1459 lines
52 KiB
Plaintext
1459 lines
52 KiB
Plaintext
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{-----------------------------------------------------------------------+
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| Recreation of Tiny BASIC for Gigatron TTL microcomputer |
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| - Integer BASIC, with PRINT supporting string constants |
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| - Supports roughly 300 line programs in the 32K system |
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| - Multiple statements per line, up to 25 characters combined |
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| - Based on Dennis Allison's original 1976 Tiny BASIC |
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| - Extended with POKE/PEEK/RND/FOR/NEXT/CLS/AT/PUT/MODE/Arrays/ |
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| LINE/SAVE |
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+-----------------------------------------------------------------------}
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gcl0x
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{
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History:
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2018-06-19 (marcelk) Scaffolding: can evaluate direct print statements
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2018-06-21 (marcelk) Can edit programs, delete lines, but no RUN yet
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2018-06-23 (marcelk) Can RUN, GOTO, GOSUB, RETURN and break program
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2018-06-24 (marcelk) Can do IF/THEN, INPUT and END: feature complete
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2018-06-25 (marcelk) LIST shows free bytes; Trailing (semi-)colon in PRINT;
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LET is now optional; PEEK/POKE; Better INPUT;
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NEW clears variables; Aliases for PRINT and REM
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2018-07-03 (marcelk) Add RND(), with 0 <= RND(n) < |n|; USR()
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2018-07-18 (marcelk) Fix GOSUB/RETURN parsing bug causing syntax error
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2018-07-22 (marcelk) Add PUT, FOR/NEXT, ':', MODE (ROMv2), AT, CLS, arrays
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2018-08-14 (marcelk) SAVE, LINE (both draft)
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2018-08-22 (marcelk) LINE now wraps around edges to stay on screen
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2018-08-31 (marcelk) SAVE into BabelFish EEPROM
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2018-09-04 (marcelk) Faster start; Error when SAVE not there; Tiny BASIC v2
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2019-07-06 (marcelk) Update GCL notation (no changes to GT1 file)
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2019-07-07 (marcelk) PrintChar accepts arrow chars; Fix indent issue #40
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2019-07-08 (marcelk) Reenable video on input after MODE 1975; Tiny BASIC v3
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2019-12-14 (marcelk) Accept hexadecimal numbers $....; Tiny BASIC DEV
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Formal grammar:
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Line ::= Number Statements | Statements
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Statements ::= Statement (':' Statement)*
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Statement ::= ('PRINT'|'?') ((String|Expression) [,;])*
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(String|Expression)?
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| 'AT' Expression (',' Expression)?
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| 'PUT' Expression
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| 'CLS'
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| 'LINE' Expression ',' Expression
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| 'IF' Expression RelOp Expression 'THEN'? Statements
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| 'GOTO' Expression
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| 'INPUT' Variable (',' Variable)*
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| 'LET'? Variable ('(' Expression ')')? '=' Expression
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| 'FOR' Variable '=' Expression 'TO' Expression
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| 'NEXT' Variable
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| 'POKE' Expression ',' Expression
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| 'GOSUB' Expression
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| 'RETURN'
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| ('REM'|"'") Character*
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| 'MODE' Expression
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| 'NEW'
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| 'LIST'
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| 'RUN'
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| 'END'
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| 'SAVE'
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Expression ::= [+-]? Term ([+-] Term)*
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Term ::= Factor ([*/%] Factor)*
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Factor ::= Variable | Number | Hexnum
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| (Variable|'PEEK'|'RND'|'USR')? '(' Expression ')'
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RelOp ::= '=' | '<' | '>' | '<=' | '>=' | '<>'
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Number ::= [0-9]+
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Hexnum ::= $[0-9A-F]+
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Variable ::= [A-Z] | '@'
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String ::= '"' ([#x20-#x21] | [#x23-#x7E])* '"'
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Character ::= [#x20-#x7E]
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Recommended filename extension:
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.gtb GigaTron BASIC / Gigatron Tiny BASIC
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Error messages:
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Break error Program (or LIST command) interrupted /
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Out of space for SAVE (510 bytes for ATTiny85!)
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Syntax error Parse error / Program too large for memory (~300 lines)
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Value error Value or index out of range / Calculation error
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(division by 0) / NEXT without FOR / Wrong ROM version
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Stack error GOSUB nesting too deep / RETURN without GOSUB
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Line error Line number not found / RUN empty program
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Memory allocation:
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$30 - $7f BASIC interpreter variables
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$81 - $ff Stack for BASIC and vCPU (>50 GOSUB levels)
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$200 - $19ff BASIC interpreter, partly next to screen memory
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$1ba0 - $1bbf Input buffer ('line 0')
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$1bc0 - Programs stored in the invisible part of screen memory
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- $7ebf Arrays at the end, growing down
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$7ec0 - $7eff FOR-NEXT loop pointers
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$7fa0 - $7fbf SAVE buffer
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$7fc0 - $7fff BASIC variables A..Z
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$8000 - $ffff Optional extra memory for BASIC programs (64K extension)
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(Variables etcetera move to the last two pages)
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Undocumented features and/or bugs:
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PRINT vs. print Keywords and variable names are case-insensitive
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PRINT 6/-2 Syntax error (original Tiny BASIC quirk, to be solved)
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PRINT a;b Concatenates output without separation
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IF statement There is no syntax check for trailing garbage
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RETURN There is no syntax check for trailing garbage
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>< For 'not equal' is not implemented. Use just <>
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<>= Also works as (useless) operator in condition of IF
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No 'GO TO' Must be typed as 'GOTO'. Also 'GOSUB', not 'GO SUB'
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INPUT Accepts full expressions as input, including variables!
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INPUT Can give syntax error in direct mode (buffer conflict)
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Break error Gives the line it was about to start: resume with GOTO
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PRINT "xxx An unterminated string is silently accepted
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60000 vs. 90000 Many (too) large constants give an error, but not all!
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A(256) Many (too) large idexes give an error, but not all!
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Lowercase @ The backquote ('`') is recognized as alias for '@'
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FOR-NEXT Doesn't work over 16-bit ranges (FOR i=-30000 TO 30000)
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References:
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https://en.wikipedia.org/wiki/Tiny_BASIC
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Wikipedia article
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http://www.ittybittycomputers.com/IttyBitty/TinyBasic/DDJ1/Design.html
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DESIGN NOTES FOR TINY BASIC (Dennis Allison et al.)
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http://www.ittybittycomputers.com/IttyBitty/TinyBasic/
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Tom Pittman's implementation
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http://p112.sourceforge.net/tbp112.html
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P112 Tiny Basic User's Guide (V1.0, 18 FEB 1999)
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http://www.bitsavers.org/pdf/interfaceAge/197612/092-108.pdf
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Dr. Wang's Palo Alto Tiny Basic (Roger Rauskolb)
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https://www.applefritter.com/node/2859
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Apple 1 BASIC
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'Maybe in vN+1' list:
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A(0)=x,y,z Array assignment with list expression
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A$ .. Z$ String variables (only in LET, PRINT, INPUT?)
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Boot Some kind of autorun of a saved program
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Speed Cache result of the statement detection (checkpointing)
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Speed Alternative: LET detection is now last, but should be first
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IF Reintroduce the missing syntax error check
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A="... As poor-men's substitute for DATA/READ?
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@ Give it an implicit meaning such as "max index in arrays"?
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Speed Cache result of NextBlock (at offset 30 of block?)
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'Maybe in vN+2' list:
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Unary minus Original Tiny BASIC does it wrong in some edge cases: 8/-2
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Speed Cache GOTO/GOSUB target (only for constant targets...)
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Speed SYS functions for NextBlock, EndOfLine, Number
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TUNE/PLAY Play a note/score
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ABS(/SGN( Built-in function
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A$() Indexing in string variable, gives integer (handle in Factor)
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Speed Move stack check from Expression to Factor (and GOSUB)
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LEN()/A$()= More string stuff
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'Probably not soon' list:
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NEXT Without variable (complicates 'Variable' subroutine)
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A0 .. Z9 Much more variable space (as in Apple-1 basic)
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ROM peek rpeek()? Some predefined USR functions?
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A$(i,j) Substrings (only in PRINT)
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LOAD From where? EPROM? "Cassette interface".
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DIM A() And bound checks...
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TI/TI$ Built-in variable for time? (only in MS BASICs). Setting also?
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TAB() As in Apple-1 BASIC (Weird: TAB(N) advances to N-1...)
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SPC() Spaces
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Speed Binary search for GotoValue -> Only speeds up large programs
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"" or """ For printing the quote character itself (use: PUT 34)
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Overflow Errors on overflow for + - and *
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WAIT/PAUSE -> Make a loop subroutine
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LIST <n> List one line
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a-z A-Z As different variables
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>< For unequal
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CLEAR For NEW ('CLEAR' is original TinyBASIC syntax, but who cares..)
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READ, DATA Possibly put in unused lines? (RESTORE)
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AND OR NOT At least in IF statements
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ELSE Will slow down IF, because it has to scan for this
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DEF FNx
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Memory layout:
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a0 b0 c0 d0 e0 f0 ff
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+-----------------------+-----------------------+-----------------------+
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$1ba0 | Input buffer Begin->| Program line 10 | Program line 20 |
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+-----------------------+-----------------------+-----------------------+
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$1ca0 | Program line 30 | Program line 40 | Program line 45 |
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+-----------------------+-----------------------+-----------------------+
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$1da0 | Program line 50 | Program line 60 End->|K(96) Z(96)|
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+-----------------------+-----------------------+-----------------------+
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| | @(95) J(95)|K(95) Z(95)|
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: : : :
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: : : :
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: : : :
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| | @(1) J(1)|K(1) Z(1)|
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+-----------------------+-----------------------+-----------------------+
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$7da0 | | @(0) J(0)|K(0) Z(0)|
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+-----------------------+-----------------------+-----------------------+
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$7ea0 | | For loops @ A B ... J | K ... S T U V W X Y Z |
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+-----------------------+-----------------------+-----------------------+
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$7fa0 | SAVE buffer | Variables @ A B ... J | K ... S T U V W X Y Z |
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+-----------------------+-----------------------+-----------------------+
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Totally random ideas:
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Alternative byte allocation in block:
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0 Checkpoint offset (set by Insert to 5)
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1-2 Checkpoint address (set by Insert to Statement)
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3-4 Line number
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5-29 Text (without line number) and terminating zero
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30-31 Next block address? Goto address?
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Some concepts to fake strings
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Variable = String
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PRINT Variable '$'
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Variable '$' '=' (Variable '$' | String)
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PRINT Variable '$'
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But how about INPUT A$?
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Ideas for demo programs:
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Rainbow Show palette in a nice way
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Clock
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Maze The famous one-liner with / and \ -> Easter egg in ROMv2
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Circles Lots of math
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Music Play tones, vary with waveforms
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Sprites Fake sprites with printing chars at arbitrary positions
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}
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{-----------------------------------------------------------------------+
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| RAM page 2 |
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+-----------------------------------------------------------------------}
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$01df deek Pos= {Bottom character row in screen memory}
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{Slightly cheating with endianness}
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{ Process an expression factor, result in Value }
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[def
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push
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Number! {Test for decimal constant}
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[if>=0
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Spaces!
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pop ret] {Result already in Value}
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Active, $24^ [if=0 {Test for hexadecimal constant $....}
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&_Hexnum call
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Spaces!
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pop ret]
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Keyword! `( #0
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[if<>0
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Expression!
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else
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Keyword! `peek( #0
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[if<>0
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Expression!
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peek Value=
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else
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Keyword! `rnd( #0
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[if<>0
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Expression!
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\SYS_Random_34 _sysFn= {Prepare SYS call}
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[do 34!! if<0loop] {Get positive random number}
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Divide! {Modulo expression}
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i Value=
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else
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Keyword! `usr( #0
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[if<>0
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Expression!
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Value! Value= {vCPU call and result}
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else
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Variable! k= {Otherwise it MUST be a variable}
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Spaces!
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Keyword! `( #0
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[if<>0 {Optional array index}
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push k %0= {Save address on stack}
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Expression!
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[if<0 ValueError!] {Index must be non-negative}
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%0 k= pop {Pop address from stack}
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>k, Value- 2- >k.
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End k^ {64K safe bound check}
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[if<0 End {Opposite signs}
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else k End-] {Equal signs}
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[if<0 ValueError!]
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Keyword! `) #0
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if=0 SyntaxError!]
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k; Value= {Fetch value}
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pop ret
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]]]]
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Keyword! `) #0
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[if=0 SyntaxError!]
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pop ret
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] Factor=
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{ Print inline string. Returns 0 }
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[def
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\vLR; tmp= {vLR points to inline argument}
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[do
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tmp, <tmp++ {Grab next character}
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if<>0 PrintChar! {Print as long as non-zero}
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loop]
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tmp! {Returns to caller}
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] PrintS=
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[def
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\serialRaw, 3^ {Test for Ctrl-C (ASCII ETX) as break request}
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[if=0
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PrintCharScreen PrintChar= {In case we break a SAVE command}
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Prompt! `Break #0]
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ret
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] TestBreak=
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{-----------------------------------------------------------------------+
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|} >\vLR++ ret { RAM page 3 |
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+-----------------------------------------------------------------------}
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*=$0300
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{ Print ASCII character (32..131) on screen in 5x8 pixels }
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{ For valid characters, return the actual position }
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[def
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k= {Temporarily save character}
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[131- if<=0 {Suppress characters >131}
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>Pos, 120- if<=0 {Suppress when vertically protruding
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screen memory (note this can be in the
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middle of the screen after scrolling
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and using AT with non-multiples of 8,
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leading to unexpected missing of text}
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<Pos, 154- [if>0 {Automatic newline BEFORE printing}
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push Newline! pop]
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k 82- {Map ASCII code to offset in font table}
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[if<0 50+ i= \font32up {ASCII 32..81}
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else i= \font82up] {ASCII 82..127}
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k=
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i if>=0 {Suppress characters <32}
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2<< i+ {Multiply by 5}
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k+ k= {Add to page address to reach bitmap data}
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\SYS_VDrawBits_134 {Prepare SYS calls}
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_sysFn=
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_sysArgs6 _sysArgs0= {Apply caller-defined colors}
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Pos \sysArgs4: {Position for character}
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%-2= {Temporarily park return value on the stack}
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6+ Pos= {Advance position by 6 pixels}
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5 [do i= {Draw 5 vertical slices}
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k 0?? \sysArgs2. {Get slice from ROM}
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134!! {Invoke SYS function to draw pixels}
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<k++ <\sysArgs4++ {Advance to next slice}
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i 1- if>0loop] {Looping}
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\sysArgs2. 134!! {Render 6th slice}
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%-2] {Return effective position}
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ret
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] PrintChar=
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PrintCharScreen=
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{ Accept ASCII characters from console input with line editting }
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[def
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push
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tmp= {Line number}
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{ On ROM v4 and higher `MODE 1975' disables all video/audio/IO/etc }
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{ completely. Better reactivate it before waiting for new input. }
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\SYS_SetMode_v2_80 _sysFn=
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\romType, \romTypeValue_ROMv4-
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[if>=0 255- 80!!] {Any value <0 will restore signal, except -177.}
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{But -177+255+$38 isn't valid romType content,}
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{so that's just fine.}
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&_Buffer Active= {Input buffer}
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tmp Active: {For error messages}
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$a2 <Active. {Text area}
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[do {NEXTCHAR}
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127 PrintChar! Pos= {Draw cursor symbol}
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\serialRaw, [do {Wait for key change}
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tmp= {Remember previous value}
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\serialRaw, Active. {Read new input value}
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tmp^ if=0 {If no change}
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Active, loop] {Keep waiting}
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Active, 10^ if<>0 {Enter/return breaks NEXTCHAR loop}
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117^ [if=0 {Delete pressed (10^127 == 117)}
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$20 PrintChar! Pos= {Remove cursor}
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<Pos, 6- [if>=0 {If not on first position}
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<Pos. {Step back}
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Active 1- Active=] {Remove character from buffer}
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loop] {To NEXTCHAR}
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96- if>=0loop {Ignore apparent unprintable garbage}
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<Pos, 150- [if>=0 {Fewer than 2 chars or 11 pixels will fit}
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$a2 <Active. {Discard of too long input}
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$5c PrintChar! {Overflow indicator '\'}
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loop] {To NEXTCHAR, cursor will print on new line}
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Active, PrintChar! {Print accepted characters}
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<Active++ {Advance pointer, keeping the character}
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loop] {To NEXTCHAR}
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&_GetLine2 call {Part2}
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]
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{-----------------------------------------------------------------------+
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|} >\vLR++ ret { RAM page 4 |
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+-----------------------------------------------------------------------}
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*=$0400
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GetLine=
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{ Statement executor. Doesn't return through vLR }
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{ Active must point to text or terminating zero, NOT to the line number }
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[def
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Spaces!
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Keyword! `goto #0
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[if<>0
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Expression! {Computed goto}
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GotoValue!] {Find that line and continue there}
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Keyword! `gosub #0
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[if<>0
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Expression! {Also does the stack check}
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push Active %0= {Push current line to stack}
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GotoValue!] {Find that line and continue there}
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Keyword! `return #0
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[if<>0
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\vSP, [if=0 StackError!] {Top of stack}
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deek Active= pop {Pop line from stack}
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EndOfLine!]
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Keyword! `if #0
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[if<>0
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Expression!
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4-- %2= {Push first value on stack}
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RelOp!
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[if=0 SyntaxError!]
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%0= {Park RelOp bits on stack}
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Expression!
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Keyword! `then #0 {Optional}
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%2 Value^ {Do the comparison, beware of overflows}
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[if<0 %2 {Opposite signs}
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else %2 Value-] {Same signs}
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[if>0 4] {First is greater}
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[if<0 1] {Second is greater}
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[if=0 2] {Values are equal}
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i= %0 i& {Compare to RelOp bits}
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4++ {Restore stack}
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[if<>0 Statements!] {Conditional execution}
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[do
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Active, if<>0 {Find end of line}
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<Active++ loop]
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EndOfLine!] {Continue with next line}
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Keyword! `poke #0
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[if<>0
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Expression!
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Address=
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Keyword! `, #0
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[if=0 SyntaxError!]
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Expression!
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Address. {Write byte to memory}
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EndOfLine!]
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Keyword! `' #0
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[if=0 Keyword! `rem #0]
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[if<>0
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[do
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Active, if<>0 {Find end of line}
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<Active++ loop]
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EndOfLine!]
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Keyword! `line #0
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[if<>0 &_Line call]
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Keyword! `end #0
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[if<>0 Prompt! #0]
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&_Statements2 call {Continue in another page}
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] Statements=
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|
>\vLR++ >\vLR++ ret {Hop over next page}
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 5 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$0500
|
|
|
|
_Statements2=*
|
|
|
|
{ Continuation of Statement }
|
|
|
|
Keyword! `next #0
|
|
[if<>0
|
|
Variable! Address= {Pointer to loop variable}
|
|
push Active %0= {Park program index on stack}
|
|
-$100 Address+ deek {Retrieve loop pointer}
|
|
[if=0 ValueError!] {NEXT without FOR error}
|
|
Active= {Switch back to tail of FOR statement}
|
|
Expression! {Evaluate end value}
|
|
Address; 1+ Address: {Increment loop variable}
|
|
Value- {Compare with end value}
|
|
{ Value^ {XXX 16-bit safe comparison}
|
|
[if<0 Value^ {Opposite signs}
|
|
else Value^ Value-] } {Same signs}
|
|
[if>0 {Loop variable > End value}
|
|
%0 Active= {Break the loop}
|
|
Spaces!]
|
|
pop {Shorter than 2++}
|
|
TestBreak! {Test for break request}
|
|
EndOfLine!]
|
|
|
|
Keyword! `for #0
|
|
[if<>0
|
|
Variable! Address= {Pointer to loop variable}
|
|
Spaces!
|
|
Keyword! `= #0
|
|
[if=0 SyntaxError!]
|
|
Expression! {Evaluate expression}
|
|
Address: {Store value in variable}
|
|
Keyword! `to #0
|
|
[if=0 SyntaxError!]
|
|
-$100 Address+ j= {Retrieve loop pointer}
|
|
Active j: {Remember return point for NEXT}
|
|
Expression! {Evaluate but ignore result}
|
|
EndOfLine!]
|
|
|
|
Keyword! `at #0
|
|
[if<>0
|
|
Expression! {X position}
|
|
[if<0 ValueError!]
|
|
<Pos.
|
|
Keyword! `, #0
|
|
[if<>0
|
|
Expression! {Optional Y position}
|
|
[if<0 ValueError!]
|
|
120-
|
|
[if>=0 ValueError!] {Point into videoTable}
|
|
248+ 1<< {\videoTable+2*y}
|
|
peek >Pos.]
|
|
EndOfLine!]
|
|
|
|
Keyword! `put #0
|
|
[if<>0
|
|
Expression!
|
|
PrintChar!
|
|
EndOfLine!]
|
|
|
|
Keyword! `mode #0
|
|
[if<>0
|
|
Expression! {Degrade gracefully in ROM v1}
|
|
\romType,
|
|
\romTypeValue_ROMv2-
|
|
[if>=0
|
|
\SYS_SetMode_v2_80 {Available from ROM v2}
|
|
_sysFn= Value 80!!]
|
|
EndOfLine!]
|
|
|
|
&_Statements3 call
|
|
|
|
_Hexnum=*
|
|
0 [do
|
|
Value= {Update partial result}
|
|
4<< i= {Multiply by 16 before adding hex digit}
|
|
<Active++ Active, {Grab next character}
|
|
$30- {'0'} if>=0 {Bail out if out of range}
|
|
10- {'9'} [if<0 {Decimal digit}
|
|
10+ {Map in 0..9 range}
|
|
i+ loop] {Add it to value}
|
|
$df& {Ignore case}
|
|
7- {'A'} if>=0 {Skip :;<=>?@ and Z[\]^_`}
|
|
6- {'F'} [if<0 {A..F or a..f}
|
|
16+ {Map in 10..15 range}
|
|
i+ loop] {Add it to value}
|
|
] {Silently accepts bare $ as 0}
|
|
ret
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 6 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$0600
|
|
|
|
{
|
|
Six scenarios for InsertLine Check Search Shift Copy Shift
|
|
memory line down buffer up
|
|
1. Append a new line > last X - - X -
|
|
2. True insert of a new line < last X X X X -
|
|
3. Overwrite of existing line <= last - X - X -
|
|
4. Delete of existing line <= last - X - - X
|
|
5. Delete of non-existing line < last X(!) X X(!) - X(!)
|
|
6. Delete of non-existing line > last - - - - -
|
|
}
|
|
{ Handle commands that start with a line number }
|
|
[def
|
|
push
|
|
Number!
|
|
[if>0
|
|
{ Lookup line number in program }
|
|
End i= j= {Setup i and j for below}
|
|
Begin^ [if<>0 {Last line number is zero when no program}
|
|
End PrevBlock! deek] {Or read it from the last block}
|
|
Value- {Compare to given number}
|
|
[if>=0 {If insert/modify instead of append}
|
|
Begin [do i= {Loop over program from beginning}
|
|
i; Value- if<0 {Stop if found or past it}
|
|
i NextBlock! loop] {Advance to next line}
|
|
if>0 {Insert scenario}
|
|
0; End^ {Compare against top of memory}
|
|
[if<>0 {Do the copy only when safe (give error later)}
|
|
[do {Copy rest of program one one slot up}
|
|
j k= PrevBlock! {Go up one block}
|
|
j= tmp=
|
|
[do {Copy tmp[0:31] to k[0:31]}
|
|
tmp, k. {Copy as bytes, don't bother with word copy}
|
|
<tmp++ <k++ {Advance both pointers}
|
|
tmp 31&
|
|
if<>0loop] {Copy all 32 bytes}
|
|
|
|
j i^ if<>0loop]
|
|
]
|
|
1 {Non-zero to trigger advancing of End below}
|
|
]
|
|
{ Expand program space if needed }
|
|
[if<>0
|
|
0; $80- $c0- {Correct for variables}
|
|
End^ {Compare End against top of memory}
|
|
[if=0 SyntaxError!] {Out of memory error if equal}
|
|
End NextBlock! End=] {Otherwise grab space for new line}
|
|
|
|
Active, {Inspect if line has any content}
|
|
[if<>0
|
|
{ Copy line from buffer into program }
|
|
Value i: {Copy line number}
|
|
<i++ {Copy line text}
|
|
[do
|
|
<i++
|
|
Active, <Active++ {From input buffer}
|
|
i. {Into program memory}
|
|
if<>0loop] {Until terminating zero}
|
|
else
|
|
{ Bare line number means delete that line }
|
|
i j= {i still points at line to be deleted}
|
|
[do
|
|
End^ if<>0 {Until end of program}
|
|
j NextBlock! j= tmp= {Go down one block}
|
|
[do {Copy tmp[0:31] to i[0:31]}
|
|
tmp, i. {Copy as bytes, don't bother with word copy}
|
|
<tmp++ <i++ {Advance both pointers}
|
|
tmp 31& if<>0loop] {Copy all 32 bytes}
|
|
j i=
|
|
loop]
|
|
End PrevBlock! End= {Remove last line from program}
|
|
]
|
|
Value {Report line number to caller}
|
|
]
|
|
pop ret
|
|
] Insert=
|
|
|
|
$353f \sysArgs6: {Pen color blue/purple, background color white}
|
|
|
|
{ Note: It is safe here to call functions before hopping over to page 8 }
|
|
|
|
&_Newline Newline= call {Scroll and clear last line}
|
|
|
|
{ Welcome message }
|
|
PrintS! `***`Tiny`BASIC`DEV #0
|
|
Newline!
|
|
|
|
{ Hop to next page }
|
|
$08a0 _vLR= ret
|
|
|
|
_GetLine2=*
|
|
|
|
{ Continuation of GetLine }
|
|
|
|
0 Active. {Terminate input with zero}
|
|
$20 PrintChar! {Remove cursor}
|
|
Newline!
|
|
$a2 <Active. {Back to start of buffer}
|
|
Spaces! {Process leading spaces}
|
|
Active, {Tell caller if there is input}
|
|
pop ret
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 8 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$08a0
|
|
|
|
{ Calculate address of next 32-byte block for storing BASIC lines }
|
|
{ Realign if needed }
|
|
[def
|
|
31| 1+ tmp= {Advance to next 32-byte memory block}
|
|
[if>0 {In the first 32K...}
|
|
$e0& if=0 {...wrap around visible screen memory}
|
|
tmp 160+ ret]
|
|
tmp
|
|
ret
|
|
] NextBlock=
|
|
|
|
{ Go to previous block. Assume vAC already aligned to valid 32-byte block }
|
|
[def
|
|
32- tmp= {Move back to previous 32 byte memory block}
|
|
[if>=0 {In the first 32K...}
|
|
$60& if=0 {...wrap around visible screen memory}
|
|
tmp 160- ret]
|
|
tmp
|
|
ret
|
|
] PrevBlock=
|
|
|
|
{ Find line with line number equal to Value and go there }
|
|
[def
|
|
Begin [do i= {Loop over program from beginning}
|
|
End^ if<>0 {Until end of program}
|
|
i; Value^ [if=0 {Or if matching value found}
|
|
i 2+ Active= {Skip past line number}
|
|
TestBreak! {Test for break request}
|
|
Statements!] {And continue from there}
|
|
i NextBlock! loop] {Otherwise try next line}
|
|
Prompt! `Line #0 {Line error}
|
|
] {GotoValue=}
|
|
|
|
{-----------------------------------------------------------------------+
|
|
|} >\vLR++ ret { RAM page 9 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$09a0
|
|
GotoValue=
|
|
|
|
{ Destructively print Value as signed decimal number }
|
|
[def
|
|
push
|
|
|
|
[if<0 {If vAC is negative (vAC, NOT value!)}
|
|
0 Value- Value= {Negate value}
|
|
$2d PrintChar!] {Print minus sign}
|
|
|
|
0 k= {Suppress leading zeroes}
|
|
|
|
Value [if<0 {Bring large unsigned values in range}
|
|
-30000 Value+ Value= {Now Value<=35535, we need Value<=42767: OK}
|
|
3 k=]
|
|
|
|
10000 PrintDigit! {Print ten thousands, largest for 16 bits}
|
|
1000 PrintDigit! {Print thousands}
|
|
100 PrintDigit! {Print hundreds}
|
|
10 PrintDigit! {Print tens}
|
|
$30 Value+ PrintChar! {Print ones}
|
|
|
|
pop ret
|
|
] PrintValue=
|
|
|
|
[def
|
|
Prompt! `Stack #0 {Stack error}
|
|
] StackError=
|
|
|
|
[def
|
|
Prompt! `Syntax #0 {Syntax error}
|
|
] SyntaxError=
|
|
|
|
{-----------------------------------------------------------------------+
|
|
|} >\vLR++ ret { RAM page 10 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$0aa0
|
|
|
|
{ Parse an inline keyword. Returns 0 for failure }
|
|
[def
|
|
\vLR; tmp= {vLR points to inline argument}
|
|
Active j= {Save Active in case word match fails}
|
|
[do
|
|
tmp, <tmp++ {Next expected character from argument}
|
|
if<>0 {Compare until non-zero}
|
|
i=
|
|
Active, {Grab next character from line}
|
|
$20| {Ignore case}
|
|
i^ [if=0 <Active++ loop] {Accept if character matches}
|
|
j Active= {Restore program pointer on mismatch}
|
|
[do tmp, <tmp++ if<>0loop] {Eat remaining characters}
|
|
tmp!]
|
|
Spaces! {Remove trailing whitespace on match}
|
|
tmp! {Effectively returns past the keyword}
|
|
] Keyword=
|
|
|
|
{ Parse an unsigned decimal number and put in Value }
|
|
[def
|
|
$8000 {Stays negative if we don't see any digits}
|
|
[do
|
|
Value= {Update partial result}
|
|
2<< Value+ 1<< i= {Multiply by 10 before adding decimal}
|
|
|
|
Active, {Grab next character}
|
|
$30- {'0'} if>=0 {Bail out if out of range}
|
|
10- {'9'} if<0 {Decimal digit}
|
|
10+ {Map in 0..9 range}
|
|
i+ {Add it to value}
|
|
<Active++
|
|
loop]
|
|
Value {Result, negative value indicates error}
|
|
ret
|
|
] {Number=}
|
|
|
|
{-----------------------------------------------------------------------+
|
|
|} >\vLR++ ret { RAM page 11 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$0ba0
|
|
Number=
|
|
|
|
{ Verify that there is nothing else on the line, then continue with next }
|
|
[def
|
|
Active, [if<>0
|
|
$3a^ [if=0 {Accept statements separated by colon (':')}
|
|
<Active++ Statements!]
|
|
SyntaxError!] {There must be nothing left on the line}
|
|
Active NextBlock! Active= {Advance to next line}
|
|
End^ [if<>0 {Stop at end of program}
|
|
&_BasicProgram Active^ {Also stop if we came from the input buffer}
|
|
if<>0 Active 2+ Active= {Skip past line number}
|
|
Statements!] {And continue from there}
|
|
Prompt! #0 {Program finished ok}
|
|
] EndOfLine=
|
|
|
|
{ Clear variables but not arrays. Returns begin address for programs }
|
|
[def
|
|
0; i= {Top of memory}
|
|
2 {Clear variables and FOR state}
|
|
[do
|
|
j=
|
|
i 54- i= {i -= 2*27}
|
|
[do
|
|
0 i. {Clear byte}
|
|
<i++ {Advance pointer}
|
|
<i, if<>0loop] {Until end of page}
|
|
j 1- if<>0loop]
|
|
&_BasicProgram Begin=
|
|
ret
|
|
] {Clear=}
|
|
|
|
{-----------------------------------------------------------------------+
|
|
|} >\vLR++ ret { RAM page 12 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$0ca0
|
|
Clear=
|
|
|
|
{ Process a full expression, result in Value and vAC }
|
|
[def
|
|
push
|
|
|
|
\vSP, 141- {Check stack for at least 12 bytes above $81}
|
|
{Expression: 4, Term: 4, Factor: 4}
|
|
[if<0 StackError!] {Too complex expression AND too deep}
|
|
|
|
{First term}
|
|
Keyword! `- #0
|
|
[if<>0 {Accept unary minus}
|
|
Term!
|
|
0 Value- {Negate}
|
|
else
|
|
Keyword! `+ #0 {Ignore unary plus}
|
|
Term!]
|
|
|
|
push %0= {Put partial result on stack}
|
|
[do {Optional additional terms}
|
|
Keyword! `+ #0
|
|
[if<>0
|
|
Term!
|
|
%0 Value+ %0= {Perform addition}
|
|
loop]
|
|
Keyword! `- #0
|
|
[if<>0
|
|
Term!
|
|
%0 Value- %0= {Perform subtraction}
|
|
loop]
|
|
]
|
|
%0 Value= pop {Make stack value the result}
|
|
pop ret
|
|
] Expression=
|
|
|
|
[def
|
|
Prompt! `Value #0 {Value error}
|
|
] ValueError=
|
|
|
|
{-----------------------------------------------------------------------+
|
|
|} >\vLR++ ret { RAM page 13 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$0da0
|
|
|
|
{ Process an expression term, result in Value and vAC }
|
|
[def
|
|
push
|
|
Factor! {First factor}
|
|
push Value %0= {Put partial result on stack}
|
|
[do {Optional additional factors}
|
|
Keyword! `* #0
|
|
[if<>0
|
|
Factor!
|
|
%0 Multiply! %0=
|
|
loop]
|
|
Keyword! `/ #0
|
|
[if<>0
|
|
Factor!
|
|
%0 Divide! %0=
|
|
loop]
|
|
Keyword! `% #0
|
|
[if<>0
|
|
Factor!
|
|
%0 Divide! i %0=
|
|
loop]
|
|
]
|
|
%0 Value= pop {Make stack value the result}
|
|
pop ret
|
|
] Term=
|
|
|
|
>\vLR++ ret {Hop to next page}
|
|
|
|
_Statements5=* {Borrow a few bytes here for RUN}
|
|
|
|
Keyword! `run #0
|
|
[if<>0
|
|
Clear! {Clear variables}
|
|
deek Value= {First program line, if any}
|
|
GotoValue!] {Also tests for break}
|
|
|
|
&_Statements6 call
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 14 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$0ea0
|
|
|
|
{ Calculate vAC / Value, result in vAC, remainder in i }
|
|
[def
|
|
j= {i:j is the Remainder:Quotient pair}
|
|
Value^ k= {Park sign information}
|
|
j [if<0 0 j- j= ] {Non-negative}
|
|
Value [if<0 0 Value- Value=] {Non-negative}
|
|
[if=0 ValueError!] {Avoid division by zero}
|
|
|
|
0 i=
|
|
[do
|
|
tmp= {Loop counter}
|
|
i i+ i= {Shift left}
|
|
j [if<0 <i++] {Carry bit over to i}
|
|
j j+ j= {Shift left}
|
|
i Value- [if>=0 i= <j++] {Result bit}
|
|
tmp 1+ 15& {Iterate 16 times}
|
|
if<>0loop]
|
|
|
|
k [if<0 0 j- ret] {Return with corrected sign}
|
|
j ret
|
|
] {Divide=}
|
|
|
|
{-----------------------------------------------------------------------+
|
|
|} >\vLR++ ret { RAM page 15 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$0fa0
|
|
Divide=
|
|
|
|
{ Calculate vAC * Value, result in vAC }
|
|
[def
|
|
tmp=
|
|
0 j= {Result variable}
|
|
1 {First bit}
|
|
[do {Loop over all 16 bits}
|
|
i= tmp& {Test next bit left}
|
|
[if<>0 j Value+ j=] {Add partial term}
|
|
Value Value+ Value= {Shift left}
|
|
i i+ if<>0loop] {Until all done}
|
|
j
|
|
ret
|
|
] Multiply=
|
|
|
|
{ Get variable and calculate its address }
|
|
[def
|
|
0; i= {Top of memory as base for variables}
|
|
Active, {Next character from line}
|
|
$5f& {Ignore case}
|
|
$40- {'@'} [if>=0 {Bail out if out of range}
|
|
27- {'Z'} if<0 {Letter A..Z, @ or a..z}
|
|
<Active++ {Accept character}
|
|
1<< i+ {Address is base-52+2*n}
|
|
ret] {Return address on success}
|
|
SyntaxError!
|
|
] Variable=
|
|
|
|
{ Eat whitespace. Returns non-zero }
|
|
[def
|
|
[do Active, $20^ if=0 <Active++ loop]
|
|
ret
|
|
] Spaces=
|
|
|
|
{-----------------------------------------------------------------------+
|
|
|} >\vLR++ ret { RAM page 16 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$10a0
|
|
|
|
{ List program, count and print free bytes }
|
|
[def
|
|
push
|
|
|
|
Begin {List program from start of program memory}
|
|
[do {Loop over all program lines}
|
|
j=
|
|
End^ if<>0 {Repeat until the last line}
|
|
TestBreak! {Test for break request}
|
|
j; Value= PrintValue! {Print line number}
|
|
<j++ {Print line text}
|
|
[do {Loop over all characters in program line}
|
|
<j++ j,
|
|
if<>0 PrintChar!
|
|
loop]
|
|
Newline!
|
|
j NextBlock! {Advance to next block}
|
|
loop]
|
|
|
|
[do {Continue looping, now over free memory}
|
|
Value= {Subtotal}
|
|
0; {Retrieve top of memory from RAM[0:1]}
|
|
$80- $c0- {Correct for space used by variables}
|
|
j^ if<>0 {If not equal to j}
|
|
j NextBlock! j= {Advance to next block}
|
|
Value 32+ {Count another 32-byte block}
|
|
loop]
|
|
|
|
PrintChar PrintCharScreen^
|
|
[if=0 {When not in SAVE mode}
|
|
PrintValue! {vAC>=0 triggers conversion without sign}
|
|
PrintS! ``bytes`free #0
|
|
]
|
|
|
|
pop ret
|
|
] {List=}
|
|
|
|
{-----------------------------------------------------------------------+
|
|
|} >\vLR++ ret { RAM page 17 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$11a0
|
|
List=
|
|
|
|
{ Conditionally print leading decimal digit }
|
|
[def
|
|
push
|
|
i= {Radix as argument, keep in i}
|
|
Value [do {Calculate Value/Radix}
|
|
i- {Subtract i}
|
|
if>=0 {As many times as fits}
|
|
Value=
|
|
<k++ {Increment 0..9 times}
|
|
loop]
|
|
k [if<>0 {If non-zero digit or non-leading zero}
|
|
$30| PrintChar! {Map to $30..$39 range and print digit}
|
|
$30 k=] {And mark all further zeroes as non-leading}
|
|
pop ret
|
|
] PrintDigit=
|
|
|
|
{ Parse relational operator }
|
|
{ Use same encoding as original Tiny BASIC }
|
|
{ Doesn't accept >< (just use <>) }
|
|
[def
|
|
push
|
|
0 k=
|
|
|
|
Keyword! `< #0 {'<' in bit 0}
|
|
[if<>0 <k++]
|
|
|
|
Keyword! `> #0 {'>' in bit 2}
|
|
[if<>0 k 4+ k=]
|
|
|
|
Keyword! `= #0 {'=' in bit 1}
|
|
[if<>0 k 2+ k=]
|
|
|
|
k
|
|
pop ret
|
|
] RelOp=
|
|
|
|
&_Buffer deek End= {At startup 'End' comes from loaded segment}
|
|
2+ {Active=} {BASIC command(s) to run at startup}
|
|
|
|
{-----------------------------------------------------------------------+
|
|
|} >\vLR++ ret { RAM page 18 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$12a0
|
|
Active=
|
|
|
|
{ Error reporting function and re-entry point for main loop }
|
|
{ Call with inline partial error message, or with #0 for no error }
|
|
[def
|
|
\vLR; tmp= {vLR points to inline string argument}
|
|
[<Pos, 2- if>0 Newline!] {Conditional newline}
|
|
0 \vSP. {Reset stack}
|
|
tmp, [if<>0 {Test for error in first byte of message}
|
|
$3f {Begin error messages with '?'}
|
|
[do {Print inline string as prelude}
|
|
PrintChar!
|
|
tmp, <tmp++
|
|
if<>0loop]
|
|
PrintS! ``error #0
|
|
32- {$ffe0}
|
|
Active& {Align to begin of block}
|
|
{ 0+}{dummy offset} deek {Fetch active line number from offset 0}
|
|
[if<>0 {Input buffer has line number 0, don't print}
|
|
Value= {Prepare line number for printing}
|
|
PrintS! ``in` #0
|
|
PrintValue!] {Print line number}
|
|
Newline!]
|
|
|
|
PrintS! `Ok #0 {'Ok'}
|
|
Newline!
|
|
|
|
{ Main loop }
|
|
[do
|
|
0 {Interactive mode is 'line 0'}
|
|
GetLine! {Get line from console}
|
|
if=0loop {Do nothing for empty lines}
|
|
Insert! {Test for line number and insert or delete}
|
|
if>0loop] {If success, continue without prompt}
|
|
|
|
#\LDWI {1-byte hack to fall through and skip 'Prompt='}
|
|
] Prompt=
|
|
|
|
Statements! {Execute statements}
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 19 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$13a0
|
|
|
|
_Print=*
|
|
|
|
{PRINT}
|
|
|
|
Active, [if<>0 {Special case for newlines}
|
|
$3a^ if<>0 {Same for colon}
|
|
|
|
[do {PRINTLIST}
|
|
Active, if<>0 {Until end of line}
|
|
$3a^ if<>0 {or ':'}
|
|
$18^ {'"' = $22 = $3a^$18}
|
|
[if=0
|
|
[do {PRINTSTRING} {String constant}
|
|
<Active++ {Skip past opening quote or string character}
|
|
Keyword! #$22 #0 {'"'}
|
|
if=0
|
|
Active, {Next character}
|
|
if<>0 {Silently accept unterminated string}
|
|
PrintChar!
|
|
loop] {To PRINTSTRING}
|
|
else
|
|
Expression!
|
|
PrintValue!]
|
|
Keyword! #$2c #0 {','}
|
|
[if<>0
|
|
[do
|
|
$20 PrintChar!
|
|
<Pos, 2- {Correct for 2 pixel indentation}
|
|
7& if<>0loop] {Tab stops every 4 characters}
|
|
loop] {To PRINTLIST}
|
|
Keyword! #$3b #0 {';'}
|
|
if<>0loop {To PRINTLIST}
|
|
Newline!] {When no trailing ',' or ';'}
|
|
else
|
|
Newline!] {Special case for newlines and colon}
|
|
|
|
EndOfLine!
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 20 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$14a0
|
|
|
|
_Statements3=*
|
|
|
|
Keyword! `? #0
|
|
[if=0 Keyword! `print #0]
|
|
[if<>0 &_Print call] {PRINT}
|
|
|
|
Keyword! `input #0
|
|
[if<>0
|
|
[do
|
|
Active,
|
|
PrintChar! {Be nice and show variable name in prompt}
|
|
Variable! {Parse variable name}
|
|
Address= {Park here}
|
|
Spaces!
|
|
4-- Active %2= {Save program pointer on stack}
|
|
31| 31- deek %0= {Current line number in program}
|
|
[do
|
|
$3f PrintChar! {'?'}
|
|
Newline! {Avoid dealing with partially printed lines}
|
|
%0 {Line number for errors}
|
|
GetLine! {Let user type something}
|
|
if=0loop] {Repeat with prompt when nothing is typed}
|
|
Expression! {Accept arbitrary expression as input \o/}
|
|
Address: {Store received value in variable}
|
|
%2 Active= 4++ {Restore program pointer from stack}
|
|
Keyword! `, #0 {','}
|
|
if<>0loop] {Next variable}
|
|
EndOfLine!]
|
|
|
|
&_Statements4 call
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 21 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$15a0
|
|
|
|
_Statements4=*
|
|
|
|
Keyword! `cls #0
|
|
[if<>0
|
|
$100 peek >Pos. {Start at top of page}
|
|
14 [do {14 newlines}
|
|
j=
|
|
Newline!
|
|
j 1- if>0loop]
|
|
[do {Continue until video table is normal}
|
|
Newline!
|
|
$100 peek 8^ if<>0loop]
|
|
8 >Pos. {Return cursor to top of page}
|
|
EndOfLine!]
|
|
|
|
Keyword! `list #0
|
|
[if<>0 List! EndOfLine!]
|
|
|
|
Keyword! `save #0
|
|
[if<>0
|
|
\romType, \romTypeValue_ROMv3-
|
|
[if<0 ValueError!] {Error on ROM before v3}
|
|
&_Save call]
|
|
|
|
&_Statements5 call
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 22 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$16a0
|
|
|
|
_Statements6=*
|
|
|
|
Keyword! `new #0
|
|
[if<>0
|
|
Clear! {Clear variables}
|
|
End= {Clear program}
|
|
List! {To print number of free bytes}
|
|
Prompt! #0] {Return to prompt}
|
|
|
|
Keyword! `let #0 {LET is optional}
|
|
Variable!
|
|
Address= {Park here}
|
|
Spaces!
|
|
Keyword! #$28 #0 {'('}
|
|
[if<>0 {Optional array index}
|
|
Expression!
|
|
[if<0 ValueError!] {Index must be non-negative}
|
|
>Address, Value- 2- >Address.
|
|
End Address^ {64K safe bound check}
|
|
[if<0 End {Opposite signs}
|
|
else Address End-] {Equal signs}
|
|
[if<0 ValueError!]
|
|
Keyword! #$29 #0 {')'}
|
|
if=0 SyntaxError!]
|
|
Keyword! `= #0 {'='}
|
|
[if=0 SyntaxError!]
|
|
Expression! {Evaluate expression}
|
|
Address: {Store value in variable}
|
|
EndOfLine!
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 23 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$17a0
|
|
|
|
_Save=*
|
|
|
|
{SAVE}
|
|
|
|
{ Saving works by redirecting PrintChar and then calling List.
|
|
The first line out will be an implicit bare newline. This signals
|
|
to BabelFish that a new program starts and the old can be deleted. }
|
|
|
|
0;
|
|
\sysArgs3. {Number of bits to send (zero)}
|
|
96- Address= {SAVE line buffer}
|
|
|
|
[def
|
|
push
|
|
k=
|
|
\sysArgs3, 8+ \sysArgs3. {Always count 8 more bits}
|
|
<Pos, 6- {At or near left margin}
|
|
[if<0 {A newline has started}
|
|
10 Address. {Terminate the save line}
|
|
Address 31| 31^ Address= {Back to start of buffer}
|
|
\sysArgs0: {Prepare SYS call}
|
|
1 \sysArgs2. {First bit}
|
|
\SYS_SendSerial1_v3_80
|
|
_sysFn= 80!! {SYS call to send bits to serial port}
|
|
[if<>0 {'BreakError' would be better}
|
|
3 \serialRaw. {Not a great hack...}
|
|
TestBreak!] {...to initiate a break error}
|
|
8 \sysArgs3.]
|
|
k Address. <Address++ {Put in buffer}
|
|
PrintCharScreen! {Print to screen as well}
|
|
pop ret
|
|
] PrintChar= {Globally redefines original PrintChar}
|
|
|
|
[do
|
|
\serialRaw, 255^ {Wait for BabelFish to appear idle}
|
|
if<>0loop]
|
|
|
|
List! {List whole program, redirected}
|
|
32 PrintChar! {Flushes the last line}
|
|
|
|
PrintCharScreen PrintChar= {Restore PrintChar}
|
|
EndOfLine!
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 24 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$18a0
|
|
|
|
_Newline=*
|
|
|
|
{Newline}
|
|
|
|
{ Prepare for printing on new line }
|
|
\SYS_VDrawBits_134 _sysFn= {Prepare SYS call}
|
|
|
|
0 <Pos. {Go back to start of line}
|
|
\sysArgs2. {All-zero output pattern}
|
|
|
|
>Pos, 15+ {Go down upto 8 upto 15 lines}
|
|
120& [if=0 8] {Wrap around and re-align to 8-fold if needed}
|
|
>Pos.
|
|
|
|
\sysArgs6; \sysArgs0: {Apply caller-defined colors}
|
|
|
|
Pos \sysArgs4: {sysArgs[4:5] is position on screen}
|
|
[do
|
|
134!! <\sysArgs4++ {SYS call and advance to next slice}
|
|
134!! <\sysArgs4++ {A bit unrolling for speed}
|
|
\sysArgs4, 160^ {Test for end of screen}
|
|
if<>0loop]
|
|
|
|
\videoTable i= {videoTable}
|
|
255| deek {Gets [$100] aka Y[0] in vAC high byte}
|
|
Pos- \vACH, {Compare with Y position}
|
|
[if=0
|
|
do
|
|
i 16+ _sysArgs0= {sysArgs0 looks 8 entries ahead of i}
|
|
peek \sysArgs2. {Swap scanlines}
|
|
i, _sysArgs0.
|
|
\sysArgs2, i.
|
|
<i++ <i++ {Advance to next entry in video table}
|
|
<i, 224^ if<>0loop] {Until all done}
|
|
|
|
<Pos++ <Pos++ {Indent by 2 pixels}
|
|
ret
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 25 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$19a0
|
|
|
|
_Line=*
|
|
|
|
{LINE}
|
|
|
|
1 \sysArgs0: $100 \sysArgs2: {Vector pair U, V}
|
|
|
|
Expression! push %0= {Park dX argument on stack}
|
|
Keyword! `, #0 {','}
|
|
[if=0 SyntaxError!]
|
|
Expression! j= {dY argument as j}
|
|
|
|
[if<0 {Make dY >= 0}
|
|
0 #\SUBW #\sysArgs2 {Inline assembly}
|
|
\sysArgs2: {V = -V}
|
|
0 j- j=]
|
|
|
|
%0 i= {dX argument as i}
|
|
[if<0 {Make dX >= 0}
|
|
0 #\SUBW #\sysArgs0 {Inline assembly}
|
|
\sysArgs0: {U = -U}
|
|
0 i- i=]
|
|
|
|
j- [if<0 {Make dX >= dY}
|
|
i tmp= j i= tmp j= {Swap i, j}
|
|
\sysArgs0; tmp= \sysArgs2; {Swap U, V}
|
|
\sysArgs0: tmp \sysArgs2:]
|
|
|
|
pop {Shorter than 2++}
|
|
|
|
&_Line2 call
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| RAM page 26 |
|
|
+-----------------------------------------------------------------------}
|
|
*=$1aa0
|
|
|
|
_Line2=*
|
|
|
|
{Continuation of LINE}
|
|
|
|
Value {dY argument}
|
|
[if<0 $7800 else $8800] {Vertical gap}
|
|
\sysArgs4:
|
|
|
|
i tmp= {Setup line drawing inner loop}
|
|
k= {Bresenham's error}
|
|
|
|
[do {Inner loop}
|
|
\sysArgs7, Pos. {Plot pixel in pen color}
|
|
|
|
tmp 1- tmp= if>=0 {Loop counter}
|
|
|
|
k j- j- k= {Update Bresenham's error}
|
|
[if<0 {If threshold exceeded}
|
|
i+ i+ k=
|
|
\sysArgs2; Pos+ Pos=] {Pos += V {Step along short side}}
|
|
\sysArgs0; Pos+ Pos= {Pos += U {Step along long side}}
|
|
|
|
<Pos, 160- [if>=0 {Wrapping around left/right border}
|
|
[if>0 >Pos++ 64+] <Pos.] {Map X back into 0..159 range}
|
|
|
|
>Pos, $78& [if=0 {This occurs midscreen if text has scrolled}
|
|
\sysArgs4; Pos+ Pos=] {Map Y back into 8..127 range}
|
|
|
|
loop]
|
|
|
|
EndOfLine! { :-) }
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| BASIC data |
|
|
+-----------------------------------------------------------------------}
|
|
|
|
{ BASIC data begins here. In this setup the interpreter can be patched
|
|
to include a BASIC program and a first command for execution }
|
|
|
|
*=$1ba0 _Buffer=* {Must be the "line" before user program}
|
|
##_Buffer {Initial end pointer, points to startup command}
|
|
`NEW #0 {'NEW' to start interactive session}
|
|
|
|
*=$1bc0 _BasicProgram=* {BASIC program starts here}
|
|
|
|
{-----------------------------------------------------------------------+
|
|
| |
|
|
+-----------------------------------------------------------------------}
|
|
|