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1145
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1 **************************************************
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2 * System Call: F$Mem
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3 *
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4 * Function: Resize data memory area
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5 *
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6 * Input: D = Desired memory area (in bytes)
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7 *
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8 * Output: Y = Address of new memory area upper bound
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9 * D = New memory area size in bytes
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10 *
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11 * Error: CC = C bit set; B = error code
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12 *
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13 FMem ldx <D.Proc get current process pointer
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14 ldd R$D,u get requested memory size
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15 beq L0638 he wants current size, return it
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16 addd #$00FF round up to nearest page
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17 bcc L05EE no overflow, skip ahead
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18 ldb #E$MemFul get mem full error
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19 rts return
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20
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21 L05EE cmpa P$PagCnt,x match current page count?
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22 beq L0638 yes, return it
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23 pshs a save page count
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24 bhs L0602 he's requesting more, skip ahead
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25 deca subtract a page
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26 ldb #($100-R$Size) get size of default stack - R$Size
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27 cmpd P$SP,x shrinking it into stack?
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28 bhs L0602 no, skip ahead
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29 ldb #E$DelSP get error code (223)
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30 bra L0627 return error
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31 L0602 lda P$PagCnt,x get page count
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32 adda #$1F round it up
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33 lsra divide by 32 to get block count
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34 lsra
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35 lsra
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36 lsra
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37 lsra
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38 ldb ,s
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39 addb #$1F
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40 bcc L0615 still have room, skip ahead
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41 ldb #E$MemFul
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42 bra L0627
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43 L0615 lsrb divide by 32 to get block count
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44 lsrb
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45 lsrb
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46 lsrb
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47 lsrb
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48 IFNE H6309
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49 subr a,b same count?
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50 ELSE
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51 pshs b
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52 suba ,s+
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53 ENDC
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54 beq L0634 yes, save it
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55 bcs L062C overflow, delete the ram we just got
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56 os9 F$AllImg allocate the image in DAT
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57 bcc L0634 no error, skip ahead
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58 L0627 leas 1,s purge stack
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59 L0629 orcc #Carry set carry for error
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60 rts return
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61
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62 L062C equ *
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63 IFNE H6309
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64 addr b,a
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65 ELSE
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66 pshs a
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67 addb ,s+
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68 ENDC
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69 negb
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70 os9 F$DelImg
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71 L0634 puls a restore requested page count
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72 sta P$PagCnt,x save it into process descriptor
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73 L0638 lda P$PagCnt,x get page count
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74 clrb clear LSB
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75 std R$D,u save mem byte count to caller
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76 std R$Y,u save memory upper limit to caller
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77 rts return
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