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added decimal mode patch

This commit is contained in:
Klaus2m5 2017-01-05 11:11:26 +01:00
parent d3fac64171
commit 1fa5bca68d
1 changed files with 61 additions and 8 deletions
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69
bugsnquirks.txt
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@ -17,35 +17,36 @@ is very limited. In a 2MHz system more than 100 interrupts per second or
interrupts requiring less than 10ms service time should be handled in machine
language. The numbers are worse if the interrupt handler gets more complex.
2. String handling when the string is in the input buffer.
When a string is entered via the input buffer (Ibuffs - Ibuffe) in Ehbasic it
is transient because it gets overwritten by the next input. In this case it
needs to be copied to the string area. In all other cases the string remains in
place and only a pointer needs to be set to the strings location.
place and only a pointer needs to be set to the string location.
There is a bug in EhBASIC to determine where the string is.
LAB_20DC
STX Sendh ; save string end high byte
LDA ssptr_h ; get string start high byte
CMP #>Ram_base ; compare with start of program memory
BCS LAB_RTST ; branch if not in utility area
STX Sendh ; save string end high byte
LDA ssptr_h ; get string start high byte
CMP #>Ram_base ; compare with start of program memory
BCS LAB_RTST ; branch if not in utility area
This does not work, if RAM_base is below the input buffer or EhBASIC itself is
below RAM_base. The fix requires the input buffer not to cross a page boundary:
LAB_20DC
STX Sendh ; save string end high byte
LDA ssptr_h ; get string start high byte
; *** begin RAM above code / Ibuff above EhBASIC Patch ***
; *** begin RAM above code / Ibuff above EhBASIC patch ***
; *** replace
; CMP #>Ram_base ; compare with start of program memory
; BCS LAB_RTST ; branch if not in utility area
; *** with
CMP #>Ibuffs ; compare with location of input buffer page
BNE LAB_RTST ; branch if not in utility area
; *** end RAM above code / Ibuff above EhBASIC Patch ***
; *** end RAM above code / Ibuff above EhBASIC patch ***
3. Output of some functions limited to integers is negative.
@ -75,3 +76,55 @@ EOR <<, >>) as they require signed integers. The value -1 is asigned to a
comparison evaluating as TRUE. Therefore logical operators must be able to
evaluate -1 correctly.
4. Use of decimal mode and invalid BCD
There is only one place in EhBASIC where decimal mode is used. HEX$() uses
invalid BCD to convert a number to a hexadecimal string. Some processors do not
support decimal mode and emulators most of the time will not support invalid
BCD (nibbles in the range of $A - $F).
LAB_AL2X
CMP #$0A ; set carry for +1 if >9
ADC #'0' ; add ASCII "0"
STA (str_pl),Y ; save to temp string
DEY ; decrement counter
RTS
A patch is available to disable use of decimal mode in EhBASIC.
LAB_AL2X
CMP #$0A ; set carry for +1 if >9
; *** begin disable decimal mode patch ***
; *** insert
BCC LAB_AL20 ; skip adjust if <= 9
ADC #$06 ; adjust for A to F
LAB_AL20
; *** end disable decimal mode patch ***
ADC #'0' ; add ASCII "0"
STA (str_pl),Y ; save to temp string
DEY ; decrement counter
RTS
At the same time you must disable SED & CLD at the HEX$() function.
LAB_HEXS
CPX #$07 ; max + 1
BCS BinFErr ; exit if too big ( > or = )
STX TempB ; save # of characters
LDA #$06 ; need 6 bytes for string
JSR LAB_MSSP ; make string space A bytes long
LDY #$05 ; set string index
; *** disable decimal mode patch - comment next line ***
; SED ; need decimal mode for nibble convert
LDA nums_3 ; get lowest byte
JSR LAB_A2HX ; convert A to ASCII hex byte and output
LDA nums_2 ; get middle byte
JSR LAB_A2HX ; convert A to ASCII hex byte and output
LDA nums_1 ; get highest byte
JSR LAB_A2HX ; convert A to ASCII hex byte and output
; *** disable decimal mode patch - comment next line ***
; CLD ; back to binary