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1345
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1 **************************************************
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2 * System Call: F$AllRAM
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3 *
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4 * Function: Allocate RAM blocks
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5 *
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6 * Input: B = Desired block count
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7 *
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8 * Output: D = Beginning RAM block number
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9 *
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10 * Error: CC = C bit set; B = error code
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11 *
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1387
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12 FAllRAM ldb R$B,u Get # blocks requested
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1145
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13 pshs b,x,y Save regs
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14 ldx <D.BlkMap Get ptr to start of block map
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15 L0974 leay ,x Point Y to current block
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16 ldb ,s Get # blocks requested
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17 L0978 cmpx <D.BlkMap+2 Hit end of map yet?
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18 bhs L0995 Yes, exit with No RAM error
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19 lda ,x+ Get block marker
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20 bne L0974 Already used, start over with next block up
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21 decb Dec # blocks still needed
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22 bne L0978 Still more, keep checking
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23 * Entry: Y=ptr to start of memory found
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24 * Note: Due to fact that block map always starts @ $200 (up to $2FF), we
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25 * don't need to calc A
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26 L0983 tfr y,d Copy start of requested block mem ptr to D (B)
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27 lda ,s Get # blocks requested
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28 stb ,s Save start block #
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29 L098D inc ,y+ Flag blocks as used
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30 deca (for all blocks allocated)
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31 bne L098D Do until done
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32 puls b Get start block #
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33 clra (allow for D as per original calls)
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34 std R$D,u Save for caller
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35 puls x,y,pc Restore regs & return
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36
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37 L0995 comb Exit with No RAM error
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1387
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38 ldb #E$NoRAM
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1145
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39 stb ,s
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40 puls b,x,y,pc
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41
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1345
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42
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43 **************************************************
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44 * System Call: F$AlHRAM
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45 *
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46 * Function: Allocate RAM blocks from top of RAM
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47 *
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48 * Input: B = Desired block count
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49 *
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50 * Output: D = Beginning RAM block number
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51 *
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52 * Error: CC = C bit set; B = error code
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53 *
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1387
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54 FAlHRAM ldb R$B,u Get # blocks to allocate
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1145
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55 pshs b,x,y Preserve regs
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56 ldx <D.BlkMap+2 Get ptr to end of block map
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57 L09A9 ldb ,s Get # blocks requested
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58 L09AB cmpx <D.BlkMap Are we at beginning of RAM yet?
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59 bls L0995 Yes, exit with No RAM error
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60 lda ,-x Get RAM block marker
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61 bne L09A9 If not free, start checking next one down
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62 decb Free block, dec # blocks left to find count
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63 bne L09AB Still more needed, keep checking
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64 tfr x,y Found enough contigous blocks, move ptr to Y
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65 bra L0983 Go mark blocks as used, & return info to caller
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66
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