Mercurial > hg > index.cgi
changeset 23:4b4806a32701
Add some error handling framework
Include the initial routine for handling error messages with a couple of
error messages for testing.
This includes a routine to convert to upper case if the chosen output device
doesn't support actual lower case. This is mostly intended for the VDG
screen since graphics displays, T1 VDG screens, and Coco3 screens can all
support actual lower case glyphs, as do any non-local or file devices.
This routine is mostly used for displaying error messages and other notices
the interpreter needs to display.
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Wed, 09 Nov 2022 23:07:33 -0700 |
| parents | 06417341c50e |
| children | 9586c547fcfa |
| files | src/lwbasic.s |
| diffstat | 1 files changed, 61 insertions(+), 3 deletions(-) [+] |
line wrap: on
line diff
--- a/src/lwbasic.s Wed Nov 09 18:09:19 2022 -0700 +++ b/src/lwbasic.s Wed Nov 09 23:07:33 2022 -0700 @@ -201,6 +201,7 @@ RSTVEC rmb 2 ; points to warm start routine (must start with NOP) console_curptr rmb 2 ; current cursor pointer for console driver console_blnkdel rmb 1 ; cursor blink delay +console_truelc rmb 1 ; set to nonzero if the console supports true lower case (gfx, etc.) filenum rmb 1 ; current input/output channel fileeof rmb 1 ; flag for whether last read detected EOF keyb_flags rmb 1 ; shift flags for the keyboard @@ -878,12 +879,25 @@ bne readlinee0 ; brif not bsr writechr ; echo the character readlinee0 rts +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; Write a newline if not at left margin. This will unconditinally output a newline for devices where the horizontal +; position is not knowable. +writecondnl lda filenum ; get file number + bne writenl ; brif not screen - we'll do it unconditionally + lda console_curptr+1 ; get LSB of cursor pointer + anda #0x1f ; keep only the low 5 bits (32 characters per line) + beq writecondnl0 ; brif no newline is needed + ; fallthrough intended +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; Write a newline to the chosen device. +writenl lda #0x0d ; code for carriage return - will serve as newline + ; fallthrough intended ; Write a character to the active file; all registers preserved but C will be set if the output file cannot handle ; an output character (doesn't exist, etc.) writechr tst filenum ; is it screen? beq writechr_scr ; brif writing to screen orcc #1 ; unknown device flag - rts +writecondnl0 rts ; Handle output to the screen. This is where we convert CR to CRLF writechr_scr jsr console_outchr ; output the character cmpa #0x0d ; was it CR? @@ -913,14 +927,58 @@ clrb ; clear carry to indicate not eof puls b,pc ; restore temp and return ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; Write a character to the selected output device. If the device is one that does not support actual lower case, then +; conver the character to upper case. Otherwise, pass it through as is. Currently, only the console screen falls into +; this category. This *will* modify the character in A if a change is made. +writechrconduc tst filenum ; is it screen? + bne writechr ; brif not - just output it + tst console_truelc ; does the current text screen support actual lower case? + beq writechr ; brif so - just output character + cmpa #'a ; is it lower case? + blo writechr ; brif not + cmpa #'z ; is it still lower case? + bhi writechr ; brif not + suba #0x20 ; shift to upper case + bra writechr ; go output it +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; The error handler +; +; Enter with the error number in B. This routine will do some cleanup and handle any ON ERROR GOTO handler that +; may be active. +; +; Note the error message lookup does not need to be efficient which is why the lookup just runs through the list +; of error messages in sequence looking for NUL terminators. The specific handling of B (error number) below avoids +; issues if there happen to be error codes above 128. +ERROR clr filenum ; reset display device to console + jsr writecondnl ; do a newline if needed (will preserve B) + ldx #errormsg ; point to error message list + incb ; account for decb below + bra ERROR0 ; go search for correct message +ERROR0 lda ,x+ ; end of message? + bne ERROR0 ; brif not end of message +ERROR1 decb ; at the correct one? + bne ERROR0 ; brif not - skip to next one +ERROR2 lda ,x+ ; get character to output + beq ERROR3 ; brif end of message + jsr writechrconduc ; output the character, converted to upper case situationally + bra ERROR2 ; handle another character +ERROR3 + + ; fall through to immediate mode intentional +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Immediate mode handler -prompt fcn 'OK' -immediate ldx #prompt ; point to prompt string +immediate jsr writecondnl ; do newline if required + ldx #prompt ; point to prompt string jsr console_outstrn immediate0 jsr readline ; read input line bcs immediate0 ; brif ended with BREAK ; handle line bra immediate +prompt fcn 'OK' +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; Error messages +errormsg fcn 'NEXT without FOR' ; 0 + fcn 'Syntax error' ; 1 ifndef COCO3 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Need to ensure the vectors are at 0xbff2