GET$# BY is data-dependent?

[rtrussell]

This program should read 128 bytes from the file, but it only reads one byte:

   10 F$ = "TEST.$$$"
   20 F% = OPENOUT(F$)
   30 BPUT#F%, STRING$(128, CHR$(128))
   40 CLOSE #F%
   50 F% = OPENIN(F$)
   60 A$ = GET$#F% BY 128
   70 IF LEN(A$)<>128 PRINT "Failed" : STOP
   80 CLOSE #F%

This appears to be data-dependent. If line 30 is changed so that the bytes written to the file are CHR$(127) the program runs correctly.

[envenomator]

This bug is present in the Dean's port of BBC Basic v5 z80 as well

[envenomator]

This is a bug in the MOS firmware, present in all MOS firmware versions. I've created a MOS patch, tested this with BBC Basic V (z80 / ez80) and created a PR to fix it in a future MOS release (AgonPlatform/agon-mos#205)

Thanks for reporting this

[rtrussell]

This is a bug in the MOS firmware, present in all MOS firmware versions.

Bugs caused by char sometimes being signed and sometimes being unsigned, depending on the compiler and/or platform, are sadly common. I try to remember to declare variables explicitly as signed char or unsigned char. In BBC BASIC, 'byte' variables, e.g. v& or ?p%%, are always unsigned; in fact it's the only unsigned native numeric type in BBC BASIC.

[envenomator]

Keeping this open for visibility until the AgonPlatform MOS pulls my suggested fix