Mercurial > hg > index.cgi
changeset 40:68253ccbb9dc
Immediate mode line insertion, removal, and replacement
This implements a first pass untested version of handling program line
insertion and deletion in immediate mode. This comes with auxilliary
routines for parsing line numbers and fixing up the next line pointers.
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Wed, 23 Nov 2022 21:34:21 -0700 |
| parents | e956d8b6e806 |
| children | 090db8c5d509 |
| files | src/lwbasic.s |
| diffstat | 1 files changed, 106 insertions(+), 8 deletions(-) [+] |
line wrap: on
line diff
--- a/src/lwbasic.s Mon Nov 21 23:18:40 2022 -0700 +++ b/src/lwbasic.s Wed Nov 23 21:34:21 2022 -0700 @@ -194,14 +194,14 @@ ; Start of memory which has the direct page and other data. org 0 dpstart equ * ; start of direct page +zero rmb 2 ; constant zero word used for faster zeroing of 16 bit registers +binval rmb 2 ; arbitary binary value, usually a line number or integer memtop rmb 2 ; absolute top of memory in 64K memory map memsize rmb 2 ; top of memory not reserved freetop rmb 2 ; top of free memory (bottom of string space) stringtab rmb 2 ; bottom of used string space progtext rmb 2 ; pointer to start of program text -vartabint rmb 2 ; pointer to start of integer scalars -vartabfloat rmb 2 ; pointer to start of floating point scalars -vartabstring rmb 2 ; pointer to start of string scalars +vartab rmb 2 ; pointer to start of integer scalars objecttab rmb 2 ; pointer to start of arrays and other variable sized objects freestart rmb 2 ; pointer to start of unallocated memory readlinenoecho rmb 1 ; if nonzero, the readline routine won't echo its input @@ -461,9 +461,7 @@ stx progtext ; put the start of the program there clr ,x+ ; put a NULL pointer to mark end of program clr ,x+ - stx vartabint ; put start of integer variables at end of program - stx vartabfloat ; put start of floating point variables after that - stx vartabstring ; put start of string variables after that + stx vartab ; put start of integer variables at end of program stx objecttab ; also put the start of large objects there stx freestart ; mark the start of free memory lda #keyb_caps ; enable caps lock but disable all other shift states @@ -1056,8 +1054,108 @@ jsr tokenize ; tokenize the line at inputptr, return with result at tokebuff jsr interpretline ; go interpret the tokenized line bra immediate ; go handle another line -immediate1 ; handle line insert/delete/modify - bra immediate0 +immediate1 bsr parse_lineno ; parse the line number + bsr prog_findline ; go see if the line is in the program + bne immediate3 ; brif not - no need to delete it + ldu ,x ; get next line pointer which is where we start the copy from + leay ,x ; use temp pointer for copying +immediate2 lda ,u+ ; get source byte + sta ,y+ ; stash it + cmpu vartab ; did we reach the end of the program text? + blo immediate2 ; brif not + sty vartab ; save new end of program +immediate3 jsr curchar ; skip any spaces after line number + tsta ; is it the end of input (don't test for colon) + beq immediate6 ; brif so - we don't need to insert a line + pshs x ; save program insert location and line number + ldx inputptr ; point to line text + jsr tokenize ; tokenize line, get length to D + leay ,x ; save tokenized line pointer + addd #4 ; account for next line pointer and line number + ldx vartab ; get start of copy location + leau d,x ; set destination copy location D bytes further up + stu vartab ; save new end of program +immediate4 lda ,-x ; get byte from program + sta ,-u ; stash it above the empty space + cmpx ,s ; did we reach the insertion point? + bne immediate4 ; brif not - keep going + leas 2,s ; clear insertion location + stu ,x++ ; set next line pointer to not null + ldd binval ; set the line number for the program + std ,x++ +immediate5 lda ,y+ ; get byte from tokenized line + sta ,x+ ; stash it in the program + bne immediate5 ; brif not at end of tokenized line (see note for fixlineptrs) +immediate6 bsr prog_fixlineptrs ; fix up line pointers (all of them) + ldx vartab ; clear out variables + stx objecttab + stx freestart + bra immediate0 ; go handle more input +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; Fix up next line pointers. Enter at prog_fixlineptrs to do the entire program. Enter at prog_fixlineptrsx to start +; at the line pointered to by X, which MUST NOT point to the end of the program. +; +; Works by simply scanning for a NUL in the program text after a line header (pointer to next line and line number) +; and uses that as the new next line pointer. A NULL next line pointer flags the end of the program. +; +; Observation: if the program text format is changed such that it can include NULs embedded within a line, this routine +; will need to be updated to grok that. +prog_fixlineptrs + ldx progtext ; point to start of program +prog_fixlineptrsx + ldu ,x ; are we at the end of the program? + beq prog_findline2 ; brif not (borrow RTS from findline) + leau 4,x ; point to line text (past pointer and line number) +prog_fixlineptrs1 + lda ,u+ ; are we at the end of this line? + bne prog_fixlineptrs1 ; brif not + stu ,x ; set the next pointer for the previous line + leax ,u ; move to the next line + bra prog_fixlineptrsx ; go handle the next line +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; Find a line in the program. Returns with C set and Z clear if no match and C clear and Z set if a match is found. X +; will point to either the exact matched line *or* the line that would be immediately after the desired line number if +; 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_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? + beq prog_findline1 ; brif not + cmpu 2,x ; does line number match? Z set if so, clear if not; C set not found + bls prog_findline2 + ldx ,x ; move to next line + bra prog_findline0 ; see if we found the line yet +prog_findline1 coma ; set carry for not found; also clears Z because D is zero from above +prog_findline2 rts +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +; Parse a line number and return it in binval; raise syntax error if the line number overflows 16 bits unsigned. +; Preserves; registers except D. This will accept the entire 16 bit unsigned number range which is why there is +; a BCS after every shift or add. Enter with the first character in A with C set for digits and clear otherwise. +parse_lineno ldd zero ; clear out accumlator but preserve carry flag + std binval + bcc parse_lineno1 ; brif first character wasn't a digit - default to zero +parse_lineno0 suba #0x30 ; adjust to binary digit + pshs a ; save digit so we can add it later + ldd binval ; get accumulated number + lslb ; multiply accumulator by 10 + rola ; times 2 + bcs SNERROR ; brif overflow + lslb + rola ; times 4 + bcs SNERROR ; brif overflow + addd binval ; times 5 (add orignal value to times 4) + bcs SNERROR ; brif overflow + lslb + rola ; times 10 + bcs SNERROR ; brif overflow + addb ,s+ ; add in accumulated digit + adca #0 + bcs SNERROR ; brif overflow + std binval ; save accumulated number + jsr nextcharraw ; get next input character; DO NOT skip spaces + bcs parse_lineno0 ; brif it's also a digit +parse_lineno1 rts ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Main interpretation loop ;