block #1
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65 pshs cc Preserve int. status
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66 orcc #IntMasks shut off int.
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67 std >$FFA0 Map in both blocks
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68 ldd ,x Get 2 bytes
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69 stu >$FFA0 Map original blocks in
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70 * tfr y,w Restore W
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71 puls pc,u,y,x,cc Restore regs & return
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