sw/rescue/lab8e_goettingen/disk2_11/rka/paroff/randu.ra

   1 /       SUBROUTINE RANDU
   2 /       THE RANDOM GENERATOR IS THAT FROM DECUS 5-25
   3 /       MUST BE USED IN PDP8 CODE AS IT DOES SOME ILLEGAL ARITHMETIC
   4 /
   5 /       USAGE
   6 /       CALL RANDU (IX,F)
   7 /       IX IS ANY NUMBER:
   8 /       IF SET TO A FIXED NUMBER ON FIRST ENTRY A REPEATABLE SEQUENCE
   9 /       IS GENERATED
  10 /       BUT NOTE THAT ALL PARTS OF THE NUMBER MUST BE DEFINED
  11 /       IE USE IX>1 AND 5-6 DIGITS
  12 /       IF SET TO 0 A RANDOM NUMBER SEQUENCE IS INITIATED
  13 /       NOTE THAT THIS SEQUENCE IS DEPENDENT OF THE BACKGOUND
  14 /       JOB.
  15 /       CALLING WITH THE SAME TIMING PARAMETERS MIGHT RESULT
  16 /       IN REPETITION OF SAME SEQUENCE.
  17 /       ALSO FIRST CALL TO RANDU SETS UP BACKGROUND JOB
  18 /       AND A 0 CALL AT THAT TIME IS NOT RANDOM
  19 /
  20 /       COORECT SEQUENCE TO GET A RANDOM START
  21 /
  22 /       I=0
  23 /       CALL RANDU(IX,X)        NOTE RANDU CHANGES I
  24 /       WRITE (0,..... TTY  OUTPUT (OR INPUT)  GIVES A 'RANDOM START'
  25 /       I=0
  26 /       CALL RANDU (IX,X) X IS RANDOM
  27 /       CALL RANDU (IX,X) KEEP SAME I
  28 /       ON SUBSEQUENT CALLS IT SHOULD BE LEFT UNTOUCHED
  29 /***    NOTE  IX IS A NOT NORMAL FPP NUMBER IT SHOULD NOT BE USED IN FPP
  30 /       ARITHMETIC ***
  31 /       F IS ON RETURN A RANDOM NUMBER BETWEEN 0 AND 1
  32 \f       SECT    RANDU
  33         JA      #ST
  34 #XR,    ORG     .+10
  35         TEXT    'RANDU'
  36 #RET,   SETX    #XR
  37         SETB    #BASE
  38         JA      .+3
  39 #BASE,  ORG     .+6
  40 I,      ORG     .+3
  41 F,      ORG     .+3
  42         ORG     #BASE+30
  43         FNOP
  44         JA      #RET
  45         FNOP
  46 #GOBAK, 0;0
  47 #LBL=.
  48         ORG     #LBL
  49 #RTN,   BASE    #BASE
  50         JA      #GOBAK
  51 #ST,    STARTD
  52         0210
  53         FSTA    #GOBAK,0
  54         0200
  55         SETX    #XR
  56         SETB    #BASE
  57         LDX     0,1
  58         FSTA    #BASE
  59         FLDA%   #BASE,1+
  60         FSTA    I
  61         FLDA%   #BASE,1+
  62         FSTA    F
  63         STARTF
  64         FLDA    TWIDD           / IS THIS FIRST CALL
  65         JNE     NOTFIR
  66         TRAP4   #FIRST          / YES, INITIATE BACKGROUND LOOP
  67 NOTFIR, FLDA%   I
  68         JNE     #G0001
  69         FLDA    TWIDD           / FETCH TWIDDLER CONSTANTS
  70         FSTA%   I               / AND USE AS START OF RANDOM
  71 #G0001, FSTA    L               / PLACE TO SECT 8
  72         TRAP4   #RANDU          / GO GENERATE NEW NUMBER
  73         FLDA    L               / FOR NEXT ITERATION
  74         FSTA%   I
  75         FLDA    T               / NEW RANDOM NUMBER IE L WITH HIGH ORDER=0
  76         JGT     POS
  77         FNEG                    / SHOULD BE 0-1
  78 POS,    FSTA%   F
  79         JA      #RTN
  80 \f/      THE RANDOM GENERATOR
  81 /       ON CALLING L=OLD RANDOM NR
  82 /       ON EXIT L=NEW NUMBER
  83 /       THE 2 LOW ORDER PARTS OF THIS ARE MOVED TO T
  84         SECT8   #RAND8
  85 #RANDU, 0
  86         TAD     L3
  87         SNA                     / ALL PARTS MUST BE NON ZERO
  88         TAD     .               / NICE CONSTANT
  89         RAL
  90         AND     R7400
  91         DCA     T3
  92         TAD     L2
  93         SNA
  94         TAD     .               / NICE CONSTANT ?
  95         AND     R177
  96         TAD     T3
  97         RTL
  98         RTL
  99         RAL
 100         DCA     T1
 101         TAD     L3
 102         AND     R177
 103         RTL
 104         RTL
 105         RAL
 106         TAD     L2
 107         DCA     T2
 108         SZL
 109         ISZ     T1
 110         NOP
 111         TAD     L3
 112         CLL RAL
 113         SZL
 114         ISZ     T2
 115         SKP
 116         ISZ     T1
 117         NOP
 118         CLL
 119         TAD     L3
 120         DCA     L3
 121         TAD     L2
 122         RAL
 123         SZL
 124         ISZ     T1
 125         NOP
 126         CLL
 127         TAD     T2
 128         DCA     L2
 129         TAD     L1
 130         SNA
 131         TAD     .
 132         RAL
 133         TAD     L1
 134         TAD     T1
 135         DCA     L1
 136 /       END OF GENERATOR
 137         TAD     L1              / WE ONLY WANT WORD 2 AND 3
 138         DCA     T2
 139         DCA     T1
 140         TAD     L2
 141         DCA     T3
 142         CDF CIF 0
 143         JMP%    #RANDU
 144 T,                              / OLD RANDOM NUMBER, START OF NEXT
 145 T1,     0
 146 T2,     0
 147 T3,     0
 148 L,                              / NEW RANDOM NUMBER
 149 L1,     0
 150 L2,     0
 151 L3,     0
 152 R177,   177
 153 R7400,  7400
 154         EXTERN  ONQB
 155 #FIRST, 0                       / INITIATE BACKGROUND
 156         JMS%    XONQB+1
 157         ADDR    LOOP
 158         ISZ     TW1
 159         ISZ     TW2
 160         ISZ     TW2             / NOT ALL =0
 161         CDF CIF 0
 162         JMP%    #FIRST
 163 TWIDD,
 164 TW1,    0
 165 TW2,    0
 166 TW3,    0
 167 LOOP,   0
 168         ISZ     TW1
 169         ISZ     TW2
 170         ISZ     TW3
 171         NOP
 172         CDF CIF 10
 173         JMP%    LOOP
 174 XONQB,  ADDR    ONQB
 175         END
 176 \1a