Class: IntegerBASIC

Inherits:
NativeFileType show all
Defined in:
lib/native_file_types/apple2/IntegerBASIC.rb

Direct Known Subclasses

ScAsm

Instance Attribute Summary

Attributes inherited from NativeFileType

#aux_code, #contents, #file_system_image, #file_type, #filename, #meta_data

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from NativeFileType

#<=>, #==, all_native_file_types, best_fit, code_for_tests, compatability_score, #data_without_header, file_type_matches?, #full_filename, #header_length, #initialize, is_valid_file_if, #load_address, load_address, matching_score, native_file_types_possible_on_file_system, non_matching_score, #to_hex_dump, #to_info_dump, #type_description

Methods included from SubclassTracking

extended

Constructor Details

This class inherits a constructor from NativeFileType

Class Method Details

.file_system_file_types ⇒ Object 



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# File 'lib/native_file_types/apple2/IntegerBASIC.rb', line 4

def IntegerBASIC.file_system_file_types
  {
    AppleDos=>0x01
  }
end

Instance Method Details

#to_listing ⇒ Object

Integer Basic file format: <Length_of_file> (16-bit little endian) <Line> .….. <Line>

where <Line> is: 1 byte: Line length 2 bytes: Line number, binary little endian <token> <token> <token> .….. <end-of-line token>

<token> is one of: $12 - $7F: Tokens as listed below: 1 byte/token $80 - $FF: ASCII characters with high bit set $B0 - $B9: Integer constant, 3 bytes: $B0-$B9,

followed by the integer value in
2-byte binary little-endian format
(Note: a $B0-$B9 byte preceded by an
 alphanumeric ASCII(hi_bit_set) byte
 is not the start of an integer
 constant, but instead part of a
 variable name)

<end-of-line token> is: $01: One byte having the value $01

(Note: a $01 byte may also appear
 inside an integer constant)

Note that the tokens $02 to $11 represent commands which can be executed as direct commands only – any attempt to enter then into an Integer Basic program will be rejected as a syntax error. Therefore, no Integer Basic program which was entered through the Integer Basic interpreter will contain any of the tokens $02 to $11. The token $00 appears to be unused and won’t appear in Integer Basic programs either. However, $00 is used as an end-of-line marker in S-C Assembler source files, which also are of DOS file type “I”.

(note here a difference from Applesoft Basic, where there are no “direct mode only” commands - any Applesoft commands can be entered into an Applesoft program as well).



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# File 'lib/native_file_types/apple2/IntegerBASIC.rb', line 58

def to_listing
  length=contents[0]+contents[1]*256
  index=2
  s=""

  while (index<length)
    in_REM = false
    in_QUOTE = false
    lead_SP = false
    last_AN = false
    last_TOK = false

    line_length=contents[index]
    index+=1 #skip over the "line length" field
    line_no=contents[index]+contents[index+1]*256
    index+=2 #skip over the "line number" field
    s+=sprintf("%u ",line_no)
    done_line=false
    while (!done_line)			
      lead_SP = lead_SP || last_AN
      b=contents[index]
      if (b >= 0x80 ) then
        if ( !in_REM && !in_QUOTE && !last_AN && (b>= 0xB0 && b <= 0xB9) ) then
          integer = contents[index+1]+contents[index+2]*256
          index+=2
          s+=sprintf( (last_TOK && lead_SP ) ? " %d" : "%d", integer )
          lead_SP = true
        else
      
          c = b & 0x7F
          if (!in_REM && !in_QUOTE && last_TOK && lead_SP && is_alnum(c)) then
            s+=" "
          end
          if ( c >= 0x20 ) then
            s+=c.chr						
          else
            s+="^"+(c+0x40).chr
          end
          last_AN = is_alnum(c)
        end
        last_TOK =false			
      else
        
        token = INTEGER_BASIC_TOKENS[b]
        lastchar = token[token.length-1]
        case b
          when IB_REM_TOKEN then in_REM = true
          when IB_QUOTE_START then in_QUOTE = true
          when IB_QUOTE_END then in_QUOTE = false
        end
        
        if lead_SP && ( is_alnum(token[0]) ||
              b == IB_UNARY_PLUS ||
              b == IB_UNARY_MINUS ||
              b == IB_QUOTE_START  ) then
          s+=" "
        end
        s+=token
        last_AN  = false
        lead_SP = is_alnum(lastchar) || lastchar == ')' || lastchar == '\"'
        last_TOK = true
      end
      index+=1
      done_line=(index>length)||(contents[index]==0x01)
    end
    s+="\n"
    index+=1        # skip over "end of line" marker
  end
       s
  
end