Difference between revisions of "DIM Basic432"
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[[Category:BASIC_Corrections]] | [[Category:BASIC_Corrections]] | ||
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Correction to the [[DIM]] statement for BASIC 4r32. | Correction to the [[DIM]] statement for BASIC 4r32. | ||
| − | [[6502_BBC_BASIC#BASIC_4.32.2C_HIBASIC_4.32|HIBASIC 4.32]] added the following check in the Multiply Upper Dimension by Lower Dimension routine: | + | [[6502_BBC_BASIC#BASIC_4.32.2C_HIBASIC_4.32|HIBASIC 4.32]] added the |
| + | following check in the Multiply Upper Dimension by Lower Dimension routine: | ||
<pre> [&95E4] BCS 11 --> &95F1 Bad Dim error</pre> | <pre> [&95E4] BCS 11 --> &95F1 Bad Dim error</pre> | ||
| − | this occurs after we have multiplied &2A-&2B by 2, and avoids memory corruption if the number of elements to dimension (&2A-&2B) is too large. | + | this occurs after we have multiplied &2A-&2B by 2, and avoids memory |
| − | This check now correctly disallows arrays to be DIMmensioned | + | corruption if the number of elements to dimension (&2A-&2B) is too large. |
| − | In BASIC IV, DIM K(1582,127) was allowed (total of 200914 elements!) which caused the following weird bug: | + | This check now correctly disallows arrays to be DIMmensioned where the |
| + | number of elements would exceed 65535 (&FFFF). In BASIC IV, DIM K(1582,127) | ||
| + | was allowed (total of 200914 elements!) which caused the following weird | ||
| + | bug: | ||
<pre> | <pre> | ||
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</pre> | </pre> | ||
| − | Memory was corrupted, causing BASIC to become confused. In BASIC4 r32, DIM K(1582,127) now produces 'Bad DIM' error. | + | Memory was corrupted, causing BASIC to become confused. In BASIC4 r32, DIM |
| + | K(1582,127) now correctly produces 'Bad DIM' error. | ||
Latest revision as of 12:47, 17 October 2020
Correction to the DIM statement for BASIC 4r32.
HIBASIC 4.32 added the following check in the Multiply Upper Dimension by Lower Dimension routine:
[&95E4] BCS 11 --> &95F1 Bad Dim error
this occurs after we have multiplied &2A-&2B by 2, and avoids memory corruption if the number of elements to dimension (&2A-&2B) is too large. This check now correctly disallows arrays to be DIMmensioned where the number of elements would exceed 65535 (&FFFF). In BASIC IV, DIM K(1582,127) was allowed (total of 200914 elements!) which caused the following weird bug:
>L. 10 DIM K(1582,127) 20 FOR I% =1 TO 1582 30 FOR J%=1 TO 127 40 K(I%,J%)=56.77777 50 NEXT J% 60 NEXT I% >RUN Array at line 40 >L. 0 DIM K(1582,127) 0 FOR I% =1 TO 1582 0 FOR J%=1 TO 127 0 K(I%,J%)=56.77777 0 NEXT J% 0 NEXT I% >
Memory was corrupted, causing BASIC to become confused. In BASIC4 r32, DIM K(1582,127) now correctly produces 'Bad DIM' error.
