I have been busy doing the "extending the precision" of the algorithms, I coded a simulator for an extended version of the Saturn. I did change the encoding, P has now 5 bits instead of 4. And there are some extra registers.
Calculating the square root of 5 needs as you can guess double the amount of executed opcodes as in the original Saturn.
All the code to the experiment, called Parallel Neptune Core, can be found
here.
The source file of the sqrt function with the equivalent Saturn code follows:
Code:
1 ;
2 ; Number format extended form
3 ;
4 ;
5 ; | <------ A ------> |
6 ; | <-- X --> |
7 ; | XS|
8 ; WS-1 4 3 2 1 0
9 ; +---+--- ... ---+---+---+---+---+---+
10 ; A/C | S | | S | E | E | E | E |
11 ; +---+--- ... ---+---+---+---+---+---+
12 ;
13 ; +---+--- ... ---+---+---+---+---+---+
14 ; B/D | 0 | WS - 2 digits significand |
15 ; +---+--- ... ---+---+---+---+---+---+
16 ;
17 ; 9 as Significand sign means negative number
18 ; Digits 5..9 as exponent sign means negative exponent
19
20 000000 2000001E loadp #30 ; P= 14
21 000001 31300005 ldn b,#5 ; LC(1) #5
22
23
24 ;
25 ; SQRT
26 ;
27 ; A exponent in A field
28 ; B significand in m field
29 ;
30 ;
31 ;
32 ;
33 ;
34 ;
35 ;
36
37 SQRT_Full: ;
38 ; =SQR15
39 ; XM=0
40 ; SB=0
41 ; SETHEX
42 ; A=A+1 XS
43 ; A=A-1 XS
44 ; SETDEC
45 ; GONC =SQR17
46 ; ?A#0 B
47 ; RTNYES
48 ; ?A#0 S
49 ; GOYES L_0C563
50 ; RTN
51 ; *********************
52 ; =SQR17
53 ; B=0 S
54 000002 19431F00 mov.w c,b ; C=B W
55 ; ?B=0 W
56 ; GOYES =SQR70
57 ; ?A=0 S
58 ; GOYES L_0C56D
59 ; L_0C563
60 ; P= 0
61 ; LC(2) #A
62 ; GOTO =INVNaN
63 ; L_0C56D
64 000003 08331F00 add.d.w b,b ; B=B+B W
65 000004 08331F00 add.d.w b,b ; B=B+B W
66 000005 08341F00 add.d.w b,c ; B=B+C W
67 000006 19420400 mov.a c,a ; C=A A
68 000007 08440400 add.d.a c,c ; C=C+C A
69 000008 19401F00 mov.w c,0 ; C=0 M
70 000009 5300000B jnc SQRT_1 ; GONC L_0C583
71 00000A 0E491F03 not.d.m c ; C=-C-1 M
72 SQRT_1: ; L_0C583
73 00000B 19420400 mov.a c,a ; C=A A
74 00000C 19241F03 mov.m a,c ; A=C W
75 00000D 08441F00 add.d.w c,c ; C=C+C W
76 00000E 08441F00 add.d.w c,c ; C=C+C W
77 00000F 08241F00 add.d.w a,c ; A=A+C W
78 000010 20000000 loadp #0 ; P= 0
79 000011 1120FFFF neq.p a,0 ; ?A#0 P
80 000012 54000014 jt SQRT_2 ; GOYES L_0C59B
81 000013 1C301F00 sr.d.w b ; BSR W
82 SQRT_2: ; L_0C59B
83 000014 1C201F00 sr.d.w a ; ASR W
84 000015 19401F00 mov.w c,0 ; C=0 W
85 000016 2000001E loadp #30 ; P= 14
86 000017 31400005 ldn c,#5 ; LC(1) #5
87 000018 1A341F00 ex.w b,c ; BCEX W
88 SQRT_3: ; L_0C5A9
89 000019 1C30FF00 sr.d.wp b ; BSR WP
90 00001A 0D31FFFF sub.d.p b,#1 ; B=B-1 P
91 SQRT_4: ; L_0C5AF
92 00001B 0931FFFF add.d.p b,#1 ; B=B+1 P
93 00001C 0C431F00 sub.d.w c,b ; C=C-B W
94 00001D 5300001B jnc SQRT_4 ; GONC L_0C5AF
95 00001E 08431F00 add.d.w c,b ; C=C+B W
96 00001F 1D401F00 sl.d.w c ; CSL W
97 000020 24000000 decp ; P=P-1
98 000021 53000019 jnc SQRT_3 ; GONC L_0C5A9
99 ; *********************
100 SQRT_5: ; =SQR70
101 ; SB=0
102 SQRT_6: ; L_0C5C6
103 000022 10401F00 eq.w c,0 ; ?C=0 W
104 000023 54000026 jt SQRT_7 ; GOYES L_0C5D1
105 000024 0D410200 sub.d.x c,#1 ; C=C-1 X
106 000025 1C400200 sr.d.x c ; CSR X
107 SQRT_7: ; L_0C5D1
108 000026 41000000 stop ; RTNCC
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Extending the precision of Woodstock or Saturn based calculators
