New Release! The compiler now supports the
ON statement, which allows you to GOTO/GOSUB to different lines depending on what's in a variable (1 goes to the first line number, 2 to the second and so on).
Example:
This program displays 123 and then allows the user to enter 1, 2 or 3 to get 111, 222 or 333 in response.
Code:
0 REM Enter 1 or 2 or 3 to get 111 or 222 or 333 as output
10 PRINT 123
20 INPUT X
30 ON X GOSUB 111, 222, 333
40 GOTO 10
111 PRINT 111
112 RETURN
222 PRINT 222
223 RETURN
333 PRINT 333
334 RETURN
Compiled this looks like this (It's very bloated, compiler optimizations will come later):
Code:
001 LBL 0 | 42,21, 0
002 R/S | 31
003 CF 8 | 43, 5, 8
004 RTN | 43 32
005 LBL 1 | 42,21, 1
006 CHS | 16
007 STO I | 44 25
008 LBL 2 | 42,21, 2
009 GTO I | 22 25
010 LBL 3 | 42,21, 3
011 CHS | 16
012 x<>y | 34
013 1 | 1
014 - | 30
015 TEST 0 | 43,30, 0
016 RTN | 43 32
017 R_down | 33
018 STO I | 44 25
019 R_up | 43 33
020 RTN | 43 32
021 LBL B | 42,21,12
022 1 | 1
023 2 | 2
024 3 | 3
025 GSB 0 | 32 0
026 SF 9 | 43, 4, 9
027 R/S | 31
028 CF 9 | 43, 5, 9
029 STO 0 | 44 0
030 0 | 0
031 STO I | 44 25
032 RCL 0 | 45 0
033 INT | 43 44
034 0 | 0
035 5 | 5
036 3 | 3
037 GSB 3 | 32 3
038 0 | 0
039 5 | 5
040 8 | 8
041 GSB 3 | 32 3
042 0 | 0
043 6 | 6
044 3 | 3
045 GSB 3 | 32 3
046 RCL I | 45 25
047 TEST 0 | 43,30, 0
048 GSB 2 | 32 2
049 0 | 0
050 2 | 2
051 2 | 2
052 GTO 1 | 22 1
053 1 | 1
054 1 | 1
055 1 | 1
056 GSB 0 | 32 0
057 RTN | 43 32
058 2 | 2
059 2 | 2
060 2 | 2
061 GSB 0 | 32 0
062 RTN | 43 32
063 3 | 3
064 3 | 3
065 3 | 3
066 GSB 0 | 32 0
067 RTN | 43 32
Here's the annotated version that shows how it gets compiled in more detail:
Code:
1 LBL 0
2 R/S
3 CF 8
4 RTN
5 LBL 1
6 CHS
7 STO I
8 LBL 2
9 GTO I
10 LBL 3
11 CHS
12 x<>y
13 1
14 -
15 TEST 0
16 RTN
17 R_down
18 STO I
19 R_up
20 RTN
21 LBL B
10 PRINT 123................................................22 1
23 2
24 3
25 GSB 0
20 INPUT X..................................................26 SF 9
27 R/S
28 CF 9
29 STO 0
30 ON X GOSUB 111, 222, 333.................................30 0
31 STO I
32 RCL 0
33 INT
34 0
35 5
36 3
37 GSB 3
38 0
39 5
40 8
41 GSB 3
42 0
43 6
44 3
45 GSB 3
46 RCL_I
47 TEST 0
48 GSB 2
40 GOTO 10..................................................49 0
50 2
51 2
52 GTO 1
111 PRINT 111...............................................53 1
54 1
55 1
56 GSB 0
112 RETURN..................................................57 RTN
222 PRINT 222...............................................58 2
59 2
60 2
61 GSB 0
223 RETURN..................................................62 RTN
333 PRINT 333...............................................63 3
64 3
65 3
66 GSB 0
334 RETURN..................................................67 RTN
The ON code is very tricky and I'm not sure if it's optimal. Feel free to suggest improvements!
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voyc: Compile CommodoreBASIC to HP 15-C
