Mercurial > hg > index.cgi
changeset 59:9bed204d99b9
Add RUN and GOTO; also IN XXXX for errors
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Sun, 19 Feb 2023 22:06:19 -0700 |
| parents | 24b123b3e69b |
| children | 1190f66329ab |
| files | src/lwbasic.s |
| diffstat | 1 files changed, 49 insertions(+), 6 deletions(-) [+] |
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--- a/src/lwbasic.s Sun Feb 19 16:06:07 2023 -0700 +++ b/src/lwbasic.s Sun Feb 19 22:06:19 2023 -0700 @@ -1004,6 +1004,12 @@ suba #0x20 ; shift to upper case bra writechr ; go output it ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; Write a NUL terminated string at X to the screen. Conditionally convert to upper case based on the screen type. +writestrconduc0 bsr writechrconduc ; output the character +writestrconduc lda ,x+ ; fetch character from string + bne writestrconduc0 ; brif not end of string + rts +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Fetch next input character, skip spaces. This is structured the way it is to avoid burning any register except A ; which is used for the returned value. Z will be set if the input character is NUL or a colon. C will be set if the ; input character is an ASCII digit. This allows testing Z to identify the end of a command due to either a colon or @@ -1063,10 +1069,13 @@ 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 +ERROR2 jsr writestrconduc ; output error message + ldu curline ; are we in immediate mode? + beq ERROR3 ; brif so + ldx #inmsg ; point to " in " + jsr writestrconduc ; output " in " + ldd 2,u ; get line number + jsr print_uint16d ; display the line number ERROR3 lds freetop ; reset the stack pointer (error routine could be called anywhere) ; fall through to immediate mode intentional ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; @@ -1150,6 +1159,12 @@ ; the line had been present, which could be the end of the program. D and U are clobbered. Enter at prog_findlinex to ; start searching at the line pointed to by X. Enter at prog_findline to start at the beginning of the program. Enter ; with the desired line number in binval. +prog_findlinecl ldx curline ; get current line pointer + beq prog_findline ; brif immediate mode + ldd binval ; get desired line number + cmpd 2,x ; is the desired line number >= current line? + beq prog_findline2 ; brif this is the right line (optimizes goto self) + bhi prog_findlinex ; brif desired line higher: start here instead of program start prog_findline ldx progtext ; point to start of program prog_findlinex ldu binval ; get line number to search for prog_findline0 ldd ,x ; end of program? @@ -1259,10 +1274,10 @@ bne interpret1 ; brif not clra ; clear carry to indicate normal exit rts ; return to caller -interpret1 ldd ,x++ ; are we at the end of the program? +interpret1 ldd ,x ; are we at the end of the program? beq interpret4 ; brif so - bail out stx curline ; save pointer to current line - leax 1,x ; set input pointer one before the start of the line text + leax 3,x ; set input pointer one before the start of the line text interpret2 stx inputptr interpret3 jsr nextchar ; fetch first character of next statement beq interpret ; brif end of statement - do the next statement dance @@ -1338,9 +1353,32 @@ bne cmd_data3 ; brif not - keep going bra cmd_data0 ; process stuff outside string ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; RUN command +cmd_run ;jsr closeall ; close all files + jsr curchar ; what do we have as an argument? + bcs cmd_goto ; brif a digit - it's a line number (RUN ###); do GOTO + lbne SNERROR ; brif anything else on the line - not legit command + ldx progtext ; point to start of program + bra cmd_goto0 ; go transfer control to the start of the program +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; GOTO command +cmd_goto jsr parse_lineno ; parse the line number + jsr prog_findlinecl ; go look up line number + bcc cmd_goto0 ; brif line found +ULERROR ldb #err_ul ; raise undefined line error + jmp ERROR +cmd_goto0 stx curline ; make sure we aren't flagging immediate mode + leax -1,x ; move input pointer to NUL before destination line + stx inputptr ; put input pointer there + rts ; resume interpretation at the new location +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; GOSUB command +cmd_gosub rts +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Miscelaneous strings prompt fcn 'OK' ; general prompt breakmsg fcn 'BREAK' ; "BREAK" message +inmsg fcn ' in ' ; " in " message ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Print out an unsigned 16 bit value in D to the selected output stream print_uint16d pshs d,x,y,u ; save number and make some temporaries on the stack @@ -1410,6 +1448,8 @@ fcn 'NEXT without FOR' deferr sn fcn 'Syntax error' + deferr ul + fcn 'Undefined line number' ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; The LET command which is the default if no token begins a statement cmd_let jmp SNERROR ; not yet implemented @@ -1706,6 +1746,9 @@ defcmd 'NEW',new defcmd 'PRINT',print defcmd 'LIST',list + defcmd 'RUN',run + defcmd 'GOTO',goto + defcmd 'GOSUB',gosub defcmd '-',minus,SNERROR primarydict cmdtab secondarydict functab