1f4c460f4f
Add GitHub Actions CI with automated build and test. Implement real terminal I/O with raw mode (enable_raw/disable_raw, proper INKEY$ polling via VMIN=0/VTIME=0, INPUT$ function). Add Sixel graphics engine with virtual framebuffer (SCREEN 1: 320x200, SCREEN 2: 640x200), Bresenham line drawing, midpoint circle, flood fill PAINT, DRAW mini-language parser, and Sixel encoder with RLE. Replace all graphics stubs with real implementations (PSET, LINE, CIRCLE, DRAW, PAINT, COLOR, SCREEN, POINT). Fix AND/OR/XOR operator precedence to be lower than relational operators. Add 13 classic test programs (39 total). Bump version to 0.5.0.
20 lines
521 B
QBasic
20 lines
521 B
QBasic
10 REM Caesar cipher - encode and decode
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20 MG$ = "HELLO WORLD"
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30 SH% = 13
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40 GOSUB 200
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50 PRINT "Encoded: "; R$
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60 EN$ = R$
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70 MG$ = EN$ : SH% = -13
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80 GOSUB 200
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90 PRINT "Decoded: "; R$
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100 IF R$ = "HELLO WORLD" THEN PRINT "Caesar cipher OK" ELSE PRINT "FAIL"
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110 END
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200 REM Encode MG$ by SH% into R$
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210 R$ = ""
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220 FOR I = 1 TO LEN(MG$)
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230 C% = ASC(MID$(MG$, I, 1))
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240 IF C% >= 65 AND C% <= 90 THEN C% = (C% - 65 + SH% + 26) - INT((C% - 65 + SH% + 26) / 26) * 26 + 65
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250 R$ = R$ + CHR$(C%)
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260 NEXT I
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270 RETURN
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