DeviceFS fix

As suggested in another post I’m posting these changes which will fix specialfield
string handling and the noblock special field option. If you are from rool and want a program to test the fix look in your in box.

In DeviceFS.c.Special to fix special fields not being set.

In ScanSpecial

20

                TEQ     r6, #0                                  ; end of the string yet?

                BNE     %10                                     ; no, so loop until end reached

Debug   special, “end of return tokens”, r3
30

                MOV     r4, #0                                  ; new switch, so reset result to 0

        [ {TRUE} ;COLIN_FIX_SPECIALSTRING

                LDR    r0,[sp,#CallerR0]                        ; reset to beginning of scanned string

        ]

35

In DeviceFS.c.FSystem to fix noblock

In open_input

10

                ADD     r6, r6, #1

                STR     r6, [pr, #parent_UsedInputs]            ; store a modified input counter

[ {TRUE} ;COLIN_NOBLOCK_FIX
LDR     r3, [fr, #file_Flags]
ORR     r3, r3, #ff_FileForRX :OR: ff_ModifiedCounters ; being used for RX
|
MOV     r3, #ff_FileForRX :OR: ff_ModifiedCounters ; being used for RX
]
STR     r3, [fr, #file_Flags]                   ; stash these flags
Debug   open, “file flags”, r3

in open_output

20
                ADD     r6, r6, #1
                STR     r6, [pr, #parent_UsedOutputs]           ; store a modified input counter

        [ {TRUE} ; COLIN_NOBLOCK_FIX
                LDR     r3, [fr, #file_Flags]
                ORR     r3, r3, #ff_FileForTX :OR: ff_ModifiedCounters ; being used for TX
        |
                MOV     r3, #ff_FileForTX :OR: ff_ModifiedCounters ; being used for TX
        ]
                STR     r3, [fr, #file_Flags]                   ; stash some important flags

                Debug   open, "file flags", r3

in HandleSpecial

10
                LDR     r0, sp_block                            ; maybe set the non-blocking bit
                TEQ     r0, #1
                LDR     r0, [fr, #file_Flags]
        [ {TRUE} ;COLIN_NOBLOCK_FIX
                ORREQ   r0, r0, #ff_NonBlocking
                BICNE   r0, r0, #ff_NonBlocking
        |
                ORRNE   r0, r0, #ff_NonBlocking
                BICEQ   r0, r0, #ff_NonBlocking
        ]
                STR     r0, [fr, #file_Flags]
 [ TWSleep

I can see what the last 3 patches are doing but

 LDR    r0,[sp,#CallerR0]                        ; reset to beginning of scanned string

As I read it, R5 is a copy of the start of the validation string template, this is reset into R1 for each attempted keyword match with the input string (in R0). For no match, don’t you only want to rewind the validation string, not the input string too?

R1 is changed elsewhere. It points to the start of the keyword. The keywords are stepped through and used to search for a match in the special string.

Specialstringfix.zip contains a test program for ScanSpecial which can demonstrate the affects of the change – see the readme file.

Edit: not sure if that explains it any better but basically the algorithm tries to be

i=0
foreach keyword in validation_string
{
  value[i++]=getvalue(keyword,specialstring);
  // if keyword not found value[i]=0xdeaddead
}

and specialstring is not being reset every loop

not sure if that explains it any better

Right – I see now there’s another loop further out. So for each keyword in validation_string it looked through the special field, but in the no match case never went back to the start – only ever forwards. I was concerned that by resetting R0 there was an infinite loop.

brown/Nfox/N
fox123;brown456;

would only match “brown”, and not go back to look for “fox”.

Your version of the fix you’ve put in FSystem for noblock is wrong. You changed the validation string instead of the code. The side effect of this is that now that the noblock flag is taken notice of a 0xdeaddead flag will result in nonblocking by default and existing devices will expect blocking by default.

Your version of the fix you’ve put in FSystem for noblock is wrong

The “nosleep,sleep” flag had a local precedent so it seemed sensible to follow it, given the variable names the original author chose. It looks right

                LDR     r0, sp_block            ; get the result, will be 0, 1, or DEADDEAD

                TEQ     r0, #1                  ; is it 1? ie. “block” is present

                LDR     r0, [fr, #file_Flags]

                ORRNE   r0, r0, #ff_NonBlocking ; NE → either absent or 0, that’s non-blocking

                BICEQ   r0, r0, #ff_NonBlocking ; EQ → clear the non-blocking flag, such that it blocks

                STR     r0, [fr, #file_Flags]

but I see that would not block by default. I’ll swap it round…

Darn you’ve got me in my pedantic mode now. For me the local precedence is that the first item in a switch is the same as the default. Anyway it will work thanks.