6502/6502_EhBASIC_V2.22
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fixed minor INPUT & CONT bugs

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fixed can't continue error on 1st statement after direct mode
fixed syntax error after "Redo from start" when INPUT is the first run
mode statement
changed INPUT to throw "break in line ##" on empty line input
This commit is contained in:
Klaus2m5 2017-12-10 13:26:08 +01:00
parent 1dd25eb8a3
commit 229c744455
2 changed files with 33 additions and 11 deletions
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16
bugsnquirks.txt
View File

@ -175,3 +175,19 @@ We need to replace it like below:
Ibuffs = VEC_SV+$16
; start of input buffer after IRQ/NMI code
Ibuffe = Ibuffs+$47; end of input buffer
6. First statement after direct mode does not set the continue pointer
After a RUN or GOTO in direct mode CONT does not work for the first statement in
run mode. It throws a "Can't continue error". If that first statement is INPUT
then "Redo from start" causes a subsequent syntax error.
It is actually a hen and egg problem as the continue pointer (Cpntrh/l) is saved
during the inner loop if not in direct mode, but direct mode (Clineh = $FF) is
only cleared later in the same loop.
The fix is in the patched folder (version 2.22p2). The continue counter is now
always saved and the decission to continue is postponed until the CONT statement
is executed and based on the fact that the continue pointer must not point to
the input buffer in run mode.

28
patched/basic.asm
View File

@ -1,5 +1,5 @@
; Enhanced BASIC to assemble under 6502 simulator, $ver 2.22p
; Enhanced BASIC to assemble under 6502 simulator, $ver 2.22p2
; $E7E1 $E7CF $E7C6 $E7D3 $E7D1 $E7D5 $E7CF $E81E $E825
@ -20,6 +20,8 @@
; 2.22p patched to disable use of decimal mode and fix Ibuff issues
; (bugsnquirks.txt notes 2, 4 and 5)
; tabs converted to spaces, tabwidth=6
; 2.22p2 fixed can't continue error on 1st statement after direct mode
; changed INPUT to throw "break in line ##" on empty line input
; zero page use ..
@ -1286,7 +1288,8 @@ LAB_1491
LDX #$FD ; new stack pointer
TXS ; reset stack
LDA #$00 ; clear byte
STA Cpntrh ; clear continue pointer high byte
;*** fix p2: no longer necessary as the continue pointer is saved anyway
; STA Cpntrh ; clear continue pointer high byte
STA Sufnxf ; clear subscript/FNX flag
LAB_14A6
RTS
@ -1518,7 +1521,8 @@ LAB_15C2
LDX Clineh ; continue line is $FFxx for immediate mode
; ($00xx for RUN from immediate mode)
INX ; increment it (now $00 if immediate mode)
BEQ LAB_15D1 ; branch if null (immediate mode)
;*** fix p2: skip no longer necessary as the continue pointer is saved anyway
; BEQ LAB_15D1 ; branch if null (immediate mode)
STA Cpntrl ; save continue pointer low byte
STY Cpntrh ; save continue pointer high byte
@ -1609,12 +1613,12 @@ LAB_163B
BNE LAB_167A ; if wasn't CTRL-C or there is a following byte return
LDA Bpntrh ; get the BASIC execute pointer high byte
EOR #>Ibuffs ; compare with buffer address high byte (Cb unchanged)
BEQ LAB_164F ; branch if the BASIC pointer is in the input buffer
; (can't continue in immediate mode)
; else ..
EOR #>Ibuffs ; correct the bits
;*** fix p2: skip no longer necessary as the continue pointer is saved anyway
; EOR #>Ibuffs ; compare with buffer address high byte (Cb unchanged)
; BEQ LAB_164F ; branch if the BASIC pointer is in the input buffer
; ; (can't continue in immediate mode)
; ; else ..
; EOR #>Ibuffs ; correct the bits
LDY Bpntrl ; get BASIC execute pointer low byte
STY Cpntrl ; save continue pointer low byte
STA Cpntrh ; save continue pointer high byte
@ -1713,6 +1717,7 @@ LAB_CONT
BNE LAB_167A ; if following byte exit to do syntax error
LDY Cpntrh ; get continue pointer high byte
CPY #>Ibuffs ; *** fix p2: test direct mode
BNE LAB_166C ; go do continue if we can
LDX #$1E ; error code $1E ("Can't continue" error)
@ -2591,7 +2596,8 @@ LAB_1934
CMP Ibuffs ; test first byte in buffer
BNE LAB_1953 ; branch if not null input
CLC ; was null input so clear carry to exit program
; *** change p2: keep carry set to throw break message
; CLC ; was null input so clear carry to exit program
JMP LAB_1647 ; go do BREAK exit
; perform READ
@ -7832,7 +7838,7 @@ LAB_MSZM
LAB_SMSG
.byte " Bytes free",$0D,$0A,$0A
.byte "Enhanced BASIC 2.22p",$0A,$00
.byte "Enhanced BASIC 2.22p2",$0A,$00
; numeric constants and series