eb32021c19
Replaces individual malloc/free string management with a contiguous pool
(default 32KB) and compacting GC, matching the original GW-BASIC's
GETSPA/GARBAG architecture. Allocation is a bump pointer; gw_str_free()
is a no-op (descriptors are nulled, data reclaimed by GC). Compaction
runs at statement boundaries when the pool drops below 4KB free, walking
the variable table and array storage to relocate live strings.
FRE() now returns actual free pool space. FRE("") triggers a GC pass
before reporting. CLEAR n sets the string space size.
32 lines
1000 B
QBasic
32 lines
1000 B
QBasic
10 REM Test string garbage collection
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20 REM FRE("") triggers GC and returns free string space
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30 F0 = FRE("")
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40 IF F0 > 0 THEN PRINT "INITIAL OK" ELSE PRINT "INITIAL FAIL"
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50 REM --- Allocate some string variables
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60 A$ = STRING$(200, "A")
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70 B$ = STRING$(200, "B")
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80 C$ = STRING$(200, "C")
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90 F1 = FRE("")
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100 IF F1 < F0 THEN PRINT "ALLOC OK" ELSE PRINT "ALLOC FAIL"
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110 REM --- Overwrite with shorter strings (old data becomes garbage)
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120 A$ = "short"
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130 B$ = "tiny"
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140 C$ = "x"
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150 F2 = FRE("")
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160 IF F2 > F1 THEN PRINT "GC RECLAIMED" ELSE PRINT "GC FAIL"
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170 REM --- Stress test: loop with string concatenation
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180 CLEAR 4096
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190 D$ = ""
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200 FOR I = 1 TO 50
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210 D$ = D$ + "X"
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220 NEXT I
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230 PRINT "CONCAT LEN="; LEN(D$)
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240 F3 = FRE("")
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250 IF F3 > 0 THEN PRINT "POOL OK" ELSE PRINT "POOL FAIL"
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260 REM --- CLEAR with string space size
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270 CLEAR 8192
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280 F4 = FRE("")
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290 IF F4 > 7000 AND F4 < 9000 THEN PRINT "CLEAR SIZE OK" ELSE PRINT "CLEAR SIZE FAIL"
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300 PRINT "ALL DONE"
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310 SYSTEM
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