Poraka BASIC is a small integer-only BASIC interpreter for the
ilo virtual computer.

Enter numbered program lines to build or edit a program. Use:

- `RUN` to execute the current program
- `NEW` to erase all stored lines
- `BYE` to exit

Supported statements:

- `PRINT "TEXT"`
- `PRINT <expr>`
- `LET A = <expr>`
- `INPUT A`
- `GOTO <line>`
- `IF <expr> = <expr> GOTO <line>`
- `IF <expr> < <expr> GOTO <line>`
- `IF <expr> > <expr> GOTO <line>`
- `REM ...`
- `END`

Variables are `A` through `Z`. Expressions are integer only and
are evaluated left-to-right using `+`, `-`, `*`, and `/`.

~~~
: start
i lica....
r init
: repl
i lica....
r load_program
i liju....
r repl

: init
i lica....
r clear_program
i liju....
r clear_variables

: clear_variables
i lili....
r Variables
r ClearPtr
i stlili..
d 26
r ClearCount
i st......
: clear_variables_loop
i life....
r ClearCount
i ligtli..
d 0
r clear_variables_body
i cj......
i re......
: clear_variables_body
i li......
d 0
i life....
r ClearPtr
i st......
i life....
r ClearPtr
i liadli..
d 1
r ClearPtr
i stlife..
r ClearCount
i lisuli..
d 1
r ClearCount
i stliju..
r clear_variables_loop

: clear_program
i lili....
r ProgramBuffer
r ProgramWrite
i stlili..
d 0
r LineCount
i stlili..
d 0
r CurrentIndex
i stlili..
d 0
r EOFFlag
i st......
i re......

: halt
i liio....
d 6

: load_program
: lp_loop
i lica....
r read_line
i life....
r EOFFlag
i lieqli..
d -1
r halt
i cj......
i lili....
r InputBuffer
r SrcPtr
i stlica..
r skip_spaces
i lifefeli
r SrcPtr
r TempChar
i st......
i life....
r TempChar
i lieqli..
d 0
r lp_loop
i cj......
i lica....
r is_bye_command
i life....
r ByeFlag
i lieqli..
d -1
r halt
i cj......
i lica....
r is_new_command
i life....
r NewFlag
i lieqli..
d -1
r lp_new
i cj......
i lica....
r is_run_command
i life....
r RunFlag
i lieqli..
d -1
r lp_run
i cj......
i life....
r TempChar
i liltli..
d 48
r lp_loop
i cj......
i life....
r TempChar
i ligtli..
d 57
r lp_loop
i cj......
i lica....
r store_line
i liju....
r lp_loop
: lp_new
i lica....
r clear_program
i liju....
r lp_loop
: lp_run
i lica....
r clear_variables
i lica....
r execute_program
i re......

: is_run_command
i lili....
d 0
r RunFlag
i st......
i life....
r SrcPtr
i fe......
i lieqli..
d 82
r ir_match
i cj......
i re......
: ir_match
i lili....
d -1
r RunFlag
i stre....

: is_new_command
i lili....
d 0
r NewFlag
i st......
i life....
r SrcPtr
i fe......
i lieqli..
d 78
r in_match
i cj......
i re......
: in_match
i lili....
d -1
r NewFlag
i stre....

: is_bye_command
i lili....
d 0
r ByeFlag
i st......
i life....
r SrcPtr
i fe......
i lieqli..
d 66
r ib_match
i cj......
i re......
: ib_match
i lili....
d -1
r ByeFlag
i stre....

: read_line
i lili....
r InputBuffer
r InputPtr
i stlili..
d 0
r ReadLen
i stlili..
d 0
r EOFFlag
i st......
: rl_loop
i liio....
d 1
i duli....
d -1
i eqli....
r rl_eof
i cj......
i duli....
d 10
i eqli....
r rl_finish
i cj......
i duli....
d 13
i eqli....
r rl_finish
i cj......
i life....
r InputPtr
i st......
i life....
r InputPtr
i liadli..
d 1
r InputPtr
i stlife..
r ReadLen
i liadli..
d 1
r ReadLen
i stliju..
r rl_loop
: rl_eof
i life....
r ReadLen
i lieqli..
d 0
r rl_set_eof
i cj......
i liju....
r rl_finish
: rl_set_eof
i lili....
d -1
r EOFFlag
i st......
: rl_finish
i drli....
d 0
i life....
r InputPtr
i stre....
i re......

: store_line
i lili....
r InputBuffer
r SrcPtr
i stlica..
r parse_number
i lifeli..
r ParseResult
r TargetLine
i stlica..
r find_line
i life....
r FoundFlag
i lieqli..
d 0
r sl_new
i cj......
i life....
r ProgramWrite
i life....
r FoundIndex
i liad....
r LineAddrs
i st......
i liju....
r sl_copy_setup
: sl_new
i life....
r TargetLine
i life....
r LineCount
i liad....
r LineNumbers
i st......
i life....
r ProgramWrite
i life....
r LineCount
i liad....
r LineAddrs
i st......
: sl_copy_setup
i life....
r ProgramWrite
i li......
r DstPtr
i st......
i lili....
r InputBuffer
r SrcPtr
i st......
: sl_copy
i lifefeli
r SrcPtr
r TempChar
i stlife..
r TempChar
i life....
r DstPtr
i st......
i life....
r SrcPtr
i liadli..
d 1
r SrcPtr
i stlife..
r DstPtr
i liadli..
d 1
r DstPtr
i stlife..
r TempChar
i lieqli..
d 0
r sl_done
i cj......
i liju....
r sl_copy
: sl_done
i lifeli..
r DstPtr
r ProgramWrite
i stlife..
i life....
r FoundFlag
i lieqli..
d 0
r sl_bump_count
i cj......
i re......
: sl_bump_count
i life....
r LineCount
i liadli..
d 1
r LineCount
i stre....

: execute_program
i lili....
d 0
r CurrentIndex
i st......
: ep_loop
i life....
r CurrentIndex
i life....
r LineCount
i ltli....
r ep_body
i cj......
i re......
: ep_body
i life....
r CurrentIndex
i liad....
r LineAddrs
i feli....
r SrcPtr
i stlica..
r parse_number
i lica....
r skip_spaces
i lifefeli
r SrcPtr
r TempChar
i st......
i life....
r TempChar
i lieqli..
d 80
r stmt_print
i cj......
i life....
r TempChar
i lieqli..
d 76
r stmt_let
i cj......
i life....
r TempChar
i lieqli..
d 73
r stmt_i
i cj......
i life....
r TempChar
i lieqli..
d 71
r stmt_goto
i cj......
i life....
r TempChar
i lieqli..
d 82
r stmt_rem
i cj......
i life....
r TempChar
i lieqli..
d 69
r stmt_end
i cj......
i lica....
r next_line
i liju....
r ep_loop

: stmt_i
i life....
r SrcPtr
i liad....
d 1
i fe......
i lieqli..
d 78
r stmt_input
i cj......
i liju....
r stmt_if

: stmt_print
i life....
r SrcPtr
i liadli..
d 5
r SrcPtr
i stlica..
r skip_spaces
i lifefeli
r SrcPtr
r TempChar
i st......
i life....
r TempChar
i lieqli..
d 34
r print_string_stmt
i cj......
i lica....
r parse_expression
i lifeli..
r ExprResult
r NumberTemp
i stlica..
r print_number
i lica....
r print_line_end
i lica....
r next_line
i liju....
r ep_loop

: print_string_stmt
i life....
r SrcPtr
i liadli..
d 1
r SrcPtr
i st......
: pss_loop
i lifefeli
r SrcPtr
r TempChar
i st......
i life....
r TempChar
i lieqli..
d 34
r pss_done
i cj......
i life....
r TempChar
i lieqli..
d 0
r pss_done
i cj......
i life....
r TempChar
i liio....
d 0
i life....
r SrcPtr
i liadli..
d 1
r SrcPtr
i stliju..
r pss_loop
: pss_done
i life....
r SrcPtr
i liadli..
d 1
r SrcPtr
i stlica..
r print_line_end
i lica....
r next_line
i liju....
r ep_loop

: stmt_let
i life....
r SrcPtr
i liadli..
d 3
r SrcPtr
i stlica..
r skip_spaces
i lifefeli
r SrcPtr
r TempChar
i stlife..
r TempChar
i lisuli..
d 65
r TargetVar
i stlife..
r SrcPtr
i liadli..
d 1
r SrcPtr
i stlica..
r skip_spaces
i lifefeli
r SrcPtr
r TempChar
i st......
i life....
r TempChar
i lieqli..
d 61
r let_have_eq
i cj......
i liju....
r let_have_eq
: let_have_eq
i life....
r SrcPtr
i liadli..
d 1
r SrcPtr
i stlica..
r parse_expression
i life....
r ExprResult
i life....
r TargetVar
i liad....
r Variables
i stlica..
r next_line
i liju....
r ep_loop

: stmt_input
i life....
r SrcPtr
i liadli..
d 5
r SrcPtr
i stlica..
r skip_spaces
i lifefeli
r SrcPtr
r TempChar
i stlife..
r TempChar
i lisuli..
d 65
r TargetVar
i stlili..
d 63
d 0
i io......
i liio....
d 32
i lica....
r read_line
i lili....
r InputBuffer
r SrcPtr
i stlica..
r parse_number
i life....
r ParseResult
i life....
r TargetVar
i liad....
r Variables
i stlica..
r next_line
i liju....
r ep_loop

: stmt_goto
i life....
r SrcPtr
i liadli..
d 4
r SrcPtr
i stlica..
r parse_number
i lifeli..
r ParseResult
r TargetLine
i stlica..
r find_line
i life....
r FoundFlag
i lieqli..
d 0
r halt
i cj......
i lifeli..
r FoundIndex
r CurrentIndex
i stliju..
r ep_loop

: stmt_if
i life....
r SrcPtr
i liadli..
d 2
r SrcPtr
i stlica..
r parse_expression
i lifeli..
r ExprResult
r LeftValue
i stlica..
r skip_spaces
i lifefeli
r SrcPtr
r CompChar
i stlife..
r SrcPtr
i liadli..
d 1
r SrcPtr
i stlica..
r parse_expression
i lifeli..
r ExprResult
r RightValue
i stlica..
r skip_spaces
i life....
r SrcPtr
i liadli..
d 4
r SrcPtr
i stlica..
r parse_number
i lifeli..
r ParseResult
r TargetLine
i st......
i life....
r CompChar
i lieqli..
d 61
r if_eq
i cj......
i life....
r CompChar
i lieqli..
d 60
r if_lt
i cj......
i liju....
r if_gt
: if_eq
i life....
r LeftValue
i life....
r RightValue
i eq......
i liju....
r if_after_compare
: if_lt
i life....
r LeftValue
i life....
r RightValue
i lt......
i liju....
r if_after_compare
: if_gt
i life....
r LeftValue
i life....
r RightValue
i gt......
: if_after_compare
i lieqli..
d 0
r if_false
i cj......
i lica....
r find_line
i life....
r FoundFlag
i lieqli..
d 0
r halt
i cj......
i lifeli..
r FoundIndex
r CurrentIndex
i stliju..
r ep_loop
: if_false
i lica....
r next_line
i liju....
r ep_loop

: stmt_rem
i lica....
r next_line
i liju....
r ep_loop

: stmt_end
i life....
r LineCount
r CurrentIndex
i stliju..
r ep_loop

: next_line
i life....
r CurrentIndex
i liadli..
d 1
r CurrentIndex
i stre....

: skip_spaces
: ss_loop
i lifefeli
r SrcPtr
r TempChar
i st......
i life....
r TempChar
i lieqli..
d 32
r ss_advance
i cj......
i re......
: ss_advance
i life....
r SrcPtr
i liadli..
d 1
r SrcPtr
i stliju..
r ss_loop

: parse_number
i lica....
r skip_spaces
i lili....
d 1
r NumSign
i stlili..
d 0
r ParseResult
i stlifeli
r SrcPtr
r TempChar
i st......
i life....
r TempChar
i lieqli..
d 45
r pn_neg
i cj......
i liju....
r pn_digits
: pn_neg
i lili....
d -1
r NumSign
i stlife..
r SrcPtr
i liadli..
d 1
r SrcPtr
i st......
: pn_digits
i lifefeli
r SrcPtr
r TempChar
i st......
i life....
r TempChar
i liltli..
d 48
r pn_done
i cj......
i life....
r TempChar
i ligtli..
d 57
r pn_done
i cj......
i life....
r ParseResult
i limuli..
d 10
r ParseResult
i stlife..
r TempChar
i lisuli..
d 48
r Temp
i stlife..
r ParseResult
i life....
r Temp
i adli....
r ParseResult
i stlife..
r SrcPtr
i liadli..
d 1
r SrcPtr
i stliju..
r pn_digits
: pn_done
i life....
r NumSign
i lieqli..
d -1
r pn_apply_sign
i cj......
i re......
: pn_apply_sign
i lili....
d 0
r ParseResult
i fesuli..
r ParseResult
i st......
i re......

: parse_value
i lica....
r skip_spaces
i lifefeli
r SrcPtr
r TempChar
i st......
i life....
r TempChar
i liltli..
d 65
r pv_number
i cj......
i life....
r TempChar
i ligtli..
d 90
r pv_number
i cj......
i life....
r TempChar
i lisuli..
d 65
r Temp
i stlife..
r Temp
i liad....
r Variables
i feli....
r ParseResult
i stlife..
r SrcPtr
i liadli..
d 1
r SrcPtr
i st......
i re......
: pv_number
i liju....
r parse_number

: parse_expression
i lica....
r parse_value
i lifeli..
r ParseResult
r ExprResult
i st......
: pe_loop
i lica....
r skip_spaces
i lifefeli
r SrcPtr
r OpChar
i st......
i life....
r OpChar
i lieqli..
d 43
r pe_plus
i cj......
i life....
r OpChar
i lieqli..
d 45
r pe_minus
i cj......
i life....
r OpChar
i lieqli..
d 42
r pe_mul
i cj......
i life....
r OpChar
i lieqli..
d 47
r pe_div
i cj......
i re......
: pe_plus
i life....
r SrcPtr
i liadli..
d 1
r SrcPtr
i stlica..
r parse_value
i life....
r ExprResult
i life....
r ParseResult
i adli....
r ExprResult
i stliju..
r pe_loop
: pe_minus
i life....
r SrcPtr
i liadli..
d 1
r SrcPtr
i stlica..
r parse_value
i life....
r ExprResult
i life....
r ParseResult
i suli....
r ExprResult
i stliju..
r pe_loop
: pe_mul
i life....
r SrcPtr
i liadli..
d 1
r SrcPtr
i stlica..
r parse_value
i life....
r ExprResult
i life....
r ParseResult
i muli....
r ExprResult
i stliju..
r pe_loop
: pe_div
i life....
r SrcPtr
i liadli..
d 1
r SrcPtr
i stlica..
r parse_value
i life....
r ExprResult
i life....
r ParseResult
i di......
i swdrli..
r ExprResult
i stliju..
r pe_loop

: find_line
i lili....
d 0
r SearchIndex
i stlili..
d 0
r FoundFlag
i st......
: fl_loop
i life....
r SearchIndex
i life....
r LineCount
i ltli....
r fl_body
i cj......
i re......
: fl_body
i life....
r SearchIndex
i liad....
r LineNumbers
i fe......
i life....
r TargetLine
i eqli....
r fl_found
i cj......
i life....
r SearchIndex
i liadli..
d 1
r SearchIndex
i stliju..
r fl_loop
: fl_found
i lili....
d -1
r FoundFlag
i stlifeli
r SearchIndex
r FoundIndex
i st......
i re......

: print_number
i life....
r NumberTemp
i lieqli..
d 0
r pn_zero
i cj......
i life....
r NumberTemp
i liltli..
d 0
r pn_neg_out
i cj......
i liju....
r pn_prepare
: pn_neg_out
i liio....
d 45
i lili....
d 0
r NumberTemp
i fesuli..
r NumberTemp
i st......
: pn_prepare
i lili....
d 0
r DigitCount
i st......
: pn_split
i life....
r NumberTemp
i lidi....
d 10
i swli....
r Remainder
i stli....
r NumberTemp
i stlife..
r Remainder
i life....
r DigitCount
i liad....
r Digits
i stlife..
r DigitCount
i liadli..
d 1
r DigitCount
i stlife..
r NumberTemp
i ligtli..
d 0
r pn_split
i cj......
: pn_emit_loop
i life....
r DigitCount
i lieqli..
d 0
r pn_done_emit
i cj......
i life....
r DigitCount
i lisuli..
d 1
r DigitCount
i stlife..
r DigitCount
i liad....
r Digits
i fe......
i liadli..
d 48
d 0
i io......
i liju....
r pn_emit_loop
: pn_zero
i lili....
d 48
d 0
i io......
i re......
: pn_done_emit
i re......

: newline
i lili....
d 10
d 0
i io......
i re......

: print_line_end
i lica....
r skip_spaces
i lifefeli
r SrcPtr
r TempChar
i st......
i life....
r TempChar
i lieqli..
d 59
r ple_no_newline
i cj......
i lica....
r newline
i re......
: ple_no_newline
i re......

o 56000
: Variables
* 26
: LineNumbers
* 256
: LineAddrs
* 256
: Digits
* 16
: ProgramBuffer
* 4096
: InputBuffer
* 256

: ProgramWrite
d 0
: LineCount
d 0
: CurrentIndex
d 0
: SrcPtr
d 0
: DstPtr
d 0
: InputPtr
d 0
: ReadLen
d 0
: EOFFlag
d 0
: ParseResult
d 0
: ExprResult
d 0
: TargetLine
d 0
: FoundIndex
d 0
: FoundFlag
d 0
: SearchIndex
d 0
: NumSign
d 0
: Temp
d 0
: TempChar
d 0
: OpChar
d 0
: TargetVar
d 0
: LeftValue
d 0
: RightValue
d 0
: CompChar
d 0
: NumberTemp
d 0
: DigitCount
d 0
: Remainder
d 0
: RunFlag
d 0
: NewFlag
d 0
: ByeFlag
d 0
: ClearPtr
d 0
: ClearCount
d 0
~~~